SEA-BLUE HISTIOCYTOSIS: A NEWLY REPORTED COMPLICATION OF PARENTERAL NUTRITION. S. Frost 1 ; 1 Cleveland Clinic Foundation, Cleveland, OH (Tracking ID #73897) LEARNING OBJECTIVES: 1) Diagnose sea-blue histiocytosis syndrome as a complication of total parenteral nutrition (TPN). 2) Recognize that bone marrow sea-blue histiocytes are associated with many diseases in which the degradation of lipids and cellular lipid products is exaggerated. CASE INFORMATION: A 40 year-old man receiving chronic TPN with lipid emulsion after esophagogastrectomy following caustic ingestion was admitted to the hospital with fever for 5 days, jaundice, hepatitis, and pancytopenia. The patient did not appear ill. The physical exam was notable for a clean subclavian Hickman catheter site without erythema or tenderness, hepatomegaly, no heart murmur, and no peripheral stigmata of endocarditis. Laboratory revealed WBC = 3.8 K/uL, hemoglobin = 10 g/dL, platelet = 70 K/uL, AST = 223 U/L, ALT=160 U/L, alkaline phosphatase = 339 U/L, and bilirubin = 9.4mg/dL. Investigation for bacterial, fungal, mycobacterial, and viral infection was negative. Abdominal sonogram and CT scan revealed hepatomegaly without other abnormality. Echocardiogram revealed no vegetations. Upper extremity ultrasound was negative for catheter associated thrombosis. The Hickman catheter was removed and catheter culture specimens were sterile. Fever persisted despite therapy with piperacillin/tazobactam, vancomycin, fluconazole, and amphotericin B. Bone marrow biopsy revealed sea-blue histiocytes. TPN was held and improvement in liver function abnormalities and cell counts began on hospital day (HD) 6 and 7 respectively. Fever dissipated on HD 8, and antimicrobials were discontinued. TPN was restarted without lipid emulsion, and the patient has remained well with resolution of hepatitis and cytopenias. IMPLICATIONS/DISCUSSION: Sea-blue histiocytes (SBHs) are macrophages with lysosomal lipid accumulations that appear blue with Giesma staining. The sea blue histiocytosis syndrome is a typically benign idiopathic disorder characterized by hepatosplenomegaly, purpura, thrombocytopenia, and pulmonary infiltrates. SBHs have also been noted in association with hematologic disorders such as chronic myeloid leukemia, and metabolic illnesses such as Niemann Pick disease. SBHs in the bone marrow of patients with hepatosplenomegaly, jaundice, and pancytopenia receiving TPN containing lipid emulsions was first reported in 1996. Lowering the TPN lipid content has been shown to improve pancytopenia. Lipid induced hematopoetic cell membrane alterations triggering macrophage phagocytosis is one postulated mechanism accounting for TPN related sea-blue histiocytosis (TPN-SBH). This patient's illness is consistent with prior descriptions of TPN-SBH, except for fever, which has not been previously reported. However, the resolution of fever coincident with the improvement in pancytopenia and hepatitis after the discontinuation of parenteral lipids suggests an association with TPN-SBH.