KeywordsLipoma, hemangioma, schwannoma, chordoma, skeleton
Tumors of the soft somatic tissues form a very small component in the spectrum of tumors requiring surgical treatment in the head and neck region. These tumors may arise from the musculofascial compartment or the visceral compartment in the head and neck region. The histologic variants of benign and malignant soft tissue tumors are listed in Table 15.1 . The latest classification of soft-tissue tumors from the WHO in 2013 has resulted in a change of nomenclature of a number of tumors, and these changes are important for the oncologist to be aware of to avoid confusion in management.
|TISSUE OF ORIGIN||BENIGN||INTERMEDIATE*||MALIGNANT|
|Fat||Lipoma||Atypical lipomatous tumor||Liposarcoma|
|Fibrous tissue/myofibroblastic||Fibroma||Desmoid type fibromatosis |
Dermatofibrosarcoma, solitary fibrous tumor
|Fibrosarcoma, myxofibrosarcoma, low-grade fibromyxoid sarcoma, malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma|
|Blood vessels||Hemangioma||Kaposiform hemangioendothelioma||Angiosarcoma, epithelioid hemangioendothelioma|
|Skeletal muscle||Rhabdomyoma||Embryonal rhabdomyosarcoma, alveolar rhabdomyosarcoma, pleomorphic rhabdomyosarcoma|
|Nerve sheath tumors||Schwannoma, neurofibroma, granular cell tumor||MPNST, epithelioid MPNST, malignant granular cell tumor|
|Tumors of uncertain differentiation||Fibromyxoma, myxoma||Atypical fibroxanthoma, myoepithelioma, phosphaturic mesenchymal tumor||Synovial sarcoma, epithelioid sarcoma, alveolar soft part sarcoma, extraskeletal Ewing sarcoma, undifferentiated/unclassified sarcomas|
The most frequently encountered benign tumors in the head and neck region are lipomas, hemangiomas, lymphangiomas, and neurofibromas. Hemangiomas and lymphangiomas are quite common in children. Only 4.3% of soft-tissue sarcomas in adults arise in the head and neck region ( Fig. 15.1 ). The site distribution of adult soft-tissue sarcomas in the head and neck region is shown in Fig. 15.2 . Soft-tissue sarcomas can arise from almost any part of the anatomy in the head and neck area, although the parotid glands, neck, face, forehead, and scalp are the sites encountered most frequently. The most common mode of presentation is a mass lesion or symptoms resulting from pressure on contiguous neurovascular structures or the viscera. The diagnosis of a soft-tissue tumor is made easily by clinical examination, although for surgical treatment planning, additional workup is essential. This workup usually consists of radiographic evaluation and establishment of accurate tissue diagnosis. The histologic distribution of soft-tissue sarcomas in the head and neck region in adults is shown in Fig. 15.3 .
Most patients present with the complaint of a mass lesion, with or without any local pressure symptoms. Masses on the face, neck, or scalp show a visual deformity, and those in the oral cavity, pharynx, or larynx may have symptoms of obstruction to the upper aerodigestive tract. Clinical evaluation requires a detailed physical examination of the presenting mass lesion. The location, dimensions, consistency, and fixation to deeper structures are important parameters to arrive at a clinical diagnosis. Lipomas generally present with a mass that is soft in consistency and is mobile over the deeper soft tissues ( Fig. 15.4 ). On the other hand, hemangiomas and lymphangiomas are also soft in consistency and may give the impression of a compressible or even cystic lesion. Deep-seated and intramuscular hemangiomas present with a diffuse ill-defined soft mass and need radiographic assessment to define the dimensions and location of the tumor. In contrast, tumors of fibrous tissue or neural origin present as firm to hard solid lesions. The degree of mobility or fixation to surrounding or deep structures raise the index of suspicion for malignancy. Bimanual palpation often will give enough information about the nature of the lesion ( Fig. 15.5 ). Lesions of vascular origin involving the skin such as an angiosarcoma may have a characteristic appearance with discoloration like ecchymosis, and nodular lesions of vascular origin involving this skin have discoloration ranging from cherry red to purple. Clinical evaluation should particularly assess fixation to overlying skin or underlying soft tissues, muscle, or bone. For lesions of the pharynx and larynx, adequate endoscopic evaluation is necessary to define the exact location and extent of the tumor.
