Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening condition caused by an excessive chaotic immune activation. It can be primary or secondary to a trigger such as an auto-immune disease, an infectious process or a malignancy. It is usually associated with hematological malignancies and less frequently with solid tumors. This medical emergency has variable presentations lacking pathognomonic clinical and laboratory findings. The prognosis is usually dismal and is associated with high mortality rates.

Here we report the case of a 45-year-old male patient, previously healthy, who presented with alteration of general status and high-grade fever. Laboratory investigations showed a pancytopenia, with grade IV neutropenia, grade II normocytic anemia and grade III thrombocytopenia. The peripheral smear didn’t reveal any abnormal immature cells, schistocytes, nor evidence of leukoerythroblastic reaction. The fibrinogen was low. The bilirubin was increased with a grade III elevation of transaminases and a grade II elevation of cholestatic liver enzymes. The lactate dehydrogenase (LDH) was 10 times more than the upper limit of normal. The ferritin was quite elevated (12598 ng/mL) and there was a hypertriglyceridemia of 750 mg/dL. The clinical and biological findings were consistent with the diagnosis of HLH which was confirmed by a bone marrow biopsy revealing erythro-phagocytocytic changes. There was also a bone marrow infiltration by carcinoma cells; the immunohistochemistry profile was compatible with a gastro-intestinal primary. The radiological and endoscopic investigations concluded for a newly diagnosed gastric adenocarcinoma, initially presenting with exclusive bone marrow metastasis leading to hemophagocytic lymphohistiocytosis. There were no other associated metastatic sites as usually seen in generalized gastric carcinomas. The clinical condition deteriorated despite the urgent initiation of a standard treatment of HLH. The patient passed away after multi-organ failure.

HLH is an aggressive syndrome. Clinicians must be aware of this rare entity that may be the initial presentation of a certain triggering disorder. The treatment consists of stopping the inflammatory cascade via the HLH treatment protocol followed by the appropriate treatment of the underlying trigger.