Patients receiving phenytoin may develop pseudolymphoma or, rarely, malignant lymphoma and mycosis-fungoides-like lesions. Lymphoid hyperplasia can be localized in the cervical area. Enlargement of inguinal lymph nodes during chronic phenytoin therapy has been reported.
Most patients present with a single, slowly enlarging, papular, nodular, or plaquelike lesion several weeks following the initiation of anticonvulsant medications. However, several patients have demonstrated drug-induced pseudolymphoma after more than 5 years of therapy.
Immunophenotyping of the lymphoma is essential to make the daignosis. Most drug-induced pseudolymphomas contain CD3+CD4+ T cells
Other physical findings may include splenomegaly, marked localized or diffuse lymphadenopathy, and high-grade fever.