Pituitary Adenoma - Erler Zimmer
Clinical History
A 29-year-old male presented with a 22-month history of headaches and blurred vision. Examination revealed a bi-temporal hemianopia and a left VIth nerve palsy. Skull X-ray showed erosion of most of the sphenoid body, with some dorsum sellae and anterior clinoid process intact. Carotid angiography displayed upward and lateral displacement of the anterior and middle cerebral arteries. Pneumoencephalography, a common imaging procedure used until the 1970s, showed upward displacement of the lateral and third ventricles from below. A craniotomy was performed, but the patient died immediately afterward.
Pathology
The brain specimen, sliced in the sagittal plane to the right of the falx cerebri, reveals the pituitary gland completely replaced by a round tumor, 4cm in maximum diameter. The tumor's cut surface is pale brown and homogenous, with an area of hemorrhage superiorly, likely caused by surgical trauma. The tumor has led to upward displacement of the midbrain, and erosion has destroyed the sphenoid bone, enlarging the sella turcica (arrow). The optic chiasma is compressed by the tumor. Histologically, this tumor was identified as a chromophobe adenoma arising from the anterior pituitary.
Further Information
This specimen is from an old case, and the investigations used would now be considered antiquated. Modern investigation would include an initial brain CT followed by an MRI of the brain to further visualize the pituitary lesion before any surgical intervention.
Pituitary adenomas are the most common pituitary tumor, typically found in adults with peak incidence between 35-60 years. Primary carcinoma of the pituitary is very rare, and the pituitary is an uncommon site for metastases. Clinical manifestations of pituitary adenomas are related to local mass effect and tumor function. Local effects include increasing intracranial pressure (headache, nausea, and vomiting), sellar expansion, bony erosion, and compression of decussating nerve fibers in the optic chiasma, causing bitemporal hemianopia.
Pituitary adenomas can be functioning (associated with hormone excess) or non-functioning (without clinical symptoms of hormone excess). About 75% of adenomas are functional, usually secreting prolactin, growth hormone, or ACTH. Secretion of TSH, LH, and FSH from pituitary adenomas is very rare. Some adenomas can secrete two hormones, with growth hormone and prolactin being the most common combination. Non-functional pituitary adenomas come to clinical attention later than those associated with endocrine abnormalities, and they may lead to hypopituitarism due to compression atrophy of the surrounding normal gland.
