IDH2 Mutations Define a Unique Subtype of Breast Cancer with Altered Nuclear Polarity.

Solid papillary carcinoma with reverse polarity (SPCRP) is a rare breast cancer subtype with an obscure etiology. In this study, we sought to describe its unique histopathologic features and to identify the genetic alterations that underpin SPCRP using massively parallel whole-exome and targeted sequencing. The morphologic and immunohistochemical features of SPCRP support the invasive nature of this subtype.

An endometrial stromal tumor with osteoclast-like giant cells.

Endometrial stromal tumors (ESTs) of the uterine corpus have a striking propensity to display diverse morphological variations, including sex cord-like, smooth muscle, or skeletal muscle differentiation; fibrous change; myxoid change; or bland endometrioid-type glands. They may also contain rhabdoid, foam, clear, or epithelioid/granular cells among others. Recently, we have encountered an EST showing smooth muscle differentiation and osteoclast-like giant cells that were predominantly concentrated in the areas showing smooth muscle differentiation.