Two cases of Hodgkin’s lymphoma presenting subsequent to methotrexate treatment for rheumatoid arthritis

Background : It is known that methotrexate (MTX) used for the treatment of rheumatoid arthritis (RA) can cause malignant lymphoma. We report here two cases of classical Hodgkin’s lymphoma (CHL) that presented following RA treatment using MTX. Case : Case 1 was a 50-year-old female, who underwent a biopsy after a swollen right axillary lymph node was discovered following MTX treatment over a 6-year period. Case 2 was a 60-year-old male who presented with Pneumocystis carinii pneumonia after MTX treatment for 1 year, followed by swollen lymph nodes in the right inguinal region and left cervical region, prompting us to biopsy the left cervical lymph nodes. In both of these cases, we sporadically observed large Hodgkin and Reed-Sternberg (HRS) cells in conspicuous nucleoli among small lymphocytes and histiocytes using imprint cytology. Although HRS cells were also found histologically, when examined immunohistologically, in case 1 they tested positive for CD30 and CD15 and negative for CD20, while in case 2, they tested positive for CD30 and CD79a, weakly positive for a portion of CD20 cells and negative for CD15. Conclusion : Cytologically, typical CHL images were observed, and based on the clinical course of these two cases, we believe that they correspond to MTX-associated lymphoproliferative disorders (LPDs), classified by WHO as a subtype of immune deficiency associated with LPDs. Furthermore, while case 1 had normal immunohistological CHL patterns, we thought it prudent to assess case 2 as Hodgkin-like LPD. For many of these types of cases, it is difficult to follow the complex clinical course, and we believe it necessary to base a comprehensive diagnosis on a full understanding of the underlying disorder.