Monday, August 1, 2016

The utility of TTF-1 immunohistochemistry in the diagnosis of sellar region masses

Posterior pituitary cells (pituicytes) manifest nuclear TTF-1 positivity. Anterior pituitary cells are negative. Three rare neurohypophyseal neoplasms which are derived from pituicytes maintain TTF-1 nuclear positivity: pituicytoma, spindle cell oncocytoma, and granular cell tumor. At times when the neuropathologist is trying to distinguish one of these neoplasms from more common sellar tumors -- such as pituitary adenoma, meningioma, and schwannoma -- TTF-1 can be helpful.

TTF-1 immunohistochemistry in the neurohypophysis


Eddie Lee said...

As a fellow, I got a case diagnosed as a pituitary adenoma but I realized was actually a TTF1 positive lung metastasis. This led to the question of whether the pituitary expressed TTF1. A literature search revealed that TTF1 is called NKX2.1 by basic scientist and is expressed in the neurohypophysis (and that TTF1 knockout leads to agenesis of the lung, thyroid and pituitary). A few IHC stains later, we now know that TTF1 labels neurohyphyseal (and other ventral neuroectodermal) tumors.

Brian E. Moore, MD, MEd said...

Eddie Lee's excellent comment adds another entity to the ddx of TTF1+ sellar tumors that I did not mention: metastasis.