Comparison of Immunohistochemical Expression of Cytokeratin 19, c-KIT, BerEP4, GATA3, and NUTM1 Between Porocarcinoma and Squamous Cell Carcinoma.

ABSTRACT: Distinguishing porocarcinoma from squamous cell carcinoma (SCC) is clinically significant; however, differential diagnosis can often be challenging. This study sought to confirm the diagnostic utility of cytokeratin 19, c-KIT, BerEP4, GATA3, and NUTM1 immunohistochemistry in distinguishing porocarcinoma from SCC. Immunohistochemical analysis of cytokeratin 19, c-KIT, BerEP4, GATA3, and NUTM1 in 14 porocarcinomas and 22 SCCs was performed; the extents and intensities of expression of these markers were recorded. The statistical associations of the immunoexpression between porocarcinoma and SCC were analyzed using the Pearson χ2 test. Cytokeratin 19 was positive in 13 (92.9%) of 14 porocarcinomas, and for all the positive cases, staining was strong and evident in >20% of the tumor cells. By contrast, 9 (40.9%) of 22 SCCs expressed cytokeratin 19 (P = 0.0018), of which 6 showed extremely focal (≤10% of the tumor cells) expression. Of the 14 porocarcinomas, 11 (78.6%) cases showed c-KIT positivity, whereas only 3 of 22 SCCs (13.6%) expressed c-KIT focally (P = 0.0001). In addition, BerEP4 immunostaining differed between porocarcinomas and SCCs (57.1% vs. 9.1%, respectively; P = 0.0017). However, no significant difference between the groups was reported in terms of GATA3 expression (57.1% vs. 72.7%, respectively; P = 0.3336). NUTM1 was expressed in 4/14 (28.6%) porocarcinomas but not in the SCCs. Immunohistochemistry for cytokeratin 19, c-KIT, and BerEP4 could be helpful in distinguishing porocarcinomas from SCCs. In addition, NUTM1 immunoexpression is highly specific, although not sensitive, to porocarcinomas. GATA3 immunohistochemistry has no meaningful implications in the differential diagnosis of porocarcinoma and SCC.

Nuclear ß-catenin immunoexpression in scars.

BACKGROUND: Histopathologically, scars can mimic superficial fibromatoses. Superficial fibromatoses are known to show nuclear ß-catenin immunoexpression, although the tumor types do not harbor CTNNB1 or APC alterations. This study aimed to evaluate nuclear ß-catenin immunoexpression in scars compared to that in superficial fibromatoses. METHODS: Immunostaining with an anti-ß-catenin antibody, clone 14, was performed on 8 superficial fibromatoses and 22 scars. The extent of ß-catenin nuclear staining was classified as negative (<10%), focally positive (10-49%), or diffusely positive (50-100%). ß-catenin staining intensity was semi-quantitatively graded as weak, moderate, or strong. RESULTS: In 21 (95%) scars, nuclear ß-catenin immunoexpression was detected in fibroblasts/myofibroblasts, with mainly diffuse (16/21) and moderate (14/21) to strong (5/21) staining. In contrast, seven (88%) of the eight superficial fibromatoses expressed ß-catenin in the nuclei of the lesional spindle cells, at varying levels of staining intensity. Fibroblasts in normal papillary dermis always showed nuclear ß-catenin expression to varying degrees but those in the reticular dermis did not. CONCLUSIONS: Scars typically exhibit nuclear ß-catenin expression similar to that in superficial fibromatoses. Thus, ß-catenin immunohistochemistry is not suitable for distinguishing superficial fibromatoses from scars.