8.1
Pediatric Salivary Gland Neoplasms
Salivary neoplasms are uncommon in children. They may arise in the acini and ducts (epithelial tumors) or in mesenchymal tissue, e.g., the intraparotid lymphoid (lymphoma) or connective tissue (neurofibroma, schwannoma, rhabdomyosarcoma). They may be benign or malignant. Head and neck tumors of non-salivary origin may infiltrate the salivary glands, and the most common tumors encountered in children are lymphovascular lesions, which may be locally aggressive and rapidly proliferate, but are not true neoplasms.
Vascular Anomalies
Infantile Hemangiomas
Infantile hemangiomas are the most common tumors of the salivary glands in children. Some 90% occur in the parotid, usually presenting within a few weeks of birth. They follow a proliferative phase for 6–9 months, followed by involution, usually completed by 3–5 years. Most have extensive cutaneous involvement such that the diagnosis is clinically obvious, but some present as a palpable mass or an area of focal swelling with normal overlying skin. They cause a great deal of parental anxiety and are often thought to represent advanced malignancy, but imaging will show the characteristic appearance ( Figs. 8.1.1 , 8.1.2 ) and avoid the need for biopsy. Hemangiomas can usually be observed with no active medical or surgical intervention. Resolution can be hastened by the use of systemic propranolol. A small number of highly proliferative cases show rapid proliferation – e.g., Kaposiform hemangioendothelioma, an intermediate between a hemangioma and a malignant angiosarcoma – and in some cases there is extensive swelling encroaching on the orbit, or infiltrating the airway. Treatment with chemotherapy agents such as methotrexate, under the supervision of a pediatric oncologist, may be offered in these rare cases.
Lymphatic Malformations
Lymphatic malformations may originate within the parotid (Type 1) but more often the gland is infiltrated by a lymphatic malformation of the surrounding tissue (Type II). The majority of patients with lymphatic malformations present at birth or within a few months, but cases have been diagnosed in late childhood and into adulthood. The typical presentation is of a painless, soft, fluctuant mass. Their growth is generally in proportion to the patient’s body growth, but infection and bleeding can lead to an acute increase in size. Clinical examination alone is insufficient to identify the extent, especially in the deep portion of the parotid gland. Sonography is useful but the deeper invasive disease is best shown by MRI. A T2-weighted image will enhance the malformation very effectively. Complete excision via a partial or total parotidectomy with facial nerve preservation is the method of choice for type I lymphatic malformation of the parotid gland. Preservation of the facial nerve should be achievable in all cases, but the nerve is often elongated and its course is aberrant as the malformation encompasses, deflects or buries it. Type II malformations may be more complex. Complete excision as a one-stage procedure is most likely to achieve complete eradication, but attempts to completely remove the deep infiltrative malformation may result in a serious functional deficit, and sclerosing agents, usually administered under the supervision of an interventional radiologist, are becoming more widely used either alone or as an adjunct to surgery.
Neoplasms
Benign Epithelial Tumors
Benign epithelial tumors typically present as a painless, palpable, asymptomatic, slow-growing mass. Minor salivary gland neoplasms, though rare, have been reported in children. As in adults, the commonest benign tumor is the pleomorphic salivary adenoma (PSA). Parotid gland PSAs occur most commonly in the lateral lobe, followed by the deep lobe and the parapharyngeal space. They occur in children as young as 1 year old, but the mean age in children is 15 years. Investigation and management is similar to adult practice, but fine needle aspiration (FNA) is less reliable in children, who may not tolerate it well. Imaging is an essential part of the work-up, but MRI scanning in children will often require a general anesthetic.
Malignant Epithelial Tumors
Malignant epithelial tumors are rare in children, with an incidence of 1 per million population. Parotid tumors in children cause a great deal of anxiety and it is often said that the proportion of malignant-to-benign tumors is higher in children than in adults, but a recent National Cancer Registration-based report from Denmark reports that this was not so. Most cases present in the second decade of life, but if such a tumor presents in a child under 10 years old, then it is more likely to be of a high grade with a poorer prognosis. Approximately 50% will report pain, and occasionally there is facial nerve palsy or tethering of the skin. Mucoepidermoid carcinoma is the most common (50%) followed by acinic cell (35%), with adenocarcinoma and adenoid cystic carcinoma accounting for most of the rest.
