Folliculotropic mycosis fungoides with central nervous system involvement: Demonstration of tumor clonality in intrafollicular T cells using laser capture microdissection

Background: Folliculotropic mycosis fungoides (MF) is a rare variant of cutaneous T-cell lymphoma, MF type, characterized by atypical lymphocytes preferentially infiltrating the hair-follicle epithelium relative to the epidermis. Observations: We describe a rare case of folliculotropic MF involving the central nervous system. This is also the first case in which laser capture microdissection was used to show that the atypical lymphocytes within the hair-follicle epithelium were part of the same tumor clone present in other tissue compartments. Conclusions: In reviewing the literature describing atypical lymphocytes infiltrating hair-follicle epithelium relative to the epidermis, we encourage the use of the term folliculotropic mycosis fungoides. Our case also supports previous findings that central nervous system involvement can occur in advanced MF. The successful procurement and analysis of atypical lymphocytes from hair-follicle epithelium by laser capture microscopy ushers in a new era in molecular diagnostics.