The clinicopathological characteristics and diagnosis of non-Hodgkin lymphoma were analyzed,including (1) clinical manifestations:lymph nodes are enlarged with B symptoms including extension and fever;(2) histopathology:dysplasia and clonal proliferation of tumor cells,invasion and destruction of normal tissue structure are noted;(3) immunophenotype:it shows an immunophenotype consistent with histopathology;(4) molecular pathology:molecular pathological tests are performed when morphological and immunohistochemical findings cannot determine benign or malignant lesions.Ig and T cell receptor polymerase chain reaction gene rearrangements detection is commonly used to determine the clonality.When the results of above four aspects are the same,lymphoma can be diagnosed,and if there is any doubt,the diagnosis of lymphoma cannot be made.

The histiocytic necrotizing lymphadenitis (HNL) is a common benign lesion in the clinic. Because of its specificity, it is easy to be misdiagnosed as lymphoma or other benign lesions. The author analyzed the reasons of misdiagnosis as follows: (1) pathologists ignored the background of reactive hyperplasia and the specificity of clinical pathological changes; (2) isolate one-sided understanding of nuclear debris in necrotic foci; (3) a false negative result could be presented in HNL gene rearrangement analysis. The pathologists must fully grasp the clinical and histopathological features and immunophenotypic characteristics of HNL to prevent the misdiagnosis.

Objective To investigate the expression of PAX-5 in anaplastic large cell lymphoma, discuss the value and pitfalls of PAX-5 in the diagnosis and differential diagnosis of lymphomas. Methods A total of 269 T lymphomas were studied retrospectively.PAX-5 positive anaplastic large cell lymphoma was confirmed by immo-munohistochemistry and gene rearrangement analysis. Literature review was performed and the clinicopathological features were discussed.Results Two cases of anaplastic large cell lymphoma were found with aberrant expression of PAX-5. Conclusions As a relatively specific B cell marker, PAX-5 can also express in anaplastic large cell lymphoma. In the diagnosis of lymphomas, especially the differential diagnosis between classical Hodgkin lympho-ma and Anaplastic large-cell lymphoma, diagnosis errors should be avoided by interpreting PAX-5 immunohisto-chemistry in the context of clinical features, morphology, a panel of B- and T-lineage-associated antibodies, and gene rearrangement analysis.

This paper introduces the clinical features, histopathology, immunophenotype and differential diagnosis of reactive hyperplasia (RH) in lymphoid tissues. The characteristics of RH are as follows: (1) Clinical presentations include acute fever and mild enlargement of lymph nodes. The patients can be cured when the causes of disease disappear; (2) Pathological histology is divided into single type and specific type. The common changes of lymphoid tissues are lymph follicle (LF) or T-zone cell hyperplasia, which leads to the disorder of normal tissues, including the increased number of large cells and mitosis (known as the pseudomalignant histological form); (3) Immunophentype is featured by normal pattern of LF and T-zone cells. The key point of differential diagnosis is the overgrowth of cells producing pseudomalignant histological changes in RH, resulting in the lack of cell atypia and monoclonal, damage and erosion of the normal tissue structures.

This article describes the basic pathological diagnosis of lymphoma.The tips should be followed.Firstly,to correctly observe the HE sections of lymph nodes; Secondly,to determine the reference cells of each cell type with different volumes; Thirdly,to properly assess the four elements of pathological diagnosis of benign and malignant hyperplasia in lymphoid tissues.The above three points must be paid attention to improve the accuracy of lymphoma pathological diagnosis.

