Lichenoid mycosis fungoides: Report of a case with lichen planus-like histopathologic features.

Key Clinical Message: Mycosis fungoides is a diagnostic challenge. Herein, we report a case with marked lichenoid features in pathology assessments. After several biopsies and clinicopathologic correlation, the diagnosis of lichenoid mycosis fungoides was made.

Abstract: Mycosis fungoides (MF) is a great imitator and mimicks other dermatoses clinically and histopathologically. We report a 61-year-old patient with 5-year history of generalized violaceous patches and plaques. His biopsy revealed a marked lichenoid band-like infiltrate of inflammatory cells along the basal layer with basal layer vacuolar changes; the diagnosis of lichen planus was first made histopathologically. Several biopsy specimens, clinicopathologic correlation, and immunohistochemistry findings confirmed the diagnosis of lichenoid MF. Awareness of peculiar histopathologic findings of MF is essential to avoid a potential misdiagnosis. When in doubt, multiple biopsies with other diagnostic methods should be employed.