Definition

(ICD-O code 8890/0)

Leiomyomas are benign, smooth muscle tumors which show varying degrees of differentiation.

Etiology

There is little in the way of smooth muscle within the sinonasal tract and the most likely source of smooth muscle is the vasculature of the region, although it is possible that the tumors may arise from pluripotential mesenchymal cells. There have been reports linking radiotherapy and cyclophosphamide treatment with the onset of leiomyosarcoma1,2 but there is no satisfactory evidence for factors predisposing to leiomyoma. Likewise, there is little evidence to suggest that benign leiomyomas predispose to leiomyosarcoma, although the literature (as is so common with rare benign tumors) contains conflicting evidence on this possibility.

Fu and Perzin described an area with the pattern of leiomyoma existing in a single case of leiomyosarcoma.3 Huang and Antonescu reported a clinicopathological and immunohistochemical analysis of 12 cases of sinonasal smooth muscle tumors, looking in particular at the histological parameters of circumscription, mucosal ulceration, cellularity, nuclear atypia, mitotic count, necrosis, and destruction of adjacent bony structures.4 They ultimately grouped them into 7 leiomyomas, 2 smooth muscle tumors with uncertain malignant potential, and 3 low-grade leiomyosarcomas. While this makes for interesting academic discussion with regard to the histopathology, the important clinical point was that all 12 patients were treated by surgical excision and only one patient with definitive leiomyosarcoma received postoperative irradiation. In all 12 cases, there was no evidence of local recurrence or metastases after a follow-up period that averaged over 7 years.

Synonyms

Angiomyoma, angioleiomyoma, vascular leiomyoma, nonvascular leiomyoma, epithelioid leiomyoma, leiomyoblastoma.

Incidence

While the head and neck is not an uncommon site for superficial smooth muscle tumors, primary leiomyomas of the sinonasal tract are very rare.4,5 Leiomyosarcomas appear to be slightly more common than benign leiomyomas in the literature and overall there is a female predilection of cases with a ratio of ~3:1. Leiomyomas are common in the uterus and the alimentary tract, in contrast to their rarity in the nose and sinuses. Enzinger and Weiss reported 7,748 leiomyomas, with 95% of them occurring in the female genital system, 3% in the skin, and 1.5% in the gastrointestinal tract.6 We have treated 3 patients in our cohort of >1,700 sinonasal tumors, all female.

Site

In the nose and sinuses, the tumor has been most commonly reported as arising from the turbinates with an additional smaller number of cases throughout the nasal cavity and sinuses.4,5,7–10 The alveolus and palate may be involved with spread into the nasal cavity and sinuses, and this simple fact accounts for some confusion in the literature as to the exact number of cases of this rare tumor, depending on whether the whole of the upper jaw is included in the overall count. In all of our 3 patients, the lesions arose on the lateral wall, either middle (2 cases) or inferior turbinate (1 case).

Diagnostic Features

Natural History

While leiomyomas can achieve a large size and extend throughout the maxilla, ethmoid, and sphenoid areas, they can be completely cured by total excision. The excision must be complete because recurrence is well documented, but is most likely to be residual disease as a consequence of inadequate resection.

Treatment

With the average size of these lesions being around 2 cm and their commonest site being the turbinate, they are ideally removed by modern endoscopic sinus surgery, as was the case in our patient. In the past and in countries where this is not available, lateral rhinotomy or midfacial degloving usually provide excellent access to allow complete removal of the tumor. This latter point cannot be overemphasized as these tumors may recur many years later and require more extensive procedures such as craniofacial resection. In younger patients and those in whom there is concern about adequacy of complete removal, long-term follow-up is advised with careful examination at approximately yearly intervals and appropriate imaging if symptoms and signs suggest residual disease.

Our youngest patient dramatically demonstrates the problems of undertreatment, having had a polypectomy at 5 years of age, followed by three lateral rhinotomies elsewhere and ultimately requiring a craniofacial resection at the age of 15 years in 1989 to remove the lesion from the skull base and nasal bones. She subsequently has had to have a reconstructive rhinoplasty, but happily has not had any further “recurrence” to date.

Definition

(ICD-O code 8890/3)

Leiomyosarcoma is a rare, malignant, mesenchymal tumor of smooth muscle phenotype that most frequently occurs in the uterine myometrium, the gastrointestinal (GI) tract, the retroperitoneum, and the skin. It is a rare tumor in the head and neck.

