Hemophagocytic histiocytosis: A Clinicopathological correlation

OBJECTIVES: Histiocytic hyperplasia with hemophagocytosis (HP) is relatively uncommon condition that has often been mistaken in the past for neoplastic disorders. This study was conducted to investigate the possible etiology of HP, its intensity in the bone marrow (BM), and also its effect on hematological parameters with the extent of disease activity. METHODS: Blood samples were collected and BM examination was performed in 250 patients with varied etiology showing HP. Complete blood counts, reticulocyte count, and red blood cell morphology were determined. HP was examined in the BM smears by Leishman staining. The severity of HP was determined by grading of its intensity in the BM smears. RESULTS: Our data showed variable degree of HP (mild, moderate, and severe) in the BM smears of patients having different underlying disorders. HP syndrome (HPS) with clinical and biochemical derangements was found in 24 (9.6%) patients. HPS was mostly associated with infection. The etiological distribution in different group of disorders was nonmalignant hematological conditions (56.80%), infections (24.80%), storage disorders (4.40%), malignant hematological conditions (4.40%), autoimmune disorders (1.20%), and miscellaneous group (8.40%). Distribution of patients in different grades of intensity of HP was Grade I (35.50%; mild), Grade II (45.50%; moderate), and Grade III (19.60%; severe). CONCLUSION: We conclude that severe degree of HP has profound effect on hematological parameters particularly hemoglobin and platelet counts. This phenomenon may present as HPS with fatal outcome. We also conclude that there was no effect of age on either intensity of HP or on blood counts.