Merkel cell carcinoma of the lower extremity: report of four cases and new considerations.

Abstract

Merkel cell carcinoma (MCC) is a rare neuroendocrine cutaneous malignancy that predominantly arises in the head and neck region. We describe clinical features, diagnosis, and treatment in 4 cases of MCC, presenting an uncommon female predominant occurrence and an unusual primary site: the lower limb. In all cases diagnosis was established by histopathologic examination. Primary MCC and locally recurrence disease were treated in all patients with a wide surgical excision (3-cm margin) including fascia. Lymphadenectomy was reserved for a patient with clinical evidence of nodal involvement. Both chemotherapy administered in 2 cases and radiotherapy in 1 case produced limited responses. Early diagnosis is critical because this tumor is aggressive and has a high rate of local recurrence and metastatic spread. However, its nondistinctive appearance frequently delays diagnosis and its rarity avoids an optimal treatment guideline setting.