Hemophagocytic syndrome. Differential diagnostic aspects in a case of well-differentiated malignant histiocytosis.

Diagnosis of malignant histiocytosis (MH) often resembles the solving of an intricate puzzle consisting of clinical symptoms such as lymphadenopathy, splenomegaly, fatigue, fever, and rapid progression, and hematopathological findings such as the presence of atypical histiocytes, especially in blood and bone marrow smears. The lack of one or more of these criteria may greatly impede diagnosis, as in the case of a 45-year-old male with an unusual hematopathological manifestation of MH. The major clinical findings included panhemocytopenia, splenomegaly, and signs of liver dysfunction with severe jaundice. During life, a definite diagnosis could not be established. Histological and cytological evaluation of the spleen following splenectomy revealed a marked increase in histiocytes/macrophages with pronounced hemophagocytosis. These findings were interpreted as a (benign) hemophagocytic syndrome, possibly related to a viral infection. Extensive serological investigations, however, furnished no evidence of a so-called virus- or infection-associated hemophagocytic syndrome. The patient died 5 months after the onset of disease with symptoms of progressive liver failure. Meticulous histological examination of bone marrow revealed a few patchy tumorous infiltrates consisting of dense pleomorphic histiocytes. Thus, a diagnosis of MH was established. This case of MH was unusual with particular regard to its pronounced hemophagocytosis, slight cytological atypia of the histiocytes, and absence of infiltration of lymph nodes.