Histopathology
Microscopy shows mostly necrotic tissue and haemorrhage together with small areas of viable cells showing a sinusoidal pattern composed of monomorphic epithelioid cells. A reticulin stain shows expanded nests of cells in these areas.
Immunohistochemistry shows the viable tumour cells express pancytokeratin, very occasional cells showing ACTH and focal expression of FSH. Alpha subunit, LH, prolactin, TSH, GH are negative. The proliferation index, shown with MIB1, is low.
Diagnosis
Overall the appearances are of a pituitary adenoma together with pituitary apoplexy in keeping with the clinical impression. The viable adenoma appears to focally express FSH and is, therefore, a probable gonadotroph cell adenoma.
Pituitary lesion - Probable gonadotroph cell adenoma together with pituitary apoplexy.