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Fig. 2.25 Ectopic pituitary adenoma. A Organoid growth pattern. B Growth in the form of ribbons. C Scattered mitotic figures are seen in a tumour that otherwise shows uniform neoplastic cells with minimal pleomorphism and dispersed chromatin. D Extension into bone may be present.

Fig. 2.25 Ectopic pituitary adenoma. A Organoid growth pattern. B Growth in the form of ribbons. C Scattered mitotic figures are seen in a tumour that otherwise shows uniform neoplastic cells with minimal pleomorphism and dispersed chromatin. D Extension into bone may be present.

ICD-O code 8272/0

Synonyms

Extrasellar pituitary adenoma; extrasellar adenohypophysial tissue; extracranial pituitary adenoma; sphenoidal pituitary adenoma; adenomatous pharyngeal pituitary.

Epidemiology

Ectopic pituitary adenomas of the upper aerodigestive tract are rare, and predominantly occur in adults but have been identified over a wide range of ages, from 16 - 84 years, with a reported mean and median age at presentation of 49 years and 58 years respectively {1425, 2752}. Females are affected more often than men {1425,2752}.

Etiology and pathogenesis

The etiology of ectopic pituitary adenomas is unknown. Extrasellar involvement by a pituitary adenoma can result from downward extension of a sellar-based pituitary tumour or occur as an adenomatous tumour arising from ectopic pituitary tissues. The latter may occur from two sources, including embryologic rests along the course of the cephalic invagination of Rathke's pouch (infrasellar) or anterior pituitary cells attached to the supradiagphragmatic portion of the pituitary stalk. This discussion will be limited to infrasellar-derived ectopic pituitary adenomas.

Localization

In the upper aerodigestive tract, ectopic pituitary adenoma most commonly occurs in the sphenoid bone and sinus {55,1425,1538,2627} and nasopharynx {417,488,2752}. Other sites of occurrence include the nasal cavity {1131, 2129,2752}, ethmoid sinus {2752}, and temporal bone {2129}.

Clinical features

The clinical presentation of ectopic pituitary adenomas is primarily related to its space- occupying effects, and include airway obstruction, chronic sinusitis, headache, epistaxis, cerebrospinal fluid leakage and visual field defects {237, 417,1425,1667,2627,2752}. Clinical evidence of hormonally active tumours can be identified in over half of the cases {1425} and include Cushing disease {235,309,1261,1538,2274,23 96}, acromegaly {491,685,2725} hyperparathyroidism {1538}, hyperthyroidism {488}, amenorrhea {1051}, and hirsutism {2752}. Radiographic imaging is helpful in localizing the lesion and determining the relationship to the sella turcica {2396}. Of note is the fact that the extent of tumour and erosion of bone do not completely correlate with severity of clinical signs and symptoms {1425}.] Furthermore, erosion of the sella turcica does not exclude an ectopic origin {1425}.

Macroscopy

Grossly, it is a polypoid and pedunculated mass ranging in size from 0.7-7.5 cm {1538}. It is usually solitary; rare examples may occur synchronously in separate sites {237}.

Histopathology

Ectopic pituitary adenomas are submucosal and unencapsulated cellular tumours with solid, organoid and trabec-ular growth patterns; tumour nests are separated by fibrovascular stroma. The neoplastic cells have round to oval nuclei with dispersed nuclear chromatin, inconspicuous to small nucleoli, and granular cytoplasm that can be eosinophilic, amphophilic or clear. Extracellular stro-mal hyalinization may be prominent. Nuclear pleomorphism, mitotic activity and necrosis are uncommon. The surface epithelium is intact and unremarkable. The tumour effaces the normal structures in the submucosa although residual sero-mucous glands can be identified.

