A 21-year-old man with a history of hemochromatosis and chronic heart failure presented with a 6-month history of weight loss (13.5 kg), fatigue, and generalized weakness. On physical examination, he appeared older than stated age, had cachexia with temporal wasting, and was unable to get up from a sitting position. Laboratory test results were as follows: hemoglobin, 10.7 g/dL; hematocrit, 30.2%; red blood cells, 3.13 × 1012/L; white blood cell count, 2.9 × 109/L; total iron-binding capacity, 190 μg/dL; iron, 75 μg/dL; ferritin, 306 μg/L; alanine aminotransferase, 77 U/L; aspartate aminotransferase, 40 U/L; and alkaline phosphatase, 32 U/L. The peripheral blood smear was unremarkable (not shown). Subsequent bone marrow biopsy showed marked hypocellularity and gelatinous stromal transformation, consistent with advanced serous fat atrophy. The gelatinous substance stained strongly with alcian blue at a pH of 2.5. Serous fat atrophy (gelatinous bone marrow transformation) is a rare condition that presents with weight loss and anemia.1Böhm J Gelatinous transformation of the bone marrow: the spectrum of underlying diseases.Am J Surg Pathol. 2000 Jan; 24: 56-65Crossref PubMed Scopus (112) Google Scholar Although the pathogenesis is unknown, serous fat atrophy has been associated with acute febrile states, AIDS, alcoholism, anorexia nervosa, cachexia, carcinomas, chronic heart failure, and lymphoma.1Böhm J Gelatinous transformation of the bone marrow: the spectrum of underlying diseases.Am J Surg Pathol. 2000 Jan; 24: 56-65Crossref PubMed Scopus (112) Google Scholar, 2Delacrétaz F Perey L Schmidt PM Chave JP Costa J Histopathology of bone marrow in human immunodeficiency virus infection.Virchows Arch A Pathol Anat HistoPathol. 1987; 411: 543-551Crossref PubMed Scopus (58) Google Scholar, 3Tavassoli M Eastlund DT Yam LT Neiman RS Finkel H Gelatinous transformation of bone marrow in prolonged self-induced starvation.Scand J Haematol. 1976; 16: 311-319Crossref PubMed Scopus (79) Google Scholar Serous fat atrophy has an adult male predominance, with maximal severity in men aged 20 to 29 years.1Böhm J Gelatinous transformation of the bone marrow: the spectrum of underlying diseases.Am J Surg Pathol. 2000 Jan; 24: 56-65Crossref PubMed Scopus (112) Google Scholar Bone marrow changes are characterized by fat cell atrophy, focal to diffuse loss of hematopoietic cells, and deposition of extracellular mucopolysaccharides rich in hyaluronic acid, without reticulin fibers.1Böhm J Gelatinous transformation of the bone marrow: the spectrum of underlying diseases.Am J Surg Pathol. 2000 Jan; 24: 56-65Crossref PubMed Scopus (112) Google Scholar, 4Seaman JP Kjeldsberg CR Linker A Gelatinous transformation of the bone marrow.Hum Pathol. 1978; 9: 685-692Abstract Full Text PDF PubMed Scopus (88) Google Scholar The mucopolysaccharide gelatinous material is confirmed by strong alcian blue staining at a pH of 2.5.5Clarke BE Brown DJ Xipell JM Gelatinous transformation of the bone marrow.Pathology. 1983; 15: 85-88Crossref PubMed Scopus (19) Google Scholar The bone marrow changes can be reversed by treating the associated condition.3Tavassoli M Eastlund DT Yam LT Neiman RS Finkel H Gelatinous transformation of bone marrow in prolonged self-induced starvation.Scand J Haematol. 1976; 16: 311-319Crossref PubMed Scopus (79) Google Scholar