Common Diseases Presenting in an Uncommon Way: Metastatic Small-Cell Lung Carcinoma Mimicking Merkel Cell Carcinoma

Division

West Florida

Hospital

Doctors Hospital of Sarasota

Document Type

Case Report

Publication Date

5-28-2025

Keywords

merkel cell cancer, metastatic basal cell carcinoma, monoclonal antibody therapy, rare cancers, small-cell lung carcinoma

Disciplines

Internal Medicine | Medicine and Health Sciences | Neoplasms | Respiratory Tract Diseases

Abstract

A 65-year-old Caucasian woman presented with a rapidly enlarging, painless forehead lesion initially presumed to be Merkel cell carcinoma (MCC). Originating as a 3 mm pink papule, the lesion expanded to over 12 mm within six months. Subsequent histopathologic and radiologic evaluation revealed it to be the initial manifestation of metastatic small-cell lung carcinoma (SCLC). Despite undergoing surgical resection under the presumption of localized MCC, advanced imaging later identified a primary pulmonary neoplasm with diffuse metastatic spread. Histologically, both MCC and SCLC are characterized by poorly differentiated neuroendocrine morphology, complicating clinical distinction. Cutaneous metastases from SCLC, although rare, can deceptively mimic primary neuroendocrine skin neoplasms, as exemplified in this case. This diagnostic pitfall underscores the imperative for comprehensive staging prior to initiating definitive therapy, as incomplete evaluation may precipitate unnecessary surgical intervention and delay optimal systemic treatment.

Publisher or Conference

Cureus

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