Study On Clinicopathological Features,the Relationship With Epstein-Barr Virus And Cytogenetic Features Of Nasal And Pharyngeal Non-Hodgkin's Lymphomas In Shenyang

Introduction and ObjectiveThe nasal cavity and pharynx are the most common initial sites of extranodal lymphomas, next to the gastrointestinal tract. In China, the majority of extranodal lymphomas are nasal and pharyngeal non - Hodgkins lymphomas, especially nasal NK/T cell lymphomas. Nasal NK/T cell lymphoma is a progressive and destructive nasal, midline facial lesion. It has been known variously as necrotic granuloma, malignant granuloma, malignant midline reticulosis, polymorphic reticulosis, lethal midline granuloma and lymphomatoid granulomatosis. At the workshop on nasal and related extranodal angiocentric NK/T cell lymphomas in Hong Kong in October 1994, Jaffe named it nasal NK/T cell lymphoma and considered it as a distinct clinicopathologic entity. The WHO new classification of neoplastic diseases of the hematopoietic and lymphoid tissues formally lists the malignancy as nasal NK/T cell lymphoma. This type of malignant lymphoma occurs frequently in Asia and South America but it is rare in the United States and Europe.Epstein - Barr virus (EBV) is a lymphotropic γ herpes virus. The virus infects 80% - 100% of the human population. Since the first Epstein - Barr virus , Epstein MA, was found in Burkitt' s lymphoma in 1964, it has been shown that the virus causes infectious mononucleosis and is associated with nasopharyn-geal carcinoma, Hodgkin's disease, non - Hodgkins lymphoma and lymphomas in immunocompromised individuals. More recently, the Epstein - Barr virus has been implicated in the pathogenesis of NK/T cell lymphoma.p53 gene, located in 17p13, is a well -known tumor suppressor gene. It has two types; wild type and mutation type. Wild — type p53 participates inDNA damage repairing, cell cycle regulating, apoptosis, inhibiting vessel formation, etc. p53 gene mutations can make the above - mentioned functions lost, and cause tumor. Deletions and mutations of p53 can be related to human 50% ~ 60% tumors, p - catenin is a multifunctional soluble protein in cytoplasm. It is the intermedia molecule which transfers Wnt signal to cell then results in cell proliferation. Therefore, it plays an important role in occurrence and development of tumor. At the same time, as an important factor in intercellular adhesive structure - E — cadherin — catenin, p - catenin plays an important role in cell adhesion.We studied 158 cases of nasopharyngeal non - Hodgkin lymphoma in Shenyang with respect to their clinical features, immunophenotypes, significance of Epstein - Barr virus infection and discussed the significance of CD56 and CD57 in NK/T cell lymphoma diagnosis and the mutations of p53 and p - catenin genes in nasal type NK/T cell lymphoma.Meterials and Methods158 patients with clinically diagnosed NHL were obtained from the Department of Pathology, The Affiliated Hospital of China Medical University, between 1996 and 2003. The samples were fixed in 10% (v/v) buffered formalin and embedded in paraffin. For the immunohistochemical study, consecutive 4u,m -thick sections were cut from the tumor margins. The histological features were examined in sections stained with haematoxylin and eosin ( H&E). Immunohis-tochemistry studies were performed using monoclonal antibodies, against CD3 for T -lymphocytes, CD20 for B -lymphocytes, and CD56 and CD57 for NK cells. All cases were reclassified according to the WHO classification of lymphoma in 2000. We compared CD56 with CD57. In situ hybridization for EBV - encoded small nuclear RNA ( EBER - 1) was performed in 99 cases. Polymerase chain reaction - single strand conformation polymorphism ( PCR - SSCP) was introduced to examine mutation of the fourth, fifth, sixth, seventh and eighth exons where mutation of p53 gene was frequent and the third exon where mutation of p - catenin gene was frequent.Results124 (78.48% ) of the 158 NHL were of T and NK cell neoplasms while the 34 others (21.52% ) were of B cell neoplasms. 158 NHL could be classified into 3 major ommunophenotypes: nasal NK/T cell lymphomas (63. 92% , 101/ 158) , peripheral T cell lymphomas, unspecified (14.56% ,23/158) and B cell lymphomas (21.52% ,34/158). 53.16% (84/158) of the initial sites were in the nasal cavity, 24.68% (39/158) in the tonsil and 22.15% (35/158)in the pharynx. Correlation between lymphomas and initial sites was examined by Chi - square test and significant correlation was found (P < 0. 001 ^2 = 55. 831). Comparing CD56 with CD57 was performed in 78 cases. NK/T cell lymphomas (73 cases) were positive for CD56 but negative for CD57. Few T cell lymphomas (5 cases) were positive for CD3, negative for CD56 and scattered positive for CD57.Using EBER - 1 in situ hybridization, the samples were positive in 85 of 99 cases (85. 9% ) , including 68/70 cases (97. 1% ) of nasal NK/T cell lympho-ma, 10/13 cases (76.9% ) of peripheral T cell lymphoma, unspecified, and 7/ 16 cases (43. 8% ) of B cell lymphoma.11 single - nucleotide substitution mutations were detected in 8 of 20 cases (40% ) : 8 mutations in exon 4 ~8, 3 mutations in intron. 6 cases had a single mutation, 1 had two mutations and 1 had three mutations. 8 were missense mutations leading to amino acid substitutions. G:C—>-A;T transition was predominant (90.9%, 10/11), and only one transversion mutation was found. No specific mutation was observed. One of the 11 (9. 1% ) mutations involved codon 273, which is one of the mutational hot - spots.Eight single - nucleotide substitution mutations of the f$ - catenin gene were detected in six of 20 cases (30% ) : all were missense mutations and comprised seven G:C—>-A;T transition and one A:T—>T-.A transversion.