Sodium valproate-induced cutaneous pseudolymphoma followed by recurrence with carbamazepine

We report a patient with a sodium valproate-induced cutaneous pseudolymphom a, presenting with an erythematous papule, histologically mimicking a non-e pidermotropic T-cell lymphoma. Polymerase chain reaction study of the skin biopsy revealed monoclonal rearrangement of the T-cell receptor gamma gene. Withdrawal of sodium valproate was followed by regression of the lesion, b ut 5 months after substitution by carbamazepine, two further papules appear ed, with similar histological features and a T-cell clone identical to the initial one. Carbamazepine was stopped and the lesions disappeared without relapse over a 4-year follow-up. Sodium valproate is very rarely responsibl e for a hypersensitivity syndrome, and our case is the first report of sodi um valproate-induced cutaneous pseudolymphoma. The recurrence with carbamaz epine may be due to a common effect on T-cell lymphocyte function. The retu rn of the same monoclonal population shows that the recurrence of monoclona l T cells may be observed in benign conditions and is not an exclusive hall mark of cutaneous lymphoma.