Neuron precursor features of spindle cell oncocytoma of adenohypophysis.

CONTEXT: Spindle cell oncocytoma of the adenohypophysis (SCO) is a non-endocrine neoplasm with few recurrent forms described. It arises from the folliculo-stellate cells of the adenohypophysis.

OBJECTIVE

We describe a case of SCO in a 24-year-old woman and provide pathogenetic information.

DESIGN

Hematoxylin-eosin (H&E), and immunohistochemistry, with controls, for S100, SMI-311, neurofilament, EMA, CD68, GFAP, chromogranin, synaptophysin, and Ki67 were performed. CD44, nestin, Gli2, p-Akt(Ser 473) and p-mTOR(Ser 2448) antibodies were applied, and each analyte's cellular distribution and intensity were noted.

RESULTS

H&E showed a proliferation of spindle and polygonal cells with a fascicular pattern, without mitoses. There was reactivity for SMI-311, CD44, nestin, S100, EMA, and vimentin. Neurofilament, CD68, chromogranin, synaptophysin, and GFAP were not expressed. p-Akt and p-mTOR were expressed suggesting mTORC2. Gli2 showed nuclear expression in the tumoral cells.

CONCLUSIONS

These findings suggest that SCO has neuron-like precursor cells. Sonic hedgehog and mTOR pathways are activated.