Figure 3.

Sparsely-granulated somatotroph tumor. (a) These tumors are composed of chromophobic cells with marked nuclear pleomorphism that is attributed to the nuclear distortion induced by large pale globular structures in the tumor cell cytoplasm. (b) The nuclei are highlighted by staining for Pit1 that demonstrates the irregular nuclear contours. (c) Growth hormone reactivity is scant and faint. (d) The tumor cells exhibit a peculiar reactivity for keratins using the Cam 5.2 antibody; the keratins aggregate into round dense fibrous bodies that are the hallmark of this tumor type.