Melan-A Expression in Poorly Differentiated Carcinoma of Lung: A Potential Diagnostic Pitfall
Abstract BackgroundMelan-A/MART-1 is a melanocytic differentiation marker, which is recognized as an antigen on melanoma cells. It is relevant for pathologists as a useful diagnostic marker in the diagnosis of melanocytic tumors. However, the expressional pattern of Melan-A in poorly differentiated carcinoma of lung has never been reported so far.Case presentationHere, we report a 77-year-old female patient who presented with a large mass in the right lung and was subsequently diagnosed with a poorly differentiated carcinoma of lung. We unexpectedly found that the carcinoma in this patient exhibited diffuse Melan-A expression. ConclusionThis is the first case reported of a poorly differentiated carcinoma of lung with Melan-A expression. This report shows that Melan-A can express in poorly differentiated carcinoma, and highlights a potential diagnostic pitfall in the diagnosis of carcinoma, which urges pathologists to exercise caution in cases where Melan-A positivity and illustrates the need for further immunohistochemical or molecular examination to avoid misdiagnosis.