Near missed diagnosis of Merkel cell carcinoma in a young immunocompetent woman with a recurrent left-arm mass: A case report.

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine cancer that primarily affects the elderly, Caucasians, and the immunocompromised. We present a rare case of an immunocompetent young Iranian (non-Caucasian) female with a small nodule on her left arm. The lesion was initially misdiagnosed as an infected cyst and was treated with antibiotics for 20 days before being surgically removed. Unfortunately, the lump regrew rapidly 2 weeks later, when she had a biopsy, which revealed stage III MCC. She was then treated with adjuvant chemoradiotherapy after a thorough surgical resection of the tumor. Despite the fact that she was in remission after completing chemotherapy courses, she developed neutropenic fever, sepsis and died from septic shock. This case emphasizes the necessity of early clinical diagnosis of MCC and obtaining a biopsy with histopathologic evaluation of rapidly evolving skin lesions suggestive of malignancy.