Dumler J S, Dawson J E, Walker D H
Department of Pathology, University of Texas Medical Branch, Galveston.
Hum Pathol. 1993 Apr;24(4):391-6. doi: 10.1016/0046-8177(93)90087-w.
Human ehrlichiosis is a recently described zoonosis caused by a rickettsia that infects leukocytes. Most patients have fever, headache, chills, and myalgias and develop leukopenia, thrombocytopenia, anemia, and elevations in serum hepatic aminotransferases. The cause of the peripheral leukopenia and thrombocytopenia is not known. We studied peripheral blood smears, bone marrow aspirates, and bone marrow biopsy specimens from patients with serologically proven ehrlichiosis to characterize the pathologic changes associated with leukopenia or thrombocytopenia, to detect the presence of immunohistologically demonstrable ehrlichiae, and to establish the infected host target cell(s). Specimens were obtained from 12 patients, and immunohistology for Ehrlichia chaffeensis was performed on tissue sections, aspirated bone marrow, and peripheral blood smears. Mean leukocyte and platelet counts available for nine patients were white blood cell count 3,300/microL (range, 1,100 to 10,300/microL) and platelets 61,000/microL (range, 40,000 to 82,000/microL). Findings included myeloid hyperplasia (eight cases), megakaryocytosis (seven cases), granulomas (eight cases), marrow histiocytosis (one case), myeloid hypoplasia (one case), pancellular hypoplasia (one case), and normocellular marrow (two cases). Morulae of E chaffeensis were detected in four of 10 cases examined by immunohistology. Most ehrlichiae were detected within histiocytes, although morulae were rarely present within lymphocytes. Leukopenia, thrombocytopenia, or pancytopenia apparently most often results from peripheral sequestration or destruction; however, hypoplasia of marrow elements is present occasionally. Immunohistologic demonstration of E chaffeensis offers a direct means for establishing the etiologic diagnosis. These observations show the relatively frequent occurrence of bone marrow granulomas and suggest that infection of cells of the reticuloendothelial system may participate in the pathogenesis of human ehrlichiosis.
人埃立克体病是一种最近才被描述的人畜共患病，由一种感染白细胞的立克次体引起。大多数患者有发热、头痛、寒战和肌痛，并出现白细胞减少、血小板减少、贫血以及血清肝转氨酶升高。外周血白细胞减少和血小板减少的原因尚不清楚。我们研究了血清学确诊的埃立克体病患者的外周血涂片、骨髓穿刺物和骨髓活检标本，以明确与白细胞减少或血小板减少相关的病理变化，检测免疫组织学可证实的埃立克体的存在，并确定受感染的宿主靶细胞。从12例患者获取标本，对组织切片、骨髓穿刺物和外周血涂片进行查菲埃立克体的免疫组织学检查。9例患者的平均白细胞和血小板计数分别为白细胞计数3300/μL（范围为1100至10300/μL），血小板61000/μL（范围为40000至82000/μL）。检查结果包括骨髓增生（8例）、巨核细胞增多（7例）、肉芽肿（8例）、骨髓组织细胞增多（1例）、骨髓发育不全（1例）、全血细胞发育不全（1例）和正常细胞骨髓（2例）。在免疫组织学检查的10例中有4例检测到查菲埃立克体的桑葚体。大多数埃立克体在组织细胞内被检测到，尽管在淋巴细胞内很少有桑葚体。白细胞减少、血小板减少或全血细胞减少显然最常是由于外周隔离或破坏所致；然而，骨髓成分发育不全偶尔也会出现。查菲埃立克体的免疫组织学证实为病因诊断提供了直接手段。这些观察结果表明骨髓肉芽肿相对常见，并提示网状内皮系统细胞的感染可能参与人埃立克体病的发病机制。