Accurate assessment of the anatomic extent of a soft-tissue tumor of the head and neck region requires that it be evaluated in all three dimensions. Computed tomography (CT) and magnetic resonance imaging (MRI) scans are most valuable in demonstrating the anatomic extent of the lesion and its relationship to vital structures. For tumors that are highly vascular or are of neurovascular origin, magnetic resonance (MR) angiography or a direct arteriography may be indicated. If direct angiography demonstrates large feeding vessels and a highly vascular lesion, then serious consideration should be given to preoperative embolization of the tumor to minimize blood loss during surgery.
As an example, a CT scan of a patient with a large lipoma in the posterior compartment of the neck is shown in Fig. 15.6 . Note the presence of a uniform, well-delineated, hypodense mass displacing the anatomic structures in the left side of the neck medially and occupying the entire posterior compartment of the left side of the neck. Lesions that are in proximity to or involving the underlying bone require bone windows on a CT scan to accurately assess the extent of bone invasion. In contrast to CT scans, an MRI scan has the capability of providing images in the axial, coronal, and sagittal planes to more accurately define the anatomic extent of the lesion. MRI scans in a postcontrast T1-weighted images in a patient with a hemangioma of the tongue in axial, coronal, and sagittal planes clearly demonstrate the anatomic extent of this lesion ( Figs. 15.7 through 15.9 ). An accurate assessment of the size and extent of the lesion within the tongue musculature is demonstrated.
In addition to obtaining CT and MRI with contrast, the ability to obtain three-dimensional reconstructions of the CT images allows accurate three-dimensional assessment of the location and extent of the tumor for appropriate surgical planning for complete resection and reconstruction. The patient shown in Fig. 15.10 has a solitary fibrous tumor of the masticator space. His CT and MRI scans in axial, coronal, and sagittal planes are shown in Figs. 15.11 through 15.13 . Three-dimensional reconstruction of his CT scan and CT angiogram vividly shows the anatomic location and extent of the tumor with displacement and involvement of the mandible, orbital floor, and skull base, as well as the blood supply to the tumor ( Fig. 15.14 ).
It is vitally important that accurate tissue diagnosis be established before definitive surgical intervention, particularly in patients whose soft-tissue tumors are suspected to be malignant upon clinical examination. Biopsy techniques are shown in Fig. 15.15 . Although fine-needle aspiration cytology may be informative in some patients, for accurate morphologic classification of the soft-tissue tumor, a core of tissue is essential. This sample may be obtained by a Tru-Cut core biopsy or an open incisional biopsy. For small, well-circumscribed lesions, an excisional biopsy may be performed to provide an adequate tissue sample for accurate histologic interpretation. If an incisional biopsy is to be performed, the incision should be placed in such a fashion that at the time of the definitive surgical excision, the incisional biopsy site can be encompassed in the surgical specimen. Inappropriate placement of the biopsy incision often can jeopardize definitive surgical treatment and the potential for a curative resection.
The TNM staging system for soft tissue sarcomas, include anatomic as well as histologic features of the tumor. Thus for T staging, tumor size and local invasion, as well as nodal and distant metastases are included. In addition to the TNM criteria, histologic grade of the primary tumor is added to assign a stage to the sarcoma ( Table 15.2 ). In order to assign stage groupings, the American Joint Committee on Cancer (AJCC) is currently gathering data based on this new classification.
