Serous atrophy of bone marrow manifested as subcutaneous and visceral fat depletion on CT: two case reports

Serous atrophy of the bone marrow (SABM) is primarily caused by the breakdown of bone marrow fat due to the depletion of body fat reserves. SABM is linked to poor nutritional status or cachexia in advanced cancer stages and exhibits distinct characteristics on magnetic resonance imaging (MRI). However, these adverse conditions create challenges for undergoing MRI, thereby delaying timely diagnosis. This case report details changes in body fat tissue observed through CT scans during the progression of two SABM cases. Two patients were elderly males, and both had undergone chemotherapy and immunotherapy following gastric cancer resection. The MRI scans of both patients revealed the characteristic "flip-flop" effect, in which T1WI appears to show fat suppression, while fat-suppressed T2WI appears to show fat without suppression. This finding differs from other bone marrow disorders and led to a diagnosis of SABM. Previous longitudinal CT analyses indicated that both subcutaneous and visceral fat tissues were not only reduced but had ultimately disappeared, resulting in a fluid-like density in the CT images of two cases. This finding indicates the depletion of body fat reserves. Furthermore, it suggests a significant deterioration in nutritional status and raises strong suspicion regarding the potential development of SABM.