Primary Hepatic Other Iatrogenic Immunodeficiency-Associated Lymphoproliferative Disorders After Methotrexate Therapy

Prior reports described cases of lymphoproliferative diseases occurring after methotrexate (MTX) administration, which are called methotrexate-associated lymphoproliferative disorders (MTX-LPDs). It has become clear that these lymphoproliferative diseases also occur following treatment with other immunosuppressive drugs, and they have been termed as other iatrogenic immunodeficiency-associated lymphoproliferative disorders (OIIA-LPDs). In most of these cases, the duration of immunosuppressive drugs is very long, on the order of years. In the present study, we evaluated the development of lymphoproliferative disease despite the short duration of immunosuppressive treatment and determined the tumor doubling time. A 71-year-old woman was diagnosed with adult-onset Still's disease. The patient was administered prednisone 30 mg per day starting on February 25, 2022 and MTX 6 mg per week starting 2 weeks later. Because she was a hepatitis B virus (HBV) carrier, nucleic acid analog therapy was also started to prevent HBV activation. Eight weeks later, biweekly tocilizumab was started. After 5 months of MTX administration, a solitary liver tumor measuring 37 × 32 mm² was detected. Three months later, repeat computed tomography revealed that the liver tumor had grown rapidly to 7 cm in diameter. We considered the possibility of OIIA-LPDs and stopped MTX therapy. Biopsy specimens of the liver tumor exhibited lymphocyte proliferation, which was consistent with OIIA-LPDs. The doubling time for tumor growth was 33 days. Despite withdrawing MTX for 6 weeks, the tumor continued to grow, and thus, the patient was referred to the hematology unit. In previously reported cases of MTX-LPDs of hepatic origin, the average duration of MTX administration was 7.3 (2 - 13) years. This report describes a primary hepatic OIIA-LPDs-associated tumor that rapidly increased in size after an extremely short period of MTX administration.