Gelatinous transformation and concomitant fibrosis of bone marrow in a patient with relapsed myelodysplastic syndrome following unrelated bone marrow transplantation.

Gelatinous transformation of bone marrow (GTBM) is a rare histological condition characterized by deposition of hyaluronic acid-rich gelatinous material, usually accompanied by adipocyte atrophy, reduced reticulin fibers, and hypocellularity. Although most frequently associated with malnutrition and severe weight loss, GTBM has also been reported in hematological malignancies. The coexistence of GTBM and bone marrow fibrosis is rarely described, and its underlying mechanisms remain unclear. We report a 69-year-old woman with myelodysplastic syndrome with excess blasts-1 (MDS-EB-1) harboring a complex karyotype including chromosome 7 abnormalities, classified as very high risk by IPSS-R. She underwent unrelated bone marrow transplantation and achieved complete remission. On day 35, she developed acute skin graft-versus-host disease (GVHD), which resolved with immunosuppressive therapy. Five months later, she presented with pancytopenia, chronic cutaneous GVHD, severe anorexia, 15-kg weight loss, and malnutrition (BMI 11.5 kg/m2). Bone marrow aspiration yielded a dry tap, while biopsy revealed Alcian blue-positive gelatinous material, reticulin fibrosis, and preserved adipocytes. Her disease progressed to acute myeloid leukemia with 50% circulating blasts and was refractory to azacitidine and CPX-351, leading to death from progression. This case illustrates that GTBM and marrow fibrosis can occur simultaneously in relapsed MDS after transplantation, potentially driven by cytokine dysregulation related to neoplastic clones and chronic GVHD.