Cutaneous Metastasis As the Initial Clue to Lung Adenocarcinoma: A Case Report.

Cutaneous metastasis is an uncommon but clinically significant manifestation of internal malignancy, often indicating advanced disease and poor prognosis. Its varied clinical morphology often mimics benign dermatological conditions, posing a diagnostic difficulty. In certain cases, cutaneous metastasis can be the sentinel sign of an undetected primary tumor. We report the case of a 65-year-old woman with a prior history of treated cervical carcinoma who presented with a new-onset skin lesion over her shoulder. Subsequent histopathological, immunohistochemical, and radiological evaluations confirmed cutaneous metastasis arising from a new primary lung adenocarcinoma rather than recurrence of the cervical carcinoma. This case highlights the importance of meticulous histopathological and immunohistochemical evaluation in patients with a history of malignancy presenting with a new, atypical cutaneous lesion. Even after a prolonged disease-free interval, such lesions may represent secondary metastasis from a distinct primary malignancy rather than recurrence of the original tumor. Early recognition of cutaneous metastasis provides an important diagnostic clue to an underlying primary malignancy and facilitates timely management.