Introduction: Our patient is a 59-year-old female with history of ulcerative colitis who was on chronic steroids and Azathioprine therapy who recently was admitted a month prior for ulcerative colitis flare up, subsequently developed a left MCA stroke and an NSTEMI during her hospital course. She presents to the hospital now with confusion, fever, abdominal pain and shortness of breath. She was apparently feeling well after her discharge up until a week prior to presentation when she developed severe abdominal pain located in bilateral upper quadrants, non-radiating, associated with nausea, vomiting and shortness of breath. She had fevers with Tmax of 102F recorded at home. She also experienced chills, and myalgias, and presented to the hospital when her symptoms took a turn for the worse. Social history included no smoking history, occasional if any alcohol intake, and no history of drug abuse. On initial examination, Temperature was 103.6 F; hypotensive with BP 80/60; tachypneic but normal O2 saturations; on general exam, patient was a pleasant elderly Caucasian female who clinically appeared good, in no acute distress. She has mild expressive aphasia from her previous stroke. Heart and Lung exam was normal. Abdomen exam showed tender hepatomegaly, moderate splenomegaly with spleen size of 18cm. Skin exam showed multiple petechiae in a diffuse distribution. Lab work was significant for pancytopenia; with WBC count of 3000, Anemia with Hemoglobin of 8 (baseline 11), Platelet count of 19000. Chemistry significant for anion gap metabolic acidosis, AST in 9000s, and ALT in 3000 range, Bilirubin around 1.4; ALP of 297, Amylase in 400s, with normal lipase. Ferritin level was as high as 75,500. She underwent an extensive workup including a CT scan of the abdomen and pelvis, which revealed a cystic lesion in the spleen measuring 11.2 x 8.4 x 10 cm. Upon review of previous imaging from previous hospitalizations, there is retrospectively identification of an infarct in the spleen on a CTA of the chest that was performed a month prior to this scan suggesting that the current cystic lesion could represent an irregular or enlarging areas of necrosis or infection. They also identified a splenic artery aneurysm measuring 1.4 cm and a partial thrombus in the splenic artery. The patient underwent IR drainage of the cystic lesion, in which 140 mL of cloudy sanguineous fluid was drained. Preliminary gram stain shows no bacteria and there were many neutrophils present. Final cultures did not isolate any microorganisms. Doppler USG of hepatobiliary vasculature was done which showed multiple sites of obstruction in hepatic sinusoids. There was concern for Paroxysmal Nocturnal Hemoglobinuria/Budd-Chiari syndrome, but investigations were negative. A comprehensive workup was done for identifying rare infectious etiologies for this presentation. Hepatitis, HIV, EBV, Adenovirus, all of which were negative. Our patient met 5 of the diagnostic criteria for HLH and hence a diagnosis was made but very rarely has it been found to be associated with sinusoidal obstruction, and there are no prior reported cases of splenic artery thrombus or aneurysm with HLH. In terms of management, patient was maintained on empiric antibiotics and aggressive symptom management in the ICU. However, as the diagnosis of HLH became clear, her condition deteriorated rapidly. Emergent Hematology consultation was obtained for initiation of HLH-94 protocol. Dexamethasone and Etoposide were started but our patient succumbed soon after. It was realized that earlier identification of this pattern could have led to sooner initiation of therapy and could have been potentially life saving. Post-mortem analysis was obtained, and is pending at this point. We attempt to throw light on a rare presentation of a fatal disease in a hope that similar cases are identified early and treated.