Sinusoidal hematolymphoid malignancy ("malignant histiocytosis") presenting as atypical sinusoidal proliferation. A study of nine cases.

A number of cases of sinusoidal hematolymphoid malignancy ("malignant histiocytosis") in which early lymph node biopsies have not allowed clear separation from benign histiocytic disorders have been observed. Nine such cases in which only a follow-up lymph node biopsy documented their malignant nature are reported. Seven of the nine patients were under 21 years of age; there was an even sex distribution. All had localized or generalized lymphadenopathy and three had hepatosplenomegaly at initial presentation. Histologically, the initial lymph node biopsy specimens showed an atypical sinusoidal proliferation, often with hemophagocytosis, but without sufficient atypia to allow a diagnosis of malignancy. The analysis of the follow-up biopsies, performed from 6 weeks to 5 years after the initial biopsy, showed a progression in histology with an increase in atypia, a greater tendency to efface lymph node architecture, and a decrease in hemophagocytosis. All patients were treated with chemotherapy. Six patients ultimately died; at autopsy, these patients showed a pattern of organ involvement typical of what has been described for malignant histiocytosis.