ENT - 7. Diseases of the Salivary Glands PDF

Diseases of Salivary Gland Parotid Glands paired parotid glands are the largest of the salivary glands located in the parotid spaces Each gland is divided into a superficial lobe and a deep lobe with the posterior facial vein (retromandibular vein) approximating the location of the facial...

Diseases of Salivary Gland Parotid Glands paired parotid glands are the largest of the salivary glands located in the parotid spaces Each gland is divided into a superficial lobe and a deep lobe with the posterior facial vein (retromandibular vein) approximating the location of the facial nerve and serving as the radiographic landmark between the two lobes  main trunk of the facial nerve exits the skull base at the stylomastoid foramen pierces the posterior fascial border of the parotid space lateral to the surface of the posterior belly of the digastric muscle courses within the parotid gland lateral to the retromandibular vein  Approximately 80% of the parotid lies in the superficial lobe anterior and inferior to the external auditory canal deep lobe extends through the stylomandibular tunnel formed anteriorly by the ramus of the mandible and posteriorly by the stylomandibular ligament. parotid duct (Stensen duct) extends anteriorly from the superficial lobe of the parotid gland around the masseter muscle and anterior to the buccal fat, where it proceeds medially to pierce the buccinator muscle Submandibular Glands paired submandibular glands are visible posterior to the angle of the mandible largely within the submandibular space small deep portion curls up cranially around the posterior border of the mylohyoid muscle The submandibular duct (Wharton duct) exits the deep lobe and extends anteriorly and superiorly, medial to the sublingual gland in the sublingual space and terminating at the sublingual papilla in the floor of the mouth Sublingual Glands small, paired sublingual glands are positioned up against the sublingual depressions of the inner surface of the mandible just superior to the mylohyoid muscles Approximately 20 ducts (ducts of Rivinus) drain into the floor of the mouth Minor Salivary Glands numerous and are present in the deeper submucosal planes of the oral cavity, especially the lip and hard and soft palates, paranasal sinuses, pharynx, external auditory canal, and nose Imaging Computed tomography is the modality of choice for patients with inflammatory disorders of the salivary glands Magnetic resonance imaging is the modality of choice for patients with a palpable lesion or expected neoplasm of the salivary glands Ultrasound is useful in palpable salivary lesions and has been shown to assist the diagnostic accuracy of fine-needle aspiration Benign neoplasm of salivary gland  Salivary gland neoplasms are uncommon Representing less than 4% of all head and neck neoplasms Most salivary gland neoplasms occur within the parotid gland 80% are benign in adults 50% of submandibular gland and 20% of minor salivary gland tumors are benign palate is the most commonly affected minor salivary gland location. two theories of tumorigenesis have been proposed for salivary gland neoplasms bicellular stem cell theory (reserve cell theory) is currently the more commonly accepted theory It states that neoplasms arise from two populations of undifferentiated stem cells: the excretory duct reserve cell or the intercalated duct reserve cell. multicellular theory Less accepted theory which proposes that differentiated cells are capable of cell division Clinical Features present as painless, slowgrowing masses on the face for parotid tumors or at the angle of the jaw for submandibular tumors Minor salivary gland tumors most commonly occur on the palatal mucosa may be found incidentally and most are asymptomatic PE nontender, wellcircumscribed, and mobile tumors involving the parapharyngeal space, such as deep lobe parotid tumors unilateral aural fullness dysphagia obstructive sleep apnea “hot potato” voice Trismus may show a medially displaced oropharyngeal wall  Fine-needle aspiration biopsy - widely recognized and well established as a diagnostic tool in salivary gland neoplasms. Sensitivity- 85.5% to 99% specificity ranges-96.3% to 100% PLEOMORPHIC ADENOMAS also known as benign mixed tumors, are the most common neoplasms of the salivary gland most pleomorphic adenomas originate superficial to the facial nerve Pleomorphic adenoma of the minor salivary glands most commonly occurs in the palate The second most common site is the upper lip  Pathologically: solitary, firm, round tumors. The cut surface is characteristically solid and may be hard, rubbery, or soft in consistency with a whitish gray to pale yellow color Pleomorphic adenoma of the major salivary-encapsulated pleomorphic adenoma of the minor salivary glands- unencapsulated Management superficial parotidectomy Malignant transformation of pleomorphic adenoma- rare occurs most frequently in patients with long-standing tumors. The risk of malignant transformation in pleomorphic adenoma 1.5% within the first 5 years of diagnosis, but increases to 10% if observed for more than 15 years WARTHIN TUMORS second most common benign salivary gland neoplasm after pleomorphic adenoma has a male preponderance and is more prevalent in Caucasians compared to other racial groups accounts for approximately 10% of all parotid tumors found almost exclusively in the parotid gland or periparotid lymph nodes  Bilateral Warthin tumors occur in 10% of cases Associated with smoking present with an asymptomatic, slow-growing mass, often in the tail of the parotid gland Treatment of Warthin tumor is surgical excision (parotidectomy with facial nerve preservation) Malignant Neoplasms of the Salivary Glands Malignant neoplasms of the major and minor salivary glands are rare and represent approximately 3% of all head and neck malignancies Vast majority occur in the parotid gland mucoepidermoid carcinoma adenoid cystic carcinoma-22% Adenocarcinoma- 18% Malignant mixed tumor- 13% acinic cell carcinoma- 7% squamous cell carcinoma- 4% Mucoepidermoid Carcinoma most common salivary gland malignancy The majority of cases occur in the major salivary gland can also arise from minor salivary glands in the oral cavity hard palate buccal mucosa lip retromolar trigone  Slightly more common in women mean age of occurrence at approximately 45 years the most common pediatric salivary gland carcinoma Patients usually come to medical attention with a painless, slowgrowing mass  Microscopically, their hallmark is the presence of three cell types: mucous, squamoid (or epidermoid), and intermediate Adenoid Cystic Carcinoma one of the more common more recognizable salivary gland tumors, notorious for its infiltrative growth and a slow, progressive behavior with recurrences and spread over a protracted course of many years  occur with an even distribution across all salivary gland sites occur with an equal incidence in men and women  AdCCs are solid, light tan, firm, and wellcircumscribed but unencapsulated tumors Microscopically, three growth patterns have been described: tubular, cribriform, and solid tubular pattern consists of small tubules sitting in a pink, hyalinized, and hypocellular stroma solid pattern- has only rounded lobules of tumor cells with few, or no, gland-like structures and without a defined architecture Cribriform- The classic and most easily recognized pattern similar to Swiss cheese  perineural invasion- frequent histologic feature of AdCC metastases tend to be distant and most often to the lungs Acinic Cell Carcinoma Single, usually circumscribed, rubbery, solid mass Up to one-third show cystic degeneration Four principal histologic patterns are Solid/lobular Microcystic Papillary-cystic Follicular Acinic Cell Carcinoma Tumor with cells that show differentiation toward cells of the normal salivary gland acini More than 90% occur in the parotid Second most common childhood salivary gland malignancy Manifestations: Slowly growing mass Occasionally painful Rarely associated with facial palsy Acinic Cell Carcinoma Classic features: Characteristic has blue cytoplasm with abundant serous-type granules and a small, round, centrally placed nucleus Dense lymphoid infiltrate with germinal centers The differential diagnosis includes normal parotid gland FNA biopsy of ACC is difficult because of its frequent resemblance to  Acinic Cell Carcinoma Treatment Surgical resection with negative margins 10% to 15% of these tumors will metastasize locally to regional lymph nodes or distantly to the lung and bones Survival is approximately 80% at 5 years and 70% at 10 years  Thank you