Spindle cell oncocytoma of pituitary

Case contributed by Dr Ernest Lekgabe


Presented with headache and bitemporal hemianopia.

Patient Data

Age: 30 years
Gender: Female

Well circumscribed slightly hyperdense pituitary fossa tumor with an expansion of the fossa and suprasellar extension.

Mildly T2 hyperintense pituitary fossa tumor with predominantly solid homogenous enhancement, expanding the fossa and with suprasellar extension. Mild flattening of the optic chiasm and optic nerves. No evidence of cavernous sinus invasion.

Post transsphenoidal resection of pituitary fossa tumor. Small volume blood products in the pituitary fossa. No evidence of post operative complication. 



Paraffin sections show fragments of a moderately hypercellular tumor. This is composed of plump spindle cells arranged in loose fasciculi in a fibrous and vascular stroma. A palisaded arrangement of nuclei is noted in some areas. No mitotic figures or areas of necrosis are seen. No normal anterior pituitary tissue is included.

Immunohistochemistry shows strong nuclear staining for TTF-1 in tumor cells and strong cytoplasmic staining for S-100 protein. No staining for GFAP, synaptophysin, SOX10 or epithelial membrane antigen (EMA) is seen in tumor cells. The topoisomerase labeling index is <1%. The features are of spindle cell oncocytoma.

DIAGNOSIS: Spindle cell oncocytoma.

Case Discussion

Spindle cell oncocytoma is a rare primary tumor of pituitary gland, not distinguishable from adenoma on imaging.

Interwoven fascicles of elongated spindled cells are typical on histology.

Lacks staining for cytokeratins, pituitary hormones or neuroendocrine markers.

Usually stains for S100 and thyroid transcription factor 1 (TTF1)


Histogenesis of the tumor is not completely understood, not clear if cell of origin is in the anterior or posterior pituitary.

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Case information

rID: 56180
Published: 16th Oct 2017
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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