Primary or metastatic lung cancer? Sebaceous carcinoma of the thigh: A case report.

Background: Sebaceous carcinoma (SC), a malignancy primarily characterized by aggressive growth, affects cutaneous tissues of the periocular region. Extraocular SC is extremely rare, especially in the extremities, as evidenced by only a handful of reported cases.

Case Summary: A 65-year-old man presented with a rapidly enlarging swelling on the left inner thigh, which was initially misdiagnosed as a subcutaneous abscess. The lesion had appeared two months prior to admission. Clinical examination revealed a cauliflower-like swollen content, with an ulcerated and infected mass located on his left thigh. At the same time, we observed solitary nodular lesions in his lungs and brain, with biopsy pathology of the lung lesions found to be consistent with the mass in the thigh. The patient received chemotherapy comprising cis-platinum with fluorouracil, followed by targeted therapy with anlotinib hydrochloride and chemotherapy with vinorelbine, implantation of iodine-125 seeds in the thigh and pulmonary tumor. The initial stage intervention achieved partial remission. The efficacy of maintenance treatment was evaluated as stable disease after the first 5 cycles; however, the patient developed a new brain lesion after the sixth cycle of treatment, which resulted in progressive disease and he received whole brain gamma knife radiotherapy.

Conclusion: We analyzed the clinical presentation, imaging features, pathology and treatment of a rare case of lung, brain and lymph node metastasis of SC located in the thigh. It is evident that cis-platinum combined with fluorouracil, vinorelbine combined with anlotinib hydrochloride may be an effective therapeutic regimen in advanced SC. However, brain metastatic lesions should receive early radiotherapy.