[Tumoral and pilotropic mycosis fongoides without mucin: evolution towards a pustulous erythroderma]. / Mycosis fongoïde tumoral et pilotrope sans mucine: évolution vers une érythrodermie pustuleuse.

INTRODUCTION: Pilotropic mycosis fongoides is a particular form of the disease, because of its clinical and histological aspects, its poor prognosis and its resistance to treatment. We report a case of pilotropic mycosis fongoides without mucinosis, immediately tumoral, the fatal progression of which was marked by the occurrence of pustular erythroderma. OBSERVATION: In 1998 a 69 year-old man presented with infiltrated erythro-squamatous plaques and nodules on the limbs associated with follicular lesions predominating on the cervical-cephalic area. Histological explorations revealed a pilotropic infiltrate with atypical CD4+ CD8 CD30 T-cells, without epidermotrophism or mucinosis. Study of genetic rearrangements found a clone lymphocyte T-cell in the skin. Diagnosis of pilotropic mycosis fongoides at the tumoral stage was made and, despite various treatments, the disease developed towards fatal pustular erythroderma. DISCUSSION: At the onset of its progression, pilotropic mycosis fongoides is sometimes difficult to distinguish from classical mycosis fongoides, during which follicular involvement is often seen. However it is important to differentiate these entities because of the poor prognosis of pilotropic mycosis fongoides. Development of tissue micro dissection techniques and lymphocyte T-cell clones from human skin would help to separate these cutaneous T-cell lymphoma sub-groups. Our case report is original because of the absence of dermal mucinosis combined with an immediately tumoral form and the progression towards generalized pustulosis. It also underlines the poor prognosis and resistance to treatment of pilotropic mycosis fongoides.