CD4/CD8 double-negative mycosis fungoides with large cell transformation and involvement of the lungs and leptomeninges

Mycosis fungoides (MF), the most common cutaneous T-cell lymphoma, classically has an indolent clinical course, with lesions slowly progressing from patch to plaque to tumor stage. In some cases, the late stages of disease involve extracutaneous dissemination to lymph nodes or viscera. Although this "Alibert-Bazin" type is the prototypic MF, there are several variants and subtypes of MF that may have different clinical implications for treatment and prognosis. We describe a woman whose disease course involved a variety of histopathologic and immunophenotypic variants including folliculotropic MF, granulomatous MF with loss of CD8, and then finally CD4/CD8 double-negative MF with large cell transformation and extra-cutaneous dissemination. Clinically her disease behaved as classic indolent stage lA MF for nearly two decades before transitioning to tumor stage and then, finally, involving the lungs and leptomeninges. It is important for physicians to be aware of the clinically relevant variants of MF as well as the possibility of transformation of previously stable disease both clinically and histopathologically.