An unusual case of mycosis fungoides presenting as sarcoidosis or granulomatous mycosis fungoides.

The authors describe a case of cutaneous and lymph node granulomas first reported as sarcoidosis. As skin sarcoidlike reactions disappeared, the development of typical histologic and immunopathologic features of cutaneous mycosis fungoides suggested granulomatous mycosis fungoides. This case illustrates the difficulties in differentiating true systemic sarcoidosis associated with mycosis fungoides from sarcoidlike reactions when extensive granulomas obscure the underlying cutaneous lymphoma. This report emphasizes the utility of immunohistochemical analysis to identify the early cutaneous T-lymphomatous infiltrate, initially admixed with epithelioid and giant cell granulomas. This technique also made it possible to characterize a Ki-1-positive anaplastic large-cell lymphoma when the transformation of mycosis fungoides into highly malignant lymphoma occurred in the lymph node.