|T1 Tumor ≤2 cm|
|T2 Tumor >2 cm and <4 cm|
|T3 Tumor >4 cm|
|T4 Tumor with invasion of adjacent structures|
|T4a Invasion of orbit, skull base, dura, central compartment viscera, facial skeleton, or pterygoid muscles|
|T4b Invasion of brain, prevertebral muscles, carotid artery encasement, or perineural spread to central nervous system|
|N0 No nodal metastases|
|N1 Nodal metastases|
|M0 No distant metastases|
|M1 Any distant metastases|
|G1 Total differentiation, mitotic count, and necrosis score of 2 or 3|
|G2 Total differentiation, mitotic count, and necrosis score of 4 or 5|
|G3 Total differentiation, mitotic count, and necrosis score of 6, 7, or 8|
Factors Affecting Choice of Treatment
Surgical excision is the mainstay of treatment for all soft-tissue tumors. Benign neoplasms are adequately excised, preferably in a monobloc fashion, by an appropriate surgical approach depending on the size and anatomic location of the tumor. Highly vascular lesions are best managed with preoperative embolization when feasible to minimize blood loss. For malignant soft-tissue tumors, on the other hand, various factors that influence eventual prognosis must be considered. These factors are related to the histologic type and grade of the tumor as well as the size and location of the sarcoma. Clearly en bloc three-dimensional resection of the tumor with adequate soft-tissue margins is the hallmark of surgical treatment of soft-tissue sarcomas in any part of the body. However, because of the proximity of vital organs and structures in the head and neck region, the broad principles of soft-tissue sarcoma surgery elsewhere in the body cannot be adhered to rigidly in the head and neck region. Often surgical excision must be tailored to avoid unnecessary sacrifice or injury to uninvolved contiguous vital structures to secure adequate margins. In general, small, low-grade lesions carry an excellent prognosis. On the other hand, patients with large, high-grade lesions have a high incidence of local recurrence and distant metastases and have a poor prognosis. Regional lymph nodes usually are not treated electively.
Role of Radiotherapy
The need for adjunctive radiation therapy should be considered in patients with tumors of high-grade histology and for whom the margins are unsatisfactory or close. External radiotherapy or brachytherapy may be used with equal efficacy. The choice of treatment modality depends on the site, histology, and size of the field to be treated. Although enhanced local control is achieved with adjunctive radiation therapy, improvement in survival is not noted.
In most patients who require surgery for soft-tissue tumors, no specific preoperative preparation is required. However, when a massive resection is to be undertaken and significant blood loss is anticipated, sufficient quantities of blood should be available in reserve to replace operative blood loss. As mentioned earlier, highly vascular lesions are best managed with preoperative embolization when appropriate. If resection of the carotid artery is anticipated, then preoperative testing with balloon occlusion is required to assess the adequacy of cerebral blood flow from the opposite side. An arterial bypass graft may be necessary in certain circumstances. Appropriate reconstructive surgery should be planned preoperatively based on the size, extent, and location of the surgical defect anticipated from resection of the tumor, and reconstruction may involve microvascular free tissue transfer. When tumors approach or involve the skull base, neurosurgical assistance is required and should be planned preoperatively. Similarly, sarcomas extending into the mediastinum or the chest may need assistance from thoracic surgeons to carry out a safe and complete resection. When sarcoma resection requires that the visceral compartment be entered, preoperative antibiotics should be administered to reduce the risk of postoperative sepsis.
Tumors of Adipose Tissue
Lipoma of the Neck
Lipomas in the head and neck region may present as simple subcutaneous lesions or as complex deep-seated tumors. Several examples are presented here to demonstrate the spectrum of head and neck lipomas. The patient whose CT scans with contrast are shown in Fig. 15.16 has a large lipoma involving the lateral compartment and retroesophageal/prevertebral region. She presented with a long-standing history of an ill-defined fullness in the anterior compartment of the neck on the left-hand side and a retropharyngeal bulge in the oropharynx. The axial views of the CT scans at the level of the oropharynx and lower cervical region show a homogeneous well-defined nonenhancing mass in the prevertebral space, similar to subcutaneous fat consistent with a radiologic diagnosis of lipoma (see Fig. 15.16 ). Axial views of the T1-weighted MRI scans at the same levels as the CT show a similar well-defined mass of fatty consistency ( Fig. 15.17 ). Surgical excision of this lesion requires a simple transverse incision along a midneck skin crease of sufficient length to gain adequate exposure. The skin incision is deepened through the platysma, and the fascia overlying the sternocleidomastoid muscle is incised to gain exposure of the tumor. By alternate blunt and sharp dissection, the sternocleidomastoid muscle is freed from the underlying tumor and retracted laterally to show the carotid sheath ( Fig. 15.18 ). A well-encapsulated yellowish smooth tumor is seen clearly. By alternate blunt and sharp dissection, the tumor is mobilized carefully, paying attention to the superior laryngeal nerve at the upper end and recurrent laryngeal nerve at the lower end. The superior thyroid artery had to be divided to get the necessary dissection. The superior laryngeal nerve had to be retracted cephalad. In some situations even the inferior thyroid artery may need to be divided. The tumor could be mobilized thereafter, keeping it intact ( Fig. 15.19 ). The feeding blood vessels to the tumor are relatively small vessels that are clamped, divided, and ligated. The specimen is delivered in a monobloc fashion ( Fig. 15.20 ). Drainage of the surgical field usually is not necessary. The skin incision is closed in layers.
