Multiple skin and subcutaneous metastasis as initial manifestation in neuroendocrine carcinoma lung: A rare case report.

Pulmonary neuroendocrine tumors are uncommon malignancies, and cutaneous metastasis as the initial presentation is exceedingly rare, often leading to diagnostic delays due to nonspecific clinical features. We reported a case of a 57-year-old male presenting with multiple progressively enlarging, painless cutaneous and subcutaneous nodules on the scalp and left chin without accompanying respiratory and constitutional symptoms. The lesions were initially treated as benign dermatological conditions without improvement. Excisional biopsy of a chin lesion demonstrated dermal infiltration by atypical polygonal cells with neuroendocrine morphology and dermal lymphatic invasion. Immunohistochemistry showed positivity for synaptophysin, cytokeratin 7 (CK7), and Cam5.2, consistent with neuroendocrine carcinoma. Contrast-enhanced computed tomography identified a heterogeneously enhancing mass in the left lower lobe of the lung with widespread metastatic disease. Further evaluation with Gallium-68 DOTATATE positron emission tomography/computed tomography, a somatostatin receptor-targeted imaging study, demonstrated avid lesions in the lung, lymph nodes, subcutaneous tissue, omentum, and skeleton. The patient was treated initially with octreotide hormone therapy. The patient had disease progression; therefore, therapy was changed to carboplatin and etoposide. This case highlights that unexplained skin lesions may present as the initial manifestation of an underlying visceral malignancy, signifying the role of early biopsy and comprehensive imaging to enable timely diagnosis and management of aggressive pulmonary neuroendocrine tumors.