Phenytoin-Induced Lymphadenopathy

Various lymph node abnormalities have been associated with phenytoin therapy. Four distinct categories of lymphadenopathy have been described: lymphoid hyperplasia, pseudolymphoma, pseudo-pseudolymphoma, and lymphoma. These presentations vary from a benign symptom complex, with enlarged lymph nodes, that is reversible upon drug discontinuance to a true malignant lymphoma that is progressive and ultimately fatal. Benign lymph node hyperplasia and pseudolymphoma may result in erroneous diagnosis and treatment of malignant lymphoma if phenytoin-associated lymphadenopathy has not been considered. We describe a patient who developed enlarged inguinal lymph nodes while receiving chronic phenytoin therapy. An initial diagnosis of malignant lymphoma was made, and recurrent hospitalizations and treatment with cytotoxic drugs ensued. Repeat biopsy, as well as reexamination of the removed nodes, later revealed phenytoin-associated hyperplasia. Patients who develop enlarged lymph nodes while receiving phenytoin should be evaluated carefully so that phenytoin-induced lymphadenopathy may be differentiated from true malignant lymphoma and appropriate treatment may be given.