Mesenchymal Tumors
Mesenchymal tumors such as benign neuroblastoma, schwannoma, and primary neuroectodermal/Ewing sarcoma can also present. The salivary glands in children – particularly the parotid – have a high proportion of lymphoid tissue, and head and neck lymphomas not infrequently involve the parotid gland. Diagnosis can be delayed in children due to the rarity of these lesions and because they are assumed to be “reactive lymph nodes”. Rhabdomyosarcomas (RMS) are the most common malignancies of the head and neck in children, and not infrequently involve the salivary glands ( Figs. 8.1.3 , 8.1.4 ). They are designated by their location, and involvement of salivary glands is classified as “non-orbital, non-parameningeal”. RMS usually affects young children and adolescents, with most cases occurring before the age of 10 years. All three histologic variants of RMS have been reported as affecting salivary glands: embryonal (most common), spindle cell, and alveolar (the poorest prognosis). The presenting signs and symptoms may include a slow-growing facial lump, and pain while eating or chewing. There may be a facial palsy. Initially, the overlying skin appears normal, but as the tumor progresses in size, changes including ulceration become obvious. Diagnosis and staging involves imaging: ultrasound, CT, and MRI. Tissue diagnosis is essential and usually requires open biopsy. Genetic testing on the tissue helps to classify the pathologic group and aids the selection of treatment.
Treatment
Benign tumors are managed much as in adults. Parotid surgery in children is especially challenging due to the small size and superficial position of the facial nerve. Bony landmarks, e.g., the mastoid process and the stylomastoid foramen, are less well-defined. Malignant tumors may involve a treatment combination of surgery, chemotherapy, and radiotherapy. Surgery has little role in the management of lymphoma or RMS, other than in diagnosis. Radiotherapy is increasingly important in pediatric oncology with proton therapy assuming a greater role in recent years. Malignant tumors are managed under the supervision of a pediatric oncologist with the support of a multidisciplinary team (MDT), and survival figures for pediatric malignancies are improving rapidly.
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Hemangioma is the commonest congenital mass found in the parotid.
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Imaging is essential. Multidisciplinary teams have improved prognosis.
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Fine needle aspiration is of limited use in pediatric tumors.
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The facial nerve may be very superficial and is easily vulnerable to iatrogenic trauma in children.
8.2
Pediatric Salivary Gland Inflammatory Conditions
Pediatric Salivary Inflammatory Diseases
Inflammatory disorders/diseases may involve the parenchymal tissue (acini and ducts) causing a true sialadenitis of one or more of the major or the minor salivary glands, or as in the case of connective tissue disorders such as Sjögren syndrome, there may be a generalized pan-sialadenitis . Viral infections of the parotid tend to be bilateral, as in mumps; bacterial infection tends to affect a single gland, e.g., acute suppurative parotitis or parotid abscess. Salivary glands in children, especially the parotid, contain lymphoid tissue interspersed between the ductal and acinar tissue. Lymph nodes are intimately related to the capsule of the submandibular gland. Swellings in the parotid or submandibular area may be due, not to parenchymal salivary disease, but to lymphadenopathy. Parotidomegaly in a child should raise suspicion of lymphoid pathology.
Acute Viral Sialadenitis
Viruses, e.g., mumps, coxsackie virus, echovirus, cytomegalovirus (CMV), and HIV, can present with acute enlargement of one or more salivary glands. Mumps – a once-common childhood infection caused by a paramyxovirus – is now rare in developed countries where the mumps, measles, and rubella (MMR) vaccination is widely available but outbreaks still occur, especially in adolescence. Presentation is with a mild febrile illness and bilateral enlargement of the parotid glands. The child is often fractious with fever and trismus. The parotid duct papillae may be swollen.
Mumps is usually a benign childhood illness with uneventful recovery but aseptic meningitis, encephalitis, and acute pancreatitis are potentially fatal complications. Orchitis can lead to infertility in boys, and is still an important cause of sensorineural deafness, particularly in parts of the developing world where vaccination rates are low.
HIV Infection in Children
HIV infection in children (see Chapter 9.3 ) may be complicated by enlargement of the parotid glands, typically bilateral. There is infiltration of lymphocytes, with follicular hyperplasia of intraparotid lymphoid tissue and the development of lymphoepithelial cysts. Ultrasound scanning may show multicystic intraparotid disease and should alert the clinician to the possibility of HIV infection acquired in the perinatal period.
Bacterial (Pyogenic) Sialadenitis
Bacteria may infect the salivary glands, particularly if there are predisposing factors such as stasis of secretions, ectatic ducts and acini, and dental or gingival sepsis. Children with reduced immunity, e.g., premature infants and children receiving chemotherapy for malignant disease, are especially at risk. Pyogenic organisms such as Streptococcus pyogenes , Haemophilus influenza and Staphylococcus aureus predominate, but anaerobic organisms and a host of unusual and antibiotic-resistant organisms may be implicated (see Chapter 7.1 ). Acute suppurative sialadenitis most frequently involves the parotid gland ( Fig. 8.2.1 ).
