Juvenile folliculotropic and ichthyosiform mycosis fungoides.

Ichthyosiform mycosis fungoides (MF) is a recently recognized clinical variant of MF, which appears as dry scaling patches and plaques, or as a generalized eruption. Acquired ichthyosis is well recognized as a paraneoplastic cutaneous presentation of malignancy, especially in lymphoproliferative disorders. In contrast, the ichthyosiform eruption in ichthyotic MF is attributable to infiltration of the skin by tumour cells. We report the case of a 15-year-old boy who presented with a 5-year history of enlarging pruritic plaques on the forehead and back, patchy alopecia and generalized ichthyosis. Histology of the forehead and back showed a dense, lymphocytic, folliculocentric and perivascular infiltrate of predominantly CD4-positive T cells consistent with folliculotropic MF. Histological examination of biopsies from ichthyotic skin found similar features. Our patient had a histological diagnosis at the age of 15 years, making him the youngest reported patient with either folliculotropic MF or ichthyotic MF.