Merkel Cell Carcinoma With Divergent Differentiation-Or Something Else? A Triphasic Cutaneous Carcinoma With Lineage Plasticity.
Zeinab Khalil, Hozaifa Elameen, Ahmed K Alomari
✦ AI-curated · Sources linked
Case in brief
A patient presented with a triphenotypic carcinoma on the left upper arm, characterized by a neuroendocrine carcinoma with Merkel cell features, a poorly differentiated carcinoma with squamous/ductal differentiation, and a sarcomatoid component. Each component exhibited distinct morphologic and immunophenotypic profiles. The case emphasizes the complexity of classification and the need for thorough histologic evaluation and multidisciplinary management.
What made this case unusual
The case features a triphasic carcinoma with three distinct malignant phenotypes, which is exceptionally rare and poses significant diagnostic challenges.
Diagnostic / clinical pearl
Clinicians should be aware of the potential for lineage plasticity in cutaneous carcinomas, necessitating comprehensive histologic and immunohistochemical evaluation.
Why it matters
This case underscores the importance of recognizing complex tumor presentations, which can impact diagnosis, staging, and treatment strategies.