Jessner-Kanof lymphocytic infiltration of the skin associated with glatiramer acetate.

Glatiramer acetate (GLAT) is a well tolerated and safe immunomodulatory drug for the treatment of relapsing-remitting multiple sclerosis. The most commonly recognized side effects are localized injection site reactions consisting of pain, pruritus, mild erythema and induration, which sometimes persist for several days. We describe the first case of a biopsy-proven lymphocytic infiltration (T-cell pseudolymphoma) with the clinical appearance of a figured erythema on the ventrolateral thighs in the first four weeks under GLAT treatment, resolving without any evidence of recurrence despite ongoing therapy. A T-cell pseudolymphoma is a very rare side effect of GLAT treatment. For clinical purposes it is important to state that re-exposition after GLAT-induced pseudolymphoma is possible without permanent sequelae.