Ossifying pituitary adenoma co-existing with astrocytoma and pituitary adenoma associated with gangliocytoma: two unusual conditions.

Bone formation in pituitary adenoma is an extremely rare finding. Only five previous cases have been published. This is the sixth case report of an ossifying pituitary adenoma and the first case report of a pituitary adenoma with bone formation coexisting with WHO grade II astrocytoma. MRI imaging revealed an unusual eggshell cap-like calcified structure surrounding the tumor. Histologically, the adenoma contained irregularly anastomosing trabeculae with well-formed lacunae and osteoblasts along the margins. Our second case concerns a 25-year-old male patient who presented with complains of off and on headache for 12 months. MRI (head) revealed a 4x3cm well defined rounded lesion in the sella and suprasellar extension that was isointense in T1, hyperintense on T2 with cystic areas and homogenous contrast enhancement. On morphological examination, a cellular tumor admixed with foci of large ganglion cells embedded in a neuropil stroma was noted. On immunohistochemistry, tumor cells were focally positive for pancytokeratin, growth hormone and synaptophysin; and ganglion cells were positive for neurofilament and synaptophysin. No GFAP positive cells were seen. The Ki67 index was < 1%. Based on these findings, a diagnosis of gangliocytoma associated with pituitary adenoma was considered.