Clinical and pathologic analysis of extramedullary tumors after hematopoietic stem cell transplantation

Clinical and pathologic analyses of 41 extramedullary biopsy/resection specimens of extramedullary tumors (EMTs) after hematopoietic stem cell transplantation (HSCT) were performed. The 41 EMT specimens were from 28 patients, with 11 having more than 1 consecutive EMT in different anatomic locations at different times post-HSCT. The median age at EMT diagnosis was 45 years (range, 17-73 years), and the male/female ratio was 17:11. The most common initial diagnosis was acute myeloid leukemia (21), followed by chronic myeloid leukemia with myeloid blast phase (2), primary myelofibrosis with acute leukemic transformation (1), acute lymphoblastic leukemia (2), mixed lineage T/myeloid leukemia (1), and plasma cell myeloma (1). All initial presentations were limited to bone marrow-only disease. Twenty patients had abnormal chromosomal karyotypes, whereas 6 had normal cytogenetics with their original disease. All patients received standard chemotherapy followed by allogeneic (27) or autologous (1) HSCT. The EMTs occurred 2 to 177 months (median, 16.5 months) after HSCT and were diagnosed as solid mass lesions as follows: skin and soft tissue (10), central nervous system and paraspinal tissue (9), breast (7), gastrointestinal tract (4), lymph node (4), genitourinary system (4), and mediastinum (3). Interestingly, all but 3 patients had negative bone marrows at the time their EMT was diagnosed, indicating that most EMTs presented as sole lesion of relapsed disease. The overall outcome was dismal for patients with EMT, with 20 (71%) of 28 patients deceased at 1 to 26 months after EMT diagnosis, with a median overall survival of only 6.5 months.