Spindle cell oncocytoma of the pituitary gland

Case contributed by Dr Wen Jak Ma


Unrelated initial presentation with falls.

Patient Data

Age: 75 years
Gender: Female

Large (exceeding 1 cm) sellar region solid tumor with suprasellar extension. Heterogeneous hyperenhancement. Adenohypophysis and pituitary stalk are displaced anteriorly. Optic chiasm displaced and bowed superiorly.

The patient went on to have surgery. 


Moderately cellular. Proliferation of spindle cells with abundant eosinophilic, focally granular cytoplasm. Cells arranged in loose vesicular architecture, and in other areas in haphazard arrangement. Marked variation in nuclear size and shape, with numerous cells showing marked nuclear enlargement with irregular nuclear outlines and prominent nucleoli. No mitotic activity.

Lymphoplasmacytic cell infiltration. Large tumour cells seen to lie within neutrophil-like stroma.

Positive for: S-100, TTF-1, vimentin.

Very focal EMA staining. Patchy GFAP staining. Patchy and weak staining for CD68.

Negative for synaptophysin.

Variable Ki-67 index, but less than 5%.

Final diagnosis: Spindle cell oncocytoma. WHO Grade 1.

Comment: Granular cell tumour, pituicytoma, and spindle cell oncocytoma would all show evidence of pituicyte as the cell of origin. These 3 tumours may represent a morphologic spectrum of one entity. Spindle cell oncocytoma is the most likely of these lesions to show nuclear pleomorphism.

Case Discussion

On imaging, this would be called a pituitary macroadenoma more than 99.9% of the time.

Craniopharyngioma and, in this age group, metastasis, can be considered in the differential. The fact that the adenohypophysis and stalk are displaced anteriorly is unusual, but would probably not be sufficient to sway the diagnostician towards other extremely rare pituitary gland tumors.

The tumor has nevertheless succeeded in distracting the radiologists into missing the ACom aneurysm on multiple studies.

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Case information

rID: 54317
Published: 4th Jul 2017
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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