Abstract

Background: Cutaneous metastases are an uncommon manifestation of internal malignancy and typically indicate advanced systemic disease. Lung cancer is among the most common primary sources of cutaneous metastases in men; however, cutaneous spread from pulmonary squamous cell carcinoma (SCC) occurs less frequently than from adenocarcinoma. Histopathologic evaluation with immunohistochemical (IHC) staining is essential for establishing the diagnosis and identifying the primary tumor source. Case presentation: A 68-year-old male with biopsy-proven stage IV pulmonary SCC and radiographically identified brain and liver metastases presented with a progressively enlarging, friable lesion on the left lateral chin that had been present for four months. The lesion was painless but bled regularly. Physical examination demonstrated a 1.7-cm pink, firm, and exophytic nodule. Punch biopsy revealed metastatic carcinoma consistent with cutaneous metastasis from pulmonary SCC. IHC staining of both the primary lung tumor and the cutaneous lesion demonstrated an identical profile: CK7 positive, p40 positive, and TTF-1 negative. The patient subsequently underwent surgical excision of the lesion with negative margins on final pathology. Discussion: Cutaneous metastases from lung SCC are rare and generally signify disseminated disease with a poor prognosis. Clinical presentation often includes rapidly enlarging dermal or subcutaneous nodules that may mimic benign or primary cutaneous lesions. In this case, biopsy and IHC analysis were critical in confirming the metastatic nature of the lesion and establishing its pulmonary origin. The matching immunophenotype between the primary and metastatic lesions supported the diagnosis of cutaneous spread from lung SCC. Conclusion: This case highlights the importance of maintaining suspicion for cutaneous metastasis in patients with known lung malignancies who develop new or enlarging skin lesions. Skin biopsy with IHC staining provides a reliable method for confirming the diagnosis and identifying the primary tumor source. Recognition of cutaneous metastases is clinically significant because it reflects advanced disease and carries important prognostic implications.

Keywords

squamous cell carcinoma, cutaneous lesions, skin biopsy, dermatology, surgical excision