Familial hemophagocytic lymphohistiocytosis in Israel. II. Pathologic findings.

Presented are the pathologic findings in familial hemophagocytic lymphohistiocytosis (FHLH), based on observation of 11 cases from four affected families. The outstanding morphologic feature was a multiorgan involvement with lymphohistiocytic cellular infiltrates. The organs most frequently affected were the bone marrow and lymph nodes and, less frequently, the liver and the brain. The histiocytes in the infiltrates were usually bland and displayed prominent hemophagocytosis. The differential diagnosis of FHLH and the difficulty in distinguishing it from malignant histiocytosis is discussed. In view of the focal distribution of lesions, it is suggested that histopathologic diagnosis of FHLH be made only after evaluation of combined findings in several organs and consideration of the patient's family history as well as the result of the clinical and laboratory investigations.