Monday, December 10, 2018

A Pattern-Based Approach to the Interpretation of Skeletal Muscle Biopsies

Chunyu (Hunter) Cai, MD, PhD
Chunyu (Hunter) Cai, Douglas Anthony, and Peter Pytel have authored a wonderfully useful review article in Modern Pathology entitled A Pattern-Based Approach to the Interpretation of Skeletal Muscle Biopsies. Dr. Cai wrote the following to me: "In this review, we take a pathology-friendly approach and categorize muscle biopsies into 6  morphologic groups, and discuss common differential diagnoses for each group. I think this review fills a void that there is not a good quick guide for NP fellows, residents and even neuropathologists who don’t sign out muscle cases on a routine base." Thanks, Drs. Cai, Anthony, and Pytel for a review article that will be a fixture on the desks of many neuropathologists in the coming years!

Tuesday, December 4, 2018

Giant cell GBM masquerading as an anaplastic PXA

At first glance, this tumor with pleomorphic cells and prominent perivascular lymphocytic cuffing strikes one as a pleomorphic xanthoastrocytoma (PXA).

The relative circumscription, as demonstrated by the stark difference in tumor burden in adjacent gyri depicted above also suggests the possibility of  PXA.

The presence of mitotic figures (center of picture above) and a small amount of necrosis and microvascular proliferation (not pictured) suggests the possibility of anaplastic PXA.

However, perivascular lymphocytes and relative circumscription can be seen in giant cell glioblastoma (GC-GBM). Pointing away from anaplastic PXA is the fact that there was no evidence of Rosenthal fibers and eosinophilic granular bodies. Additionally, there was strong p53 immunohistochemical positivity. The final diagnosis was Glioblastoma, IDH-wildtype, WHO grade IV, giant cell variant.