Presentation
Visual failure.
Patient Data
A large relatively homogeneous mass expands the pituitary fossa, bulges into the left cavernous sinus, as extends into the suprasellar cistern elevating and compressing the optic chiasm. The mass demonstrates homogeneous contrast enhancement.
The patient went on to have the tumor resected.
MICROSCOPIC DESCRIPTION: The sections show fragments of a moderately hypercellular adenoma. The tumor cells have moderately pleomorphic round and oval hyperchromatic nuclei and a variable amount of pale cytoplasm. These are arranged in diffuse sheets intersected by thin walled capillaries. An occasional mitotic figure is identified. No areas of necrosis are seen. A narrow rim of normal anterior pituitary tissue is seen at one edge of the tumor. Immunohistochemistry shows strong cytoplasmic staining in tumor cells for TSH. There is also moderate staining for cytokeratin CAM 5.2. No staining for growth hormone, prolactin, ACTH, FSH or LH is seen in tumor cells. The features are of a thyrotroph cell adenoma. The topoisomerase labeling index is approximately 3%.
FINAL DIAGNOSIS: Pituitary tumor: Thyrotroph cell adenoma.
Case Discussion
TSH secreting macroadenomas are rare. Macroadenomas in children are also rare. A TSH secreting macroadenoma in a 13-year-old is therefore very rare indeed.