[Primary localized cutaneous nodular amyloidosis: A diagnostic and therapeutic challenge]

Background: Nodular primary localized cutaneous amyloidosis (PLCA) is a rare subtype of localized cutaneous amyloidosis in which amyloid protein is derived from immunoglobulin light chains. Follow-up for progression to systemic amyloidosis or autoimmune disease is mandatory. No consensus exists regarding treatment.

Patients and methods: We report a case of nodular PLCA in a 49-year-old man, presenting as an asymptomatic nodule of the nose. Skin biopsy revealed diffuse deposition of amyloid associated with plasmocyte proliferation. Monotypic kappa light-chain restriction was observed. Extensive systemic evaluation, including bone marrow biopsy and PET scan, was negative. Protein electrophoresis and immunofixation in serum and urine were normal. The nodule was treated with radiotherapy but there was no response. Mohs micrographic surgery (MMS) was performed with no recurrence at 6 months of follow-up. No systemic progression was observed one year after the initial diagnosis.

Discussion: Since nodular PLCA may have a cutaneous presentation similar to that of primary systemic amyloidosis, evaluation for systemic amyloidosis is necessary. Treatment of amyloidosis is difficult. Radiotherapy appears ineffective in treating this type of primary cutaneous amyloidosis, and surgical treatment, where possible, is a good option, especially with MMS, which allows both controlled excision and minimal margins.