Pituitary Macroadenoma

Clinical History

A 45 year old male patient presented with gradual onset progressive visual loss since last two years. He also complains of occasional headache since last four months.

Imaging Findings

A 45 year old male attended our hospital out patient department with history of gradual onset visual loss. On examination bitemporal hemianopia was found. He was subjected to MRI scan of brain which revealed an approximately 55x41 mm sized lobulated solid mass lesion in the sellar region with extension into the supra and parasellar region, more towards right side giving a “figure eight” like appearance . The lesion has pushed the third ventricle upward and also partly invaded both cavernous sinuses with extension into right temporal lobe. The lesion is isointense in T1WI, T2WI and in FLAIR images. Mild to moderate degree of slightly nonhomogenous and rim enhancement seen after gadolinium injection. A mega cisterna megna seen in posterior fossa. Post operative images at the end of four weeks have shown enlarged sella filled with CSF. At the bottom of sella iso and hyperintense tissues seen suggesting muscle and fat graft taken from thigh.

Discussion

Pituitary gland is composed of different variety of hormone producing cells. Adenomas are therefore may be of different types depending upon the involvement of types of cells. Again adenomas are divided into micro and macroadenoma depending upon their sizes. Microadenomas are 10 mm or less, whereas macroadenomas are more than 10 mm in diameter.
Pituitary adenomas accounting for approximately 10% of all primary intracranial neoplasms. Macroadenomas are twice as common as microadenomas. Pituitary macroadenoma is the single most common suprasellar tumor, accounting for one third to one half of all lesions in this area.
Age and gender incidence vary according to tumor type. More than 90% adenomas occur in adult population. Prolactinomas have a 4-5:1 female preponderance and typically seen in young adults. Corticotrophic tumors occur in women. Growth hormone secreting tumors have a 2:1 male preponderance.
Depending upon the involvement of types of cells adenomas are typed into prolactinoma, growth hormone cell adenoma, mixed growth hormone and prolactin cell adenoma, corticotroph adenoma, “Silent” corticotroph adenoma, gonadotroph adenoma, thyrotroph adenoma, plurihormonal adenoma and null cell adenoma.
Prolactinoma are the most common pituitary adenoma accounting for 30% of all pituitary adenomas. At least half of all prolactinomas are microadenomas. These tumors typically cause amenorrhea and galactorrhea in young women. Whereas in men it occurs at an older age group and are often endocrinologically silent and may attain very large size and are associated with very high prolactin levels. Growth hormone adenomas are the second most common type accounting for 15% of all pituitary adenomas and are the most common type of endocrinologically active adenomas and cause gigantism. Corticotroph adenoma constitutes 5-10% of adenoma. Endocrinologically active adenomas may secrete ACTH and may cause Cushing disease or Nelson syndrome. Gonadotroph and thyrotroph adenoma are less common and they commonly produce microadenoma. Null cell adenomas (including oncocytoma) are endocrinologically silent tumor though they produce some amount of different types of hormones which are too little to produce symptoms. They may attain very large size and are generally symptomatic due to their size.
Macroadenomas give a variable appearance on imaging. Most are isodense/ isointense with gray matter on non-contrast CT scan/ MR with moderate enhancement on post contrast study which is often non-homogenous especially in MR images. Calcification seen in 1-8% cases. Presence or absence of necrosis, cyst formation and hemorrhage gives different appearance in CT and MRI. Invasion of adjacent structures such as cavernous sinus is reportedly more common with prolactin or growth hormone producing tumors than non-secreting tumors. In the present case the macroadenoma has partly invaded both cavernous sinuses, however this one came out to be non-secreting macroadenoma. On imaging alone, invasive adenoma cannot be distinguished from rare pituitary carcinoma.
Prognosis is good as more than 99% cases are benign. However, recurrence rate is high in symptomatic adenomas and reported to be 16% at 8 years and 35% at 20 years.

Differential Diagnosis List

Final Diagnosis

Pituitary macroadenoma

URL:	https://www.eurorad.org/case/7515
DOI:	10.1594/EURORAD/CASE.7515
ISSN:	1563-4086