Reversible cutaneous lymphoma occurring during methotrexate therapy

A B-cell lymphoma, restricted to the skin, developed in a 58-year-old man receiving methotrexate for non-rheumatoid peripheral arthritis, with the simultaneous occurrence of a cytolytic hepatitis and carcinoma of the lung. Two weeks after methotrexate was stopped, both the skin tumour and the hepatitis disappeared spontaneously, with no recurrence during a 12-month follow-up period. Immunoglobulin gene rearrangement was shown by polymerase chain reaction (PCR) but in situ hybridization failed to reveal neoplastic cells positive for Epstein-Barr virus (EBV).