Langerhans Cell Sarcoma: A Case Report Demonstrating Morphological and Immunophenotypical Variability within a Single Lesion.

Langerhans cells are antigen presenting dendritic cells and tumours arising from these are rare. The tumours arising from these dendritic cells are divided into two categories according to a WHO classification: Langerhans cell histiocytosis and Langerhans cell sarcoma. It is the degree of atypia and clinical aggressiveness that distinguishes the two subtypes. Langerhans cell sarcoma (LCS) is a neoplastic proliferation of Langerhans cells which can occur in skin, bone marrow, lymph nodes, spleen, liver, and lung. LCS can present with multiple cutaneous and systemic lesions. We present a case of Langerhans cell sarcoma with a unique morphological appearance and variable immunohistochemical profile within a single cutaneous lesion. LCS is a rare malignancy and its diagnosis is based on morphology, immunophenotypical examination, and ultrastructural analysis by electron microscopy. Our case highlights a unique morphological description of LCS wherein the pleomorphic neoplastic cells show epidermotropism and are surrounded by a variable amount of inflammatory infiltrate within a single cutaneous lesion. A single cutaneous lesion of Langerhans cell sarcoma with variable immunohistochemical profile has not been described so far.