Melanocytic marker Melan-A detects molluscum contagiosum bodies.

Melan-A is one of the most commonly used immunohistochemical assays (IHC) in dermatopathology laboratories to detect the presence and outline the distribution of melanocytes. It is a cytoplasmic stain that detects a melanocyte-specific cytoplasmic protein involved in the formation of stage II melanosomes. Clinically, Melan-A is primarily used to detect and confirm melanocytic tumors although it is also positively expressed in adrenal cortical tumors and sex cord stromal tumors. We found that Melan-A also detected and highlighted Henderson-Patterson bodies of molluscum poxvirus. To determine if other melanocytic markers detect molluscum contagiosum bodies, S-100, HMB-45, MITF, and SOX-10 were also tested. In 15 tested molluscum cases, Melan-A stains were positive in all cases, whereas the other tested melanocytic markers were negative. Our results confirm that Melan-A is very sensitive in detecting molluscum contagiosum bodies and could be clinically useful to supplement the hematoxylin and eosin (H&E) in cases that are very inflamed or only have limited biopsy material.