Lipomas may arise in any part of the head and neck region and occasionally may present adjacent to or within the substance of a major salivary gland. The patient shown in Fig. 15.21 presented with a mass in the tail of the parotid gland that was soft to palpation. The differential diagnosis in this clinical setting is a parotid tumor, a lipoma, or a vascular lesion in the parotid gland. Imaging studies suggested this to be a lipoma. Surgical exposure of a lesion in the parotid gland requires a standard parotidectomy incision with elevation of the skin flap deep to the platysma. The skin flap is elevated while remaining close to the platysma muscle to avoid injury to peripheral branches of the facial nerve as they exit from the parotid gland. The lesion in this patient is readily visible in Fig. 15.22 after elevation of the skin flap. By alternate blunt and sharp dissection, the lesion is excised, remaining close to the capsule of the tumor to avoid injury to the intraparotid branches of the facial nerve. The skin incision is closed in layers with placement of a small Penrose drain that usually can be removed within 24 hours.
On rare occasions, lipomas may occur in the deep parapharyngeal space and the prevertebral space. The patient whose oropharynx is shown in Fig. 15.23 had increasing difficulty with swallowing and a sense of a narrowed swallowing passage. Examination of the oropharynx through the open mouth showed a significant bulge of the posterior and posterolateral pharyngeal wall on the left-hand side that caused compromise of the airway and the swallowing passage. Upon palpation this lesion felt soft and extended from the nasopharynx behind the soft palate cephalad to the lateral wall of the pyriform sinus caudad. The lesion extended well beyond the midline in the prevertebral space, pushing the posterior pharyngeal wall and the tonsil anteriorly. An axial view of the CT scan with contrast through the upper part of the neck vividly demonstrates a multilobulated lipoma in the prevertebral space extending into the parapharyngeal space behind the carotid sheath on the left-hand side ( Fig. 15.24 ). An MRI scan in the coronal plane demonstrates the cephalocaudad extent of this tumor with displacement of the posterolateral pharyngeal wall ( Fig. 15.25 ).
The surgical approach for excision of this lesion required a midcervical incision with careful dissection deep to the sternomastoid muscle and medial to the carotid sheath, with mobilization and delivery of the multilobulated lipoma from the parapharyngeal space laterally and the prevertebral space medially. The superior thyroid artery was divided and ligated. The superior laryngeal nerve was retracted cephalad to gain exposure. The laryngopharyngeal complex was retracted medially and the carotid sheath was retracted laterally to gain exposure and excise the tumor in a monobloc fashion without rupturing its capsule. The surgical specimen shown in Fig. 15.26 demonstrates complete excision of this massive lipoma of the prevertebral/parapharyngeal space.
Madelung disease is a clinical condition in which diffuse infiltration of fat occurs in all compartments of the neck, including the supraclavicular fossae and the submandibular and periparotid regions. This condition is often seen in men of Mediterranean origin. The patient shown in Fig. 15.27 presented with progressive swelling on both sides of his face and neck from Madelung disease. Surgical excision of this abnormal fatty infiltrate is indicated only for cosmetic reasons. The operative procedure is very tedious and time-consuming. The surgical procedure is akin to a modified neck dissection with preservation of all the vital structures including the sternocleidomastoid muscle, the internal jugular vein, the accessory nerve, the submandibular salivary gland, and the peripheral cutaneous branches of the cervical plexus to minimize anesthesia of the skin of the neck. Because of diffuse infiltration of the fat into the anatomic spaces and fascial compartments, dissection is not easy, and tissue planes generally do not separate readily. It is advisable to perform the surgical procedure on both sides of the neck in stages to avoid excessive blood loss and to reduce the length of the operative procedure. The postoperative appearance of the patient 1 year following bilateral neck surgery is shown in Fig. 15.28 .
