Merkel cell carcinoma- particularities and morphological aspect of a unique and rare entity case report

Andreea Cătălina Tinca; Bianca Andreea Lazar; Ovidiu Simion Cotoi

doi:10.2478/amma-2024-0008

Andreea Cătălina Tinca Department of Pathophysiology, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, Romania Pathology Department, Mures Clinical County Hospital, 540011 Targu Mures, Romania
Bianca Andreea Lazar Pathology Department, Mures Clinical County Hospital, 540011 Targu Mures, Romania
Ovidiu Simion Cotoi Department of Pathophysiology, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, Romania Pathology Department, Mures Clinical County Hospital, 540011 Targu Mures, Romania

DOI: https://doi.org/10.2478/amma-2024-0008

Keywords: Merkel Cell Carcinoma, immunohistochemistry, rare neoplasm, malignant

Abstract

Introduction

Merkel cell carcinoma is a very rare malignant neoplasm which presents high aggressivity, high recurrence rate and has metastatic potential. Our purpose is to present the histological and immunohistochemical particularities of Merkel Cell Carcinoma while reviewing potential differential diagnoses and challenges that we can encounter in daily practice.

Methods

We report the case of a 86 years old female patient who presented with a nodular tumour located in the left forearm.

Results.

The histological appearance of this unique type of cancer is highlighted on the Haematoxylin-eosin stain as a solid tumour composed of nests and chords of monomorphic cells. The nuclei of these tumoral cells appear characteristically as enlarged with dispersed chromatin. The tumoral cells showed positivity for synaptophysin, CD56, NSE, EMA and “dot-like” expression for CK20.

Conclusions.

Sometimes, differentiating this tumour from other primary malignant neoplasms of the skin or even cutaneous metastases can be difficult. Immunohistochemistry remains the most important tool of diagnosis, especially for differentiating this neoplasm from metastatic neuroendocrine tumors that can affect the skin.