An Ulcerative Cutaneous Plasmacytosis of the Scalp

Introduction: Cutaneous plasmacytosis (CP) is a rare benign disorder characterized by polyclonal proliferation of plasma cells of unknown etiology, with potential for malignant transformation. Clinical manifestations include reddish-brown macules, papules, plaques, or nodules, and, infrequently, ulcerative lesions resembling cutaneous squamous cell carcinoma (SCC) or similar cutaneous neoplasms. Case: Herein we reported a case of ulcerative CP which was initially suspected as SCC in a 77–year–old male. Physical examination revealed an ulcer with well–defined borders, and flat edges, with a granulation tissue base on the scalp which was suggested as SCC. Histopathological features showed infiltration of mature plasma cells in the perivascular area, polyclonal plasma cell population on kappa and lambda chain immunohistochemistry, and hypergammaglobulinemia on protein electrophoresis that supported the diagnosis of CP. Discussion: Cutaneous plasmacytosis requires a comprehensive diagnostic evaluation, which typically includes clinical examination, histopathological analysis, immunohistochemistry, ancillary tests such as protein electrophoresis, and negative results from a diagnostic workup for systemic disease. Conclusion: The complexity of CP manifestations necessitates a rigorous diagnostic approach, enabling the differentiation of this benign condition from malignancies with similar presentations.