Low-Grade Liposarcoma (or Atypical Lipomatous Tumor) of the Hypopharynx
Liposarcomas may arise in the fascial or visceral compartments of the head and neck region and present as a soft-tissue tumor. The extent of surgical resection clearly depends on the anatomic location, size, and histologic grade of the primary lesion. The patient shown here presented with slight discomfort in the throat of several months’ duration. Flexible fiberoptic nasolaryngoscopy examination of the hypopharynx and larynx showed a smooth submucosal mass involving the medial wall of the left pyriform sinus, as shown in Fig. 15.29 . No mucosal ulceration was present, and the lesion did not extend up to the apex of the pyriform sinus. A barium swallow examination shown in Fig. 15.30 clearly demonstrates a smooth-lined mass in the postcricoid region causing partial obstruction of the cervical esophagus. Endoscopy under general anesthesia showed that the lesion was pedunculated and freely mobile over the underlying musculature of the larynx and postcricoid region.
Most malignant lesions in this location would require an open pharyngotomy and adequate resection. However, this patient’s tumor was small, well demarcated, and pedunculated, and therefore an endoscopic excision could be performed in a monobloc fashion. The patient is placed under general endotracheal anesthesia, and a wide Jako laryngoscope is introduced and the larynx is suspended. Alternatively a bivalve laryngoscopy can be used for wide exposure of the hypopharynx. After adequate exposure of the lesion is obtained, the operating microscope is brought into the field to provide proper visualization of the lesion to facilitate the operative procedure. With use of endoscopic microlaryngeal instruments, the lesion is excised with an intact capsule from its pedunculated base. Alternatively, the lesion can be excised through its pedicle with a CO 2 laser, remaining clear of the tumor. The surgical specimen shows a lesion that grossly appears to be like a well-encapsulated lipoma and is adequately excised in toto ( Fig. 15.31 ). Histologic analysis of this specimen, however, showed that this lesion was a low-grade liposarcoma. Because of the malignant nature of this lesion and a relatively limited excision, this patient received postoperative external radiation therapy to enhance local control at the surgical resection site.
In contrast to well-differentiated liposarcomas, high-grade liposarcomas are infiltrative lesions with ill-defined and often diffuse margins. In this category of high-grade lipomatous tumors are dedifferentiated liposarcoma, myxoid liposarcoma, and pleomorphic liposarcoma. Up to 10% of well-differentiated liposarcomas may progress to high-grade, dedifferentiated liposarcomas. Surgical resection for high-grade liposarcomas therefore entails a radical monobloc resection, working through normal tissue planes, around the clinically palpable, grossly demonstrable, and radiologically identified extent of the tumor. Such a radical resection entails traversing through various tissue planes and sacrificing soft tissues, muscles, and other neurovascular structures as deemed necessary. If adequate clearance of the tumor with negative margins is not achieved, then consideration should be given to interstitial implantation of residual tumor with after-loading catheters. The radiation source used in that clinical setting may be 192 Ir or 125 I. On the other hand, if gross total clearance of the tumor is achieved and concern exists about the margins or the possibility of microscopic extensions of tumor, then external irradiation as adjunctive treatment will provide disease control comparable with that achieved by interstitial radiotherapy. In general, high-grade sarcomas and other sarcomas exceeding 5 cm in diameter are candidates for consideration of adjunctive postoperative radiotherapy. Local control of disease is enhanced with adjunctive irradiation, although long-term survival is not affected.
Tumors of Fibrous Tissue
Fibromas and Benign Fibrous Tissue Tumors
Benign fibrous tumors of the head and neck region are relatively uncommon. However, tumors of fibroblastic origin may present either as a benign fibroma, a calcified fibroma, or a simple benign fibrous tumor. A somewhat more aggressive benign fibromatous tumor is the solitary fibrous tumor, which has a higher potential for local invasiveness and a higher risk of local recurrence. Surgical treatment of these lesions requires a complete excision in an extracapsular fashion with negative margins, without sacrificing any vital structures. The patient shown in Fig. 15.32 presented with a firm mass adjacent to the lamina of the thyroid cartilage in the right side of the neck that had been present for several years. He reported local discomfort in that area and a history of increasing size of the mass. A CT scan without contrast, shown in Fig. 15.33 , demonstrates a calcified tumor in the central compartment of the neck located posterior to the upper pole of the thyroid lobe. Surgical excision of this tumor required a midcervical incision with adequate mobilization of the adjacent tissues and excision of the tumor in a monobloc fashion.