The immunohistochemistry is an useful method for pathological diagnosis and differential diagnosis of lymphoproliferative lesions,but it must be used correctly and its immunophenotypic results should be evaluated. The following points should be paid attention: (1) Similar antibodies must be reasonable compatibility; (2) the pseudo-positive and pseudo-negative of immunophenotype must be distinguished; (3) the immunophenotypica site must be distinguished; (4) the specify of the antibody expression must be distinguished; (5) the immunophenotype in the tumor cells or reactive cells must be distinguished; (6) the immunophenotype must be used correctly in differential diagnosis between the benign and malignant of hyperplastic lymphoid tissues. The author emphasizes that immunohistochemical techniques need to be combined with other diagnostic features of lymphoproliferative lesions,in order to obtain satisfactory results.

Purpose　To explore the clinicopathological features of subcutaneous panniculitic T-cell lymphoma(SPTCL) and significances of genetic analysis in the diagnosis. Methods　Histopathology, immunohistochemitry and detection of clonal gene rearrangement by PCR were used in 3 cases of subcutaneous panniculitic T-cell lymphoma (SPTCL), which were originally diagnosed as relapsing nodular nonsuppurative panniculitis. Results　Three misdiagnostic cases were correctly redefined as subcutaneous panniculitic T-cell lymphoma, with immunophenotype of CD45+,CD45RO+, Mac387－,and clonal TCR-β gene rearrangement. Conclusions　Subcutaneous panniculitic T-cell lymphoma has distinctive clinicopathological features. Genetic analysis is an effective method for the diagnosis of SPTCL.

AIM: To study the expression of mic2/CD99 protein and their correlation with Eber-1/LMP-1 in Hodgkin and Reed-Sternberg cells of classical Hodgkin's lymphoma. METHODS: Immunohistochemical staining, in situ hybrization and tissue microarry technique were used to detect the expressions of mic2/CD99 and Eber-1/LMP-1 of H/RS cells in 43 cases of cHL and 16 cases of NHL. RESULTS: The positive rate of CD99 protein expression in 43 cases of cHL was 2.3% (1/43) , mic2 was 55.8% (24/43), LMP1 was 58.1% (25/43) and Eber-1 was 53.5% (23/43). The expressions of CD99 and mic2 in the NHL group were higher than those in cHL group (P0.05). There was a negative correlation between the expression of CD99 protein and LMP1 in H/RS cells (P0.05). There was a significant correlation between the high expression of LMP1 and a low expression of CD99 in the young patients (P0.05). CONCLUSION: There is a negative correlation between the expression of LMP1 and CD99 in Hodgkin and Reed-Sternberg cells of classical Hodgkin's lymphoma.

The histological features of 22 cases of lymphofollicular tumor-like hyperpla-sia and 16 cases of follicular lymphoma were reviewed in order to find out certain criteria to differentiate the former from the latter. It was suggested that an integral consideration of the pleomorphism and the relative monomorphism of the cells of which a follicle consists, the presence or absence of the tingible body macrophages, and the presence or absence of the mantle zone of the small lymphocytes should be imperative in the differentiation of follicular hyperplasia from follicular lyrnphoma. Other signs such as the back to back position of the follicular follicles is of little significance in the differentiation since it is a normal phenomenon of the growth and enlargement of follicles.

Fresh lyraphoreticular tissues obtained from 14 cases of chronic hyperplastic tonsillitis and 4 cases of reactive hyperplasia of tonsils were studied for the enzymic activity of the acid ?-Naphthyl acetate esterase(ANAE). Imprints of the fresh lymphoreticular tissues were made. Then they were fixed according to the Mueller's method. Cryostal frozen section and paraffin section with ANAE stain were made. A part of the fresh lymphoreticular tissues was fixed with 10% formalin solution. Finally, cryostal frozen section and paraffin section with ANAE stain were made of the formalin-fixed tissues on the 10th, 20th and 30th day of fixation respectively.The rates of the cells positive for dot-like positions of different preparations were compared. It was found that the positive rate was the highest in the fresh frozen sections, then in the fresh imprints and fresh paraffin sections. The longer the tissues were preserved with formalin, the lower the rate of the posititive cells. The positive rate was nearly zero in the tissues after 30 days of formalin fixation.