[Tumors of lymphoid and hematopoietic tissue of spleen: a clinicopathologic analysis of 53 cases].

Objective: To study the clinicopathologic features, diagnosis and differential diagnosis of the tumors of lymphoidand hematopoietic tissue of the spleen(TLTS). Methods: Fifty-three cases of TLTS were selected from the pathologic files from Peking University People's Hospital from April 2002 to April 2017. According to WHO classification of tumors of hematopoietic and lymphoid tissues (2008) and its updated classification (2016), the cases were studied by microscopy, immunohistochemistry and in situ hybridization, combined with the bone marrow biopsy and clinical examination. Results: In 53 cases of TLTS, the male to female ratio was 3.4∶1.0; the mean age was 55.4 years (range 21-76 years), and all patients presented with variable degree of splenomegaly. Laboratory examination showed increased percentage of lymphocyte in peripheral blood in 22 cases, and elevated serum LDH level in 24 cases. Abnormal blood counts were seen in 26 cases pre-operatively, in which 22 cases showed complete or partial correction of these abnormalities post-operatively (84.6%, 22/26). The clinical symptoms included abdominal pain or distension, fatigue, fever, and weight loss, etc. Seventeen cases presented with lymphadenopathy of abdomen or other sites. Bone marrow biopsy was performed in 30 cases, and 19 cases were involved by tumor (63.3%). Of all 53 cases, 43 were diagnosed as primary splenic lymphoma (PSL), and the remaining 10 cases as secondary TLTS. According to Ann Arbor staging, 14 cases were stages Ⅰ or Ⅱ, 6 were stage Ⅲ and 28 were stage Ⅳ. By histopathologic classification, 43 cases of PSL were splenic B-cell marginal zone lymphoma (SMZL; 48.8%, 21/43), diffuse large B cell lymphoma (DLBCL; 23.3%, 10/43), splenic diffuse red pulp small B-cell lymphoma (11.6%, 5/43), mantle cell lymphoma (9.3%, 4/43), follicular lymphoma (4.7%, 2/43), and composite lymphoma (CL, DLBCL and classical Hodgkin lymphoma; 2.3%, 1/43). The remaining 10 cases were chronic lymphocytic leukaemia/small lymphocytic lymphoma (4 cases), hairy cell leukaemia (1 case), hepatosplenic T-cell lymphoma (HSTL; 5 cases), with lesions in other sites. Of the 53 cases of TLTS, 47 were B cell neoplasm (88.7%, 47/53), and the T cell neoplasms were all HSTL(5 cases, 9.4%, 5/53), 1 case was composite lymphoma. In 11 cases of TLTS, EBER in situ hybridization was performed and all cases were negative. Forty eight cases had follow-up data, and the median survival period was 17.0 months(range: 1-96 months). The survival of patients with SMZL and DLBCL were 25.7 and 18.6 months respectively. Thirteen patients died (27.1%, 13/48). The prognosis of those with elevated LDH level, high clinical stage, B symptoms and older than 60 years of age was worse. And the prognosis of DLBCL was worse than that of SMZL. There was no statistically significant difference between these factors and prognosis ( P >0.05). Conclusions: Most TLTS cases present with splenomegaly and abnormal blood counts, and complete or partial remission of blood counts isseen after splenectomy. The most common pathologic types of TLTS are SMZL and DLBCL. Definite diagnosis of TLTS could be made by combining clinical features, histopathology, immunophenotype, genetics, bone marrow biopsy and laboratory examination.