Dermatofibrosarcoma protuberans (DFSP) is a low-grade malignant tumor of fibrous tissue origin most commonly seen in the head and neck area. However, it also can present in the region of the shoulder or trunk or, rarely, on the extremities. The tumor arises from the dermal layer of the skin and often presents as a multinodular lesion ( Fig. 15.34 ). The patient described here presented with a history of having felt several dermal nodules on her forehead for the past 3 years. Most patients do not show local invasion of deeper tissues at initial presentation. Therefore excision of a generous portion of the involved skin and the underlying soft tissues is deemed adequate as definitive treatment.
The extent of surgical resection for this patient is shown in Fig. 15.35 . Note the multiple, palpable nodules of this tumor located several centimeters apart, which required a wide excision of the skin of the forehead and underlying soft tissues up to the pericranium. The tumor nodules were mobile over the underlying pericranium without involvement of the bone, and therefore full-thickness excision of the skin, subcutaneous tissue, the underlying occipitofrontalis muscle, and the pericranium was believed to be satisfactory. The surgical defect resulted in a bare surface of the frontal bone, which required vascularized soft tissue and skin for reconstruction. Repair of the surgical defect in this patient was accomplished with use of a radial forearm free flap. The postoperative appearance of the patient 2 years following surgery shows a satisfactory aesthetic and functional result ( Fig. 15.36 ).
Excision of Dermatofibrosarcoma Protuberans of Scalp and Reconstruction With a Latissimus Dorsi Muscle Free Flap and Skin Graft
The patient presented here has a large, nodular, protuberant, neglected dermatofibrosarcoma protuberans of the scalp on the forehead at the hairline ( Fig. 15.37 ). This lesion had been present for more than 7 years. The lesion was mobile over the underlying pericranium and did not involve the calvarium. Imaging studies failed to show any bone erosion. Surgical resection of this tumor required a wide three-dimensional excision including the underlying pericranium as the deep margin. A generous portion of the scalp is resected, exposing the underlying frontal and parietal bones. Reconstruction of such a surgical defect requires free tissue transfer. In this patient, a latissimus dorsi muscle flap was used to provide coverage over the bare bone and to provide soft tissue support for a split-thickness skin graft. The recipient vessels were anastomosed to the superficial temporal artery and vein on the left-hand side. The appearance of the patient approximately 6 weeks after surgery is shown in Fig. 15.38A . Note that the skin graft has taken 100% over the underlying muscle. With passage of time, the grafted area assumes the color and texture of the adjacent scalp and gives an excellent aesthetic outcome ( Fig. 15.38B ). It is crucial to emphasize that a wide, three-dimensional resection is required as initial surgical treatment for long-term control of this tumor.
Fibroosseous Lesion of the Neck (Gardner’s Syndrome)
Benign fibroosseous lesions are quite common in patients with Gardner’s syndrome. These lesions are often multiple and on occasion can get massive with local invasion. In spite of extensive local growth and invasion, they are histologically benign and do not have the potential to metastasize. The patient shown in Fig. 15.39 is a 12-year-old boy who has Gardner’s syndrome with multiple colonic polyposis, for which he underwent colectomy. In addition he has multiple fibromatous lesions in various parts of his body that are asymptomatic. However, the tumor in the upper part of the neck on right-hand side has shown significant growth over the past 4 years, causing grotesque facial deformity. Imaging studies showed this to be an extensive soft-tissue tumor, with pressure effect on the body of the mandible, causing developmental growth deformity ( Fig. 15.40 ).
Surgical excision was warranted to address the facial deformity and permit normal growth of the body of the mandible in this child. Excision of a generous portion of the skin over the tumor is planned for a satisfactory skin closure to achieve facial symmetry ( Fig. 15.41 ). Although these tumors appear to be relatively avascular on imaging studies, they do have profuse microcirculation causing bleeding from small vessels during surgery. The crucial point in this particular patient is identification and preservation of peripheral branches of the lower division of the facial nerve. Once the facial nerve is identified, dissection proceeds along soft-tissue planes around the tumor ( Fig. 15.42 ). A monobloc resection of the tumor is achieved. The large dead space from surgery requires a suction drain. The wound is closed in the usual fashion. The postoperative appearance of the patient 6 months following surgery shows excellent restoration of the facial contour and symmetry ( Fig. 15.43 ).
