Cytokeratin positivity in anaplastic large cell lymphoma: a potential diagnostic pitfall in misdiagnosis of metastatic carcinoma

摘要

Cytokeratin (pan) and epithelial membrane antigen (EMA) were considered as commonly useful epithelial markers to distinguish cancer from lymphoma, but the expression of cytokeratin (pan) and EMA had also been seen in some lymphomas. Here, we presented an unusual case of anaplastic large cell lymphoma (ALCL) absence of some lymphoid markers (Including CD3, CD20, Pax-5, CD45Ro) and positive for cytokeratin (pan) and EMA, which was misdiagnosed as metastatic carcinoma. Our case suggested that the epithelial markers (including cytokeratin and EMA) show an overlap with that of ALCL, which represented a diagnostic pitfall for confusing ALCL with metastatic carcinoma.