Sellar and Suprasellar Tumors

10% to 15% of all intracranial tumors

Annual incidence: 0.2 to 2.8 cases per 100,000

About 20% to 30% of pituitary adenomas are nonfunctioning (nonsecretory)

Hormone-secreting adenomas: prolactin (PRL) 25%, growth hormone (GH) 20%, and adrenocorticotropic hormone (ACTH) 10%, gonadotropins (follicle-stimulating hormone/luteinizing hormone; FSH/LH) 10% to 15%, thyroid-stimulating hormone (TSH) 1% to 3%

Most are sporadic

About 3% are associated with multiple endocrine neoplasia type I (11q13 mutation): pituitary, pancreas, and parathyroid gland tumors

Typically slow growing

General symptoms: headache, facial pain, numbness, lack of energy, weight loss, nausea, vomiting

Symptoms resulting from mass effect:

• Bitemporal hemianopia resulting from compression of the optic chiasm

• Lateral expansion can also compress the abducens nerve, causing lateral rectus palsy

• “Stalk effect” = elevation in prolactin, without an actual prolactinoma

“Pituitary apoplexy” most often caused by hemorrhagic necrosis of a pituitary adenoma resulting in sudden severe headache and visual loss; potentially fatal with adrenal failure caused by ACTH deficiency

• Sheehan syndrome: Pituitary gland apoplexy (not related to adenoma) in which postpartum hemorrhage causes infarction of the pituitary gland, leading to hypopituitarism

Symptoms caused by specific hormone production:

• PRL: amenorrhea, irregular periods, galactorrhea, infertility or hypogonadism, loss of libido, and impotence in men

• GH: gigantism in children; acromegaly in adults

• ACTH: Cushing disease (increased fat deposition, striae, bruising, diabetes, fatigue)

• TSH: thyrotoxicosis (heat intolerance, sweating, tachycardia, fine tremor, weight loss)

• Gonadotrophins—LH or FSH: amenorrhea or impotence in males

• Occasional “bihormonal” adenomas: GH and prolactin most common

“Invasive adenoma”: may grow into base of brain, cavernous sinus, sphenoid sinus

Potentially aggressive variants:

• Crooke's cell adenoma usually present as functional macroadenomas with increased risk of invasion, recurrence

• Sparsely granular GH-producing adenoma with fibrous bodies: may show rapid growth, invasion and resistance to somatostatin therapy

Pituitary carcinoma:

• Rare aggressive tumor defined by metastasis

Surgical: transsphenoidal resection (endoscopic transnasal approach)

Medical: prolactinomas treated with bromocriptine or cabergoline (dopamine receptor agonists); growth hormone–producing tumors treated with somatostatin analogues (such as octreotide)

Radiation therapy reserved for residual, recurrent, or invasive tumors

Pituitary apoplexy: emergent surgical decompression, glucocorticoids, close monitoring

Circumscribed, variably enhancing lesions

Macroadenomas expand the sella

Some adenomas may be less contrast enhancing than the adjacent pituitary gland

Circumscribed, nonencapsulated, tan-brown tumor

Macroadenoma >1 cm

Microadenoma <1 cm

Loss of normal lobular architecture of adenohypophysis

Adenomas form sheets and cords of monomorphic cells

• Random nuclear pleomorphism or binucleation often present

• Well-defined cell borders and eosinophilic granular cytoplasm

• Discohesive monomorphic cells on touch preparation

May show marked variation in architecture and mimic other tumor types such as ependymoma, oligodendroglioma, and metastatic epithelial tumors

Basophilic granules in ACTH-producing types

• Crooke's cell adenoma: perinuclear accumulation of cytokeratin that displaces ACTH-containing granules

Eosinophilic cytoplasmic granules in GH producing types

• Sparsely granular GH-producing adenomas with fibrous bodies have spherical inclusion-like cytoplasmic accumulations of cytokeratins (CAM5.2)

Focal atypia (pleomorphism) does not equate with malignancy:

• No well-defined histopathologic criteria for invasive types or carcinoma

Loss of normal lobular adenohypophyseal architecture well demonstrated by reticulin stain

Chromogranin, cytokeratin (especially CAM5.2), epithelial membrane antigen (EMA) immunoreactive

Nonsecreting tumors usually negative for all adenohypophyseal hormones

Secreting tumors diffusely reactive for one of the adenohypophyseal peptide hormones: prolactin (distinct perinuclear granular reactivity), GH, ACTH, FSH, LH, or TSH

Further subclassification of pituitary adenomas by electron microscopy: acidophilic stem cell type, null cell adenoma, oncocytic variant

Pituicytoma

Spindle cell oncocytoma

Craniopharyngioma

Granular cell tumor

Sellar meningioma or schwannoma

Rathke cleft cyst

Germ cell tumors

Metastasis

Hypothalamic gliomas, hamartomas

Carotid-cavernous fistula, aneurysm

Lymphocytic or granulomatous hypophysitis

Possibly derived from neurohypophyseal pituicytes—specialized, supportive glial cells of the infundibular stalk and neurohypophysis

Rare, <50 cases

Arise in adults: age range is 30 to 83 years

More common in men

Sellar or suprasellar, arising from infundibulum or posterior pituitary gland

Visual symptoms, headaches, or hypopituitarism

Total resection; may recur if incompletely excised

Solid, discrete, contrast-enhancing sellar or suprasellar mass