Etiology

Leiomyosarcoma, in common with other rare sarcomas, has been reported to occur following previous radiotherapy and, in a small number of cases, following treatment with cyclophosphamide. A total of 10 cases had been reported in the literature by 1990.1 Patients presented in these series had received radiation with or without systemic chemotherapy between 6 and 40 years previously. Unfortunately, as we have consistently pointed out in the sections on soft tissue tumors, the unreliability of these reports prior to the modern developments in immunohistochemistry and genetics makes it doubtful whether these lesions were always leiomyosarcomas. These radiation induced-tumors had been reported after orbital radiation for retinoblastoma, mediastinal and neck irradiation for ganglioneuroblastoma, and pelvic irradiation and treatment for Wilms tumor. The case of Lalwani and Kaplan was said to have occurred after radiation and cyclophosphamide treatment for Wegener′s granulomatosis, but it is quite likely that their case actually represented a T cell lymphoma and this raises the question whether or not the subsequent disease was indeed a leiomyosarcoma.1 The WHO classification 2005 now places radiation-induced sarcomas in a separate group.

Smooth muscle tumors are extraordinarily rare in the head and neck, probably because of the paucity of smooth muscle tissue; the most likely source is thought to be the arterial tunica media but it is also possible that they arise from pluripotential mesenchymal cells in common with other forms of sarcomas. Primary head and neck cutaneous leiomyosarcomas are thought to arise either from the muscular walls of blood vessels or from the erector pili muscles.

Incidence and Site

Leiomyosarcomas of the head and neck are essentially adult tumors with a peak incidence in the 5th decade of life and have an approximately equal sex distribution.2,3 Kuruvilla et al2 found only 9 examples of leiomyosarcoma out of 602 sinonasal tract sarcomas (1.5%) extracted from the files of the Armed Forces Institute of Pathology.

Leiomyosarcoma of the oral cavity has a particular predilection for the mandible and maxilla; ~70% of reported cases arise in the jaws with the remainder originating in the tongue, hard and soft palate, floor of mouth, buccal mucosa, gingiva, and upper lip. Those arising in the hard and soft palate and maxilla may further involve the paranasal sinuses and nasal cavity and this simple fact again complicates the figures for incidence in the sinonasal tract within the literature.4,5 Cutaneous leiomyosarcoma is not uncommon in the head and neck, usually presenting in older, male patients and varies in appearance between small plaques or nodules to extensive, ulcerating masses that may involve the nose and underlying paranasal sinuses.6

We have treated five patients with leiomyosarcoma. In the two earlier cases, there was extensive involvement of the maxillary sinuses and orbit. In the three more recent cases the disease involved the ethmoid and nasal cavity.

Diagnostic Features

Histological Features and Differential Diagnosis

The rapidly increasing literature on the complexity of diagnosis surrounding leiomyosarcomas, as with many other rare sarcomas, is an excellent demonstration of an increasing understanding of the subject, but although recent cytogenetic studies of leiomyosarcomas in particular have shown highly complex genetic aberrations, as yet no specific abnormalities within leiomyosarcomas have been identified.8,9 Depending on their grade, leiomyosarcomas are more or less infiltrative, with bone and cartilage invasion being more frequent than surface or seromucinous gland invasion. Tumors are generally hypercellular, but necrosis and hemorrhage can lessen this appearance. They are usually composed of right-angle intersecting bundles of spindle cells with elongated fascicular to hyperchromatic lobulated or indented nuclei with blunt ends (so-called cigar shape). Various patterns of the tumor cells may occur including palisading storiform and so-called hemangiopericytoma patterns, which of course give rise to a variety of difficulties in the differential diagnosis. Mitoses, both typical and atypical, are present in varying degrees as documented by Huang and Antonescu in their excellent review of 12 sinonasal smooth muscle tumors in 2003.10 They based the classification of these tumors on the guidelines for smooth muscle tumors of deep tissues using more than 4 mitotic figures per 10 high-power fields to separate leiomyomas from intermediate lesions with malignant potential, and those which were frank sarcomas. The latter group with more than 4 mitotic figures per 10 high-power fields were clearly what most would consider to be low-grade sarcomas. In contrast Kuruvilla et al concluded that the only significant prognostic indicator in sinonasal leiomyosarcomas was the extent of tumor involvement at presentation and not its histological grading.2 Huang and Antonescu10 suggested that histological grading still plays a role in the clinical behavior of sinonasal smooth muscle tumors as 2 of their 3 leiomyosarcomas, treated only with excision, were free of recurrence even when they had extensively involved both nasal cavity and paranasal sinuses. This latter report would certainly fit with the grading of soft tissue sarcomas in general, which helps to predict clinical aggressiveness.

Unfortunately, variations in histological appearances of leiomyosarcoma are not uncommon; they may be either focal or quite widespread and have led to considerable diagnostic dilemmas. Variable granularity may mimic a true granular cell tumor and osteoclastlike giant cells may lead to a diagnosis of giant cell malignant fibrous histiocytoma. There are myxoid variants of leiomyosarcoma and occasionally they may contain additional sarcomatous components with foci of apparent osteosarcoma and chondrosarcoma.

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