Clinico-laboratory and histological characteristics in patients with gelatinous transformation of bone marrow

Gelatinous transformation（GT）is morphological change of fat tissue that reflects malnutrition. In bone marrow with GT, gelatinous deposits occupying hematopoietic space result in hypocellularity. Therefore, GT is presumed to be a cause of secondary anaemia. To characterise clinical feature, laboratory data and histology in patients with bone marrow GT, we enrolled 104 patients who were autopsied at Tokushima University Hospital and Tokushima Red Cross Hospital between August 2015 and July 2020. The patients were aged 71.7±11.4 years（69.2% male individuals）. Fifty-eight patients（55.8%）had malignant disease. Bone marrow and liver steatosis and medical records were retrospectively studied. Clinical data and basic blood and urine parameters prior to 3 weeks before death were analysed. Eighteen（17%）patients were assigned to the GT group. In this group, two（11.1%）cases were complicated by bone marrow fibrosis. Immunohistochemically, C-X-C motif chemokine ligand 12（CXCL12）-positive stromal cells were present in the GT marrow area; however, the number of stellate-shaped reticular cells with projections strongly positive for CXCL12 was reduced. Statistically, GT was not associated with malignant disease, liver fibrosis, or steatosis. In the GT group, serum creatinine was significantly lower than that in the non-GT group（median 0.75 mg/dL, IQR 0.61–1.17, p=0.047）. The body mass index and geriatric nutritional risk index were also significantly lower in the GT group（median 18.6, IQR 17.3–19.9, p < 0.001; median 66.8, IQR 61.9–70.6, p=0.002, respectively）. These results suggest that bone marrow GT indicates protein-energy malnutrition with muscle loss, but not with anaemia.