RESUMO
Cutaneous involvement is an uncommonly encountered manifestation in multiple myeloma (MM), more commonly observed in patients with aggressive subtypes, and often resistant to conventional therapies. Due to its infrequency, reported clinical characteristics have been diverse and relatively non-specific. Particularly uncommon is lower extremity involvement. In this case report, we present a unique case of a patient with refractory immunoglobulin G lambda MM, who subsequently developed recurrence in the lower leg, while being on systemic therapy. Initially, the lesion resembled squamous cell carcinoma, posing a diagnostic challenge. Through meticulous histopathological and immunohistochemical evaluation, cutaneous involvement by MM was confirmed. This case highlights the importance of maintaining a high clinical suspicion for cutaneous involvement in patients with MM who present with new skin lesions, as early diagnosis is crucial for appropriate management.