[Mycosis fungoides bullosa: A rare clinical presentation]

Mycosis fungoides (MF) is the most common form of cutaneous lymphoma and usually manifests as erythematous and scaly patches or plaques. Its phenotypic or histologic presentation can be heterogeneous. Herein we report a very rare form of MF bullosa.

A 73-year-old man presented with a 4-month history of erythematous, scaly and itchy plaques on the trunk, as well as blistering lesions present for 2 months and which appeared on the trunk and lower limbs, both on patches of MF and on apparently healthy skin. Histopathology confirmed the diagnosis of bullous mycosis fungoides. Gene rearrangement of TCR showed a monoclonal profile in the skin. The hypothesis of bullous pemphigoid was ruled out by additional exams. Our patient was successively treated with combined interferon, bexarotene and methotrexate, followed by vorinostat, resulting in partial remission.

Cases of bullous MF are very rare. In the literature, the clinical presentation is heterogeneous, with tense or flaccid bullae that can occur on unaffected skin or on erythematous plaques. The bullae generally appear after the plaques. The histologic blister site may be subepidermal or, more rarely, intra-epidermal. The exact mechanism of blister formation is not clear. Its treatment is poorly codified but follows the usual treatment of MF in its classical form.

Bullous MF is a very rare entity that can mimic autoimmune blistering disease, and this diagnosis must therefore be ruled out.