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Monocytoid B-cells appear as a distinct B-cell population in a number of lymphadenopathies but above all in Piringer's lymphadenopathy. Up until now, their assignment to a recognised B-cell subpopulation has not been conclusively achieved. Immunohistological studies have shown characteristics in common with the tumour cells of hairy cell leukemia and also with so-called splenic marginal zone cells. In order to unequivocally clarify their B-cell differentiation stage we have isolated single monocytoid B-cells from immunostained frozen sections and have analysed their immunoglobulin chain gene rearrangements. In addition we have studied the Ig-expression of monocytoid B-cells at both the RNA and protein levels.

An account is given of six cases of familial hemophagocytic reticulosis (familial lymphohistiocytosis). After a period of illness varying from 2 weeks to 7.5 months the infants studied died with pancytopenia, fever and hepatosplenomegaly. Histologic examination revealed three characteristic features: Lymphocyte infiltration of the organs, reduction of the lymphatic and hematopoetic system, histiocytosis with erythrophagocytosis. The etiology of this disease remains obscure. Congenital allogeneity may be a possibility, but further immunologic investigations would be necessary to support this hypothesis.

This is the report of a female infant ten weeks of age, who was admitted to our hospital with hyperpyrexia, hemolytic anemia and disseminated intravascular coagulation. The further course of the disease was characterized by: continuing hemolysis resulting in severe normochromic, normocytic anemia, unrelenting disseminated intravascular coagulation, increasing hepato-splenomegaly with hyperbilirubinemia and ascites. No causative infectious organism could be identified. The infant died at the age of 14 weeks from respiratory insufficiency. Autopsy revealed massive hepato-splenomegaly, ascites and bilateral pneumonia. Histologic evaluation demonstrated lymphohistiocytic infiltrates of the periportal areas of the liver, the spleen and lymphnodes. Meninges were infiltered by macrophages with ingested erythrocytes. Differential diagnosis includes an infection with leptospira icterohemorrhagica (Weils disease) and erythrophagocytosis observed after various viral infections. Also histiocytosis X or malignant histiocytosis has to be taken into consideration. The most probable diagnosis in our patient is that of familiar hemophagocytic reticulosis although the familiarity in our patient was lacking. Intra vitam diagnosis can only be established by liver biopsy which could not be performed in our patient due to the severe coagulation disturbance.