Human pathology
-
BRAF mutation is seen in a variety of human neoplasms including cutaneous malignant melanoma, papillary thyroid carcinoma, colorectal carcinoma, non-small cell lung carcinoma, pleomorphic xanthoastrocytoma, and others. Currently, there are 2 commercially available monoclonal antibodies for the detection of BRAF V600E mutation; however, a full and practical comparison of their performance in various tumor types on an automated staining platform has not been done. We investigated their sensitivity and specificity in detecting the BRAF V600E mutation in a series of 152 tumors including 31 malignant melanomas, 25 lung carcinomas, 32 gastrointestinal carcinomas, 23 thyroid carcinomas, 35 gliomas, and 6 other malignancies. ⋯ The sensitivity and specificity were 98% (60/61) and 97% (88/91) for monoclonal VE1 and 95% (58/61) and 83% (73/88) for anti-B-Raf, respectively. There were 4 cases with discordant IHC and mutational results for monoclonal VE1 in contrast to 18 cases for anti-B-Raf. Our studies showed that IHC with monoclonal VE1 has a better performance compared with anti-B-Raf in an automated staining platform and confirmed that clone VE1 provides excellent sensitivity and specificity for detecting the BRAF V600E mutation in a variety of tumor types in a clinical setting.
-
Granulomatosis with polyangiitis (GPA) (Wegener's) may mimic IgG4-related disease (IgG4-RD) on histologic examination of some biopsies, especially those from head and neck sites. IgG4 immunostaining is often performed in this context for differential diagnosis with IgG4-RD. Herein, we report the results of IgG4-positive (IgG4+) cells in 43 cases of GPA including 26 previously published cases as well as the newly added cases from the lung and kidney. ⋯ In conclusion, increased IgG4+ cells can be seen in sinonasal or orbital/periorbital biopsies of GPA, which could pose as a pitfall in the diagnosis of IgG4-RD. However, GPA in other organs and controls did not show increased IgG4+ cells when using the above threshold. The biologic or clinical importance of increased IgG4+ cells in GPA cases involving head and neck region is uncertain, and a further study might be warranted to address the potential pathogenic relationship between IgG4-RD and GPA in those cases.