目的：总结婴幼儿恶性组织细胞增生症（恶组）的临床病理特点和分型。方法：对５例尸检材料进行光镜观察和免疫组化（Ｓ－Ｐ法）染色。结果：２例具有高热、肝脾肿大和全血降低三联征，恶组细胞浸润脏器较多、程度较重并伴免疫缺陷性病变。２例临床经过短促（死于并发症），无典型临床表现，受累脏器较少、程度较轻。１例主要表现为全身出血性皮疹、巨脾和肺实变，病理组织学上亦有勒雪氏病某些改变。免疫组化结果，ＡＡＣＴ和ｌｙｓｏｚｙｍｅ阳性而ＬＣＡ基本阴性。结论：婴幼儿恶组可分为经典型、亚临床型及勒雪氏病型，免疫组化结果支持恶组细胞来源于组织细胞／单核细胞的观点。 Objective: To summarize the clinicopathological features and classification of infantile malignant histiocytosis (malignant group). Methods: Five cases of autopsy materials were stained with light microscopy and immunohistochemistry (S-P method). Results: Two cases had high fever, hepatosplenomegaly and whole blood to reduce triad of levy, malignant cell infiltration of organs more severe and with immunodeficiency lesions. 2 cases of clinical short-term (died of complications), no typical clinical manifestations, fewer organs involved, to a lesser extent. One case mainly manifested as systemic hemorrhagic rash, splenomegaly and lung consolidation, histopathology also have some changes in lech’s disease. Immunohistochemical results showed that AACT and lysozyme were positive while LCA was almost negative. Conclusion: The evil group of infants and young children can be divided into classic, subclinical and lech’s disease types. The results of immunohistochemistry support the view that the malignant cells originate from the tissue cells / monocytes.