Solitary Fibrous Tumor (Hemangiopericytoma) of the Occipital Region
A solitary fibrous tumor (formerly known as hemangiopericytoma) is a low grade malignant tumor of fibroblastic origin. Although it is known to be locally aggressive, metastases are infrequent. The term solitary fibrous tumor is employed for these lesions when they occur in the pleural cavity, and the term hemangiopericytoma is often used for lesions involving the meninges, to reflect its aggressive behavior. There is, however, a significant debate among pathologists regarding the exact nomenclature for these locally aggressive tumors. The patient shown in Fig. 15.44 presented with a mass on the left-hand side of her neck in the suboccipital region. An open incisional biopsy was performed elsewhere to establish a histologic diagnosis. Upon clinical examination, the mass, which measured 5 cm, was smooth and fleshy and immobile over the deeper structures. A vascular bruit could be heard on auscultation over the surface of the tumor.
A contrast-enhanced CT scan of the upper part of the neck shows an enhancing lesion in the paraspinal region at the level of the second cervical vertebra ( Fig. 15.45 ). This well-circumscribed lesion is situated over the transverse processes and posterior arch of the upper cervical vertebrae. An arch aortogram showed that the major blood supply of this tumor is derived from the left vertebral artery. A selective left vertebral angiogram in a lateral projection shows a highly vascular lesion in the suboccipital region ( Fig. 15.46 ). The tortuous part of the vertebral artery near the transverse process of the second cervical vertebra is partly surrounded by this highly vascular tumor.
An anteroposterior projection of the left vertebral angiogram confirms the close relationship of the vertebral artery to this very vascular lesion ( Fig. 15.47 ). Preoperative embolization of the lesion was not possible, because the feeding vessels were very small although abundant, and selective catheterization through the vertebral artery was not feasible. No intraspinal or intracranial extension of the tumor could be demonstrated with radiographic studies.
Surgical excision of this highly vascular lesion situated in a difficult location requires a well-planned operation. Ample supplies of blood should be available before surgery. Because of the proximity of the tumor to the upper cervical vertebra, bone instruments should be available. Fogarty balloon catheters also should be available in the event of uncontrolled hemorrhage from the vertebral artery.
The patient is placed in the prone position under general endotracheal anesthesia. The head is fixed in flexion with neurosurgical tongs ( Fig. 15.48 ). An inverted U-shaped incision is made beginning in the midline at the spinous process of the seventh cervical vertebra. It extends cephalad up to the upper part of the occipital region and then curves back downward and laterally to encompass the scar of the previous biopsy and further down along the lateral aspect of the neck parallel to the trapezius muscle. The skin incision is deepened through the underlying soft tissues, and the inferiorly based skin flap is elevated as shown in Fig. 15.49 . Brisk hemorrhage from the scalp in the occipital region should be expected but is easily controlled with electrocautery. The skin flap is elevated down to the midcervical region to facilitate adequate exposure of the cervical vertebrae.
Mobilization of the tumor begins in the occipital region with detachment of the attachments of the suboccipital muscles from the lower border of the occipital bone, as shown in Fig. 15.50 . This maneuver will permit exposure of the suboccipital region, leaving the soft tissues attached to the pseudocapsule of the tumor. An incision is now made in the soft tissue overlying the spinous processes in the midline, and dissection proceeds laterally, leaving the paraspinous muscles attached to the tumor.
The paraspinous muscles of the left side are divided inferior to the lower border of the tumor. Further dissection on the undersurface of the tumor will permit its rotation anterolaterally to expose the posterior laminae of the cervical vertebrae and the posterior aspect of the transverse processes. This dissection should be done meticulously, gently, and with extreme caution to avoid inadvertent injury to the tortuous part of the vertebral artery ( Fig. 15.51 ). Branches from the vertebral artery providing blood supply to the tumor are carefully isolated, individually divided, and ligated.
With meticulous and slow dissection, the vertebral artery, which is in close proximity to the tumor, is separated as shown with a pointer in Fig. 15.52 . The tumor by now is totally mobilized and is ready to be delivered. Minor bleeding during mobilization of the tumor is to be expected. However, major blood loss may occur if rough handling in the region of the extracranial vertebral artery is undertaken. The surgical defect after removal of the tumor shows the bare occipital bone, the transected stumps of the paraspinous muscles, the transverse processes, and the spinous processes of the midcervical vertebrae along with the tortuous portion of the vertebral artery, which remains intact ( Fig. 15.53 ). Absolute hemostasis must be secured before closure of the incision begins.