Immunoprofile

Ectopic pituitary adenomas show strong cytoplasmic immunoreactivity for cytoker-atin, synaptophysin, chromogranin, neuron specific enolase, and may stain for a variety of pituitary hormones including adrenocorticotropic hormone (ACTH), prolactin, thyroid stimulating hormone (TSH), follicle stimulating hormone (FSH), growth hormone (GH), and luteinizing hormone (LH). Tumours may demonstrate immunoreactivity with only a single pituitary hormone (monohormonal pituitary adenoma), multiple hormones (plurihor-monal pituitary adenoma) or no pituitary hormone (null cell pituitary adenoma).

Electron microscopy

Intracytoplasmic secretory granules of varying numbers can be identified.

Prognosis and predictive factors

Surgical resection is the treatment of choice for smaller, accessible tumours {1425}; complete surgical eradication is usually curative {2752}. However, complete surgical resection may not be possible for larger, invasive tumours. When resection is incomplete or cannot be accomplished due to size and extent of

Fig. 2.26 Salivary gland anlage tumour. A The cellular tumour nodules communicate in the form of glandular structures with the surface epithelium. B There is merging of spindle cells into abortive tubules.

the tumour, postoperative radiotherapy is indicated {55,1425,2627,2666}. Dopa-mine agonist drugs (e.g., bromocriptine) have been effective in reducing the size (not permanently) in prolactin-secreting adenomas and the mitotic rate of other pituitary adenomas {1425}. Somatostatin analog treatment with octreotide has been shown to reduce tumour size and may, in the proper setting of a pituitary adenoma with high somatostatin receptor content, be administered in lieu of surgery in patients whose tumours are too large to be adequately resected {2093}. A rare example of malignant transformation of an ectopic pituitary adenoma has been reported {1131}.

Salivary gland anlage tumour Definition

A benign tumour with mixed epithelial and mesenchymal elements, recapitulating the early stages in the embryology of the salivary gland between the 4th and 8th weeks of development.

Synonym

Congenital pleomorphic adenoma Epidemiology

Fewer than 20 cases have been reported in the literature {229,233,296,572,1007, 1168,1720,1763}. Most patients are diagnosed in the immediate neonatal period or by the age of 6-weeks. Males exceed females by a 13:3 ratio.

Clinical features

Almost all patients present with respiratory and feeding difficulties. Bleeding has rarely been reported. Clinical examination reveals a midline pedunculated ery-thematous polyp {229}.

Macroscopy

A firm, smooth to lobulated mass measuring between 1.3 and 3 cm in greatest dimension is the typical gross appearance. The surface is usually glistening. The remnants of a stalk may or may not be apparent. A vague nodularity is appreciated on its greyish-tan to reddish cut surface. Cysts and interstitial haemorrhage may occur.

Histopathology

A non-keratinizing squamous mucosa overlies multiple contiguous cellular nodules. The nodules are separated by fibrous and myxoid stroma containing duct-like structures and nests of solid or cystic squamous epithelium. In areas, the duct-like structures are connected to the surface epithelium. The epithelial units within the internodular stroma blend into the cellular nodules, which are comprised of fusiform cells forming short fascicles or trabecular structures, interspersed with poorly formed tubules with or without lumens. The fusiform cells have eosinophilic cytoplasm with indistinct cell borders. The nuclei are bland and uniform, and mitotic activity is quite low. The interstitium can show haemorrhage, and rarely bone formation {296}.

Immunoprofile

The cellular nodules display a mixed pattern of reactivity for vimentin, cytokeratin and actin and are generally non-reactive for S-100 protein and glial fibrillary acidic protein. Nascent tubules and ducts within the stromal nodules show a luminal pattern of positivity for epithelial membrane antigen. The differentiated epithelial components are reactive for pancy-tokeratin and cytokeratin 7; epithelial membrane antigen positivity is restricted to the tubular structures. Salivary gland amylase is expressed consistently.

Prognosis and predictive factors

Complete excision is curative in virtually all cases.

Craniopharyngioma

ICD-O code 9350/1

Exceptionally, craniopharyngioma can arise in the nasopharynx or involves the nasopharynx through downward invasion from a suprasellar location. The morphological features are identical to the suprasellar counterpart {316,1609,1612, 2062,2083,2525}.

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