Treatment is initially medical and involves hydration, analgesics, and IV antibiotics. Infection may track beyond the gland and give rise to parapharyngeal abscess, or in the case of the submandibular gland a spreading cellulitis (Ludwig’s angina). Abscess formation and failure to respond to antibiotics will require surgical drainage. An acute abscess can be decompressed by needle aspiration. Should the abscess persist or be deeply seated, then formal open drainage may need to be performed. To decompress a parotid abscess, a preauricular incision is best. The parotid fascia is incised parallel to the facial nerve, bearing in mind the extremely superficial position of the facial nerve in children . For a submandibular gland abscess use a standard submandibular approach, taking care not to traumatize the marginal mandibular nerve. In both cases a drain may be needed.
Intrasalivary Lymphadenopathy
Acute Lymphadenitis
Enlargement of the neck lymph nodes in childhood is a normal feature of the developing immune system and will often involve the intraparotid nodes, causing transient parotidomegaly. Pathologic cervical lymphadenitis can result from pharyngeal or sinonasal sepsis and progress to a coalescent mass of necrotic tissue within the capsule of the gland. Pyogenic organisms such as Staphylococcus aureus and Streptococcus pyogenes are usually to blame. This can become intensely painful and may need drainage in the same way as an intraparotid parenchymal abscess.
Granulomatous Infection
Mycobacterium tuberculosis infection of the neck is still common, particularly in the developing world. It may involve nodes adjacent to and within the parotid and submandibular glands. Non-tuberculous mycobacterial (NTM) infection of the neck is now far more common in Western communities. It mainly affects otherwise healthy children between 1 and 3 years of age. The responsible organisms ( Mycobacterium avium-intracellulare , Mycobacterium kansasii , and Mycobacterium scrofulaceum ) are widely distributed in soil and rarely cause pathology in older children or in adults. The condition is sometimes termed atypical mycobacteria (ATM) or environmental mycobacteria . The glands enlarge painlessly and the child is generally perfectly well other than that the parents notice a neck swelling ( Fig. 8.2.2 ). As the disease progresses, lymph nodes coalesce, there may be central liquefaction with superimposed infection and abscess formation, and the overlying skin develops a characteristic discoloration. It may break down to cause an unsightly wound. Ultrasound ( Fig. 8.2.3 ) and MRI – if available – will help to delineate the extent of involvement. Histologic diagnosis will show non-caseating necrotic granulomatous tissue, but culturing the organism is notoriously difficult. Spontaneous resolution over a period of several months can be expected, even with no treatment. The infection is not transmitted by direct contact and the child can continue to go to school during the active phase of the disease. If there are loculi of infection or abscess formation, this can be dealt with by aspiration under a short general anesthetic. Surgery is often considered but the position of the involved glands and the state of the overlying skin are such as to present a significant risk to one or more of the branches of the facial nerve. Surgery – by incision and drainage with curettage or full excision if it can be done safely – is reserved for extensive disease or where there is impending or established skin necrosis. Chemotherapy using a combination of macrolide antibiotics and anti-tuberculous medication can be offered to hasten resolution, but many prefer a “watch-and-wait” approach. The esthetic result is usually excellent but the scarring may take many months to resolve.
Cat-scratch disease ( Fig. 8.2.4 ) is a granulomatous lymphadenitis caused by Bartonella henselae . Infection occurs through a scratch or bite from a cat or kitten. Most cases involve the lymph nodes and skin surrounding the parotid and submandibular glands. Aspiration and microscopy can be helpful to identify the organism. Management is symptomatic. The adenopathy generally resolves in a few months.
Actinomycosis involving the salivary glands is rare in children. It usually presents as a painless, slowly growing hard mass that develops multiple sinus tracts. On imaging, multiple areas of necrosis can be seen. The presence of sulfur-like granules in the purulent discharge, aspirate, or tissue biopsy, is pathognomonic for the disease. Treatment includes surgical drainage or excision and long-term (6–12 months) antibiotics (penicillin, clindamycin, or tetracycline).
Non-Infective Sialadenitis
Sarcoidosis may affect the parotids. A number of disorders, which give rise to cervical adenopathy and are often initially thought to represent lymphoma, may present in the salivary glands. These are sometimes referred to as the “pseudolymphomas”. They include Kimura disease – a rare chronic inflammatory disorder involving subcutaneous tissue and frequently associated with head and neck lymphadenopathy and/or salivary gland enlargement. Kawasaki disease is an acute inflammatory vasculitis of early childhood, presenting with fever, rash, unilateral cervical lymphadenopathy, and coronary artery disease. Rosai–Dorfman syndrome is a self-limiting rare disorder characterized by proliferation of histiocytes within lymph nodes. Langerhans cell histiocytosis is another variant ( Fig. 8.2.5 ). These conditions are usually diagnosed histologically when a salivary gland mass has been excised for suspected neoplasia.