A Penrose drain is inserted after irrigation of the wound, which is closed in two layers ( Fig. 15.54 ). Pressure dressings are applied because of the large raw area and the potential for oozing from the cut muscles. Immobilization of the cervical spine is unnecessary, because the vertebral column is intact. Although the suboccipital group of muscles and a portion of the paraspinous muscles in the upper part of the neck are resected, the stability of the cervical spine remains intact.
The specimen shows the excised scar of a previous biopsy with an en bloc excision of the tumor and its surrounding soft tissues ( Fig. 15.55 ). The cut surface of the specimen ( Fig. 15.56 ) shows a fleshy, homogeneous, well-circumscribed tumor, which on histologic examination confirmed the diagnosis of solitary fibrous tumor. The postoperative appearance of the patient is shown in Fig. 15.57 . Although a significant soft-tissue deficit is present at the site of the resection of the tumor in the posterior triangle of the neck, the stability of the cervical spine remains intact and the movements of the head and neck are unaffected.
Undifferentiated Pleomorphic Sarcoma (Malignant Fibrous Histiocytoma)
Undifferentiated pleomorphic sarcoma (UPS; previously referred to as malignant fibrous histiocytoma [MFH] ) may arise in any part of the head and neck region. The characteristics of this tumor are manifested by local invasion of adjacent soft tissues and bone, depending on the site of origin. This aggressive malignant tumor of the soft tissues requires a radical surgical resection with generous peripheral and deep margins in all three dimensions.
Undifferentiated Pleomorphic Sarcoma of the Nasolabial Region
The patient shown in Fig. 15.58 has a soft-tissue tumor adherent to the underlying nasal process of the maxilla along the right nasolabial region. An MRI scan in axial and coronal planes shows a well-demarcated tumor eroding the nasal process of the maxilla and the very lower end of the junction between the alar cartilage and the lower end of the nasal bone on the right-hand side. The mass was not readily visible on nasal endoscopy but could be palpated easily in the region of the right nasolabial fold. A needle biopsy of the mass revealed that it was a high-grade malignant tumor of fibrous origin. A lateral rhinotomy incision is marked around the nasal subunits of the ala and dorsum of the nose as landmarks ( Fig. 15.59 ). The MRI scan shown in Fig. 15.60 demonstrates a well-circumscribed mass on the anterolateral wall of the right nasal cavity involving the subcutaneous soft tissues and extending up to the submucosal plane.
The skin incision is made with a scalpel, and the remainder of the operative procedure is continued with an electrocautery. The skin flaps are elevated in the subcutaneous plane, keeping a generous margin of soft tissues around the palpable tumor. The upper flap is elevated up to the anterior wall of the maxilla laterally, the lower end of the nasal bone cephalad, the premaxillary region inferiorly, and the mucosa of the nasal cavity medially. The mass is thus completely exposed, and a monobloc excision of the mass, including the cartilaginous lateral wall of the nasal cavity, is performed ( Fig. 15.61 ). The surgical field following excision shows a through-and-through defect in the lateral wall of the nasal cavity ( Fig. 15.62 ). Hemostasis is secured with electrocautery. Because of the small size of the surgical defect, no specific reconstructive effort is necessary. The surgical specimen is removed in a monobloc fashion with sufficient soft-tissue margins ( Fig. 15.63 ). Nasal packing is introduced, and the surgical incision is closed in two layers ( Fig. 15.64 ). Final histopathologic examination confirmed the diagnosis of a benign fibrous histiocytoma. The patient’s appearance 7 weeks after surgery shows an excellent aesthetic outcome with a barely visible surgical scar ( Fig. 15.65 ). With the passage of time, this incision will merge with the skin lines and should be imperceptible.
Undifferentiated Pleomorphic Sarcoma of the Zygomatic Region
The patient shown in Fig. 15.66 previously had undergone local excision of this lesion, followed by radiation therapy. Prompt recurrence of the tumor required a radical surgical resection of the tumor with immediate reconstruction. The surgical resection required excision of the skin, adjacent soft tissues (including the lower eyelid), and the anterior surface of the zygomatic process. Reconstruction of the defect was accomplished with use of a Mustardé flap and a composite mucoperichondrial graft from the nasal septum. A postoperative photograph of the patient 1 year following surgery, shown in Fig. 15.67 , depicts an acceptable result.