BCL-6 expression predicts improved survival in patients with primary central nervous system lymphoma.

PURPOSE: The purpose of this study was to investigate the histogenetic origin of primary central nervous system lymphoma (PCNSL) with respect to stage of B-cell differentiation and to identify prognostic markers in a cohort of patients with PCNSL treated with i.v. high-dose methotrexate therapy. EXPERIMENTAL DESIGN: This study included 33 patients with PCNSL treated with high-dose i.v. methotrexate at the Massachusetts General Hospital for whom archival tumor tissue was available. All 33 patients tested negative for HIV. The lymphomas were morphologically subclassified according to the Kiel system, as modified in the WHO classification. Immunohistochemistry for the following antigens was performed: BCL-6; BCL-2; MUM1; CD10; vs38c; CD138; CD44; p16; and p53. Fluorescence in situ hybridization and multiplex PCR for CDKN2A/p16 were also performed. RESULTS: There were 17 women and 16 men enrolled, with a median age of 60 years. All tumors were diffuse large B-cell lymphomas. Of the 23 cases that could be subclassified, 22 were centroblastic, and 1 was immunoblastic. Twenty-six of 33 tumors were BCL-6+, 6 of 32 tumors were CD10+, 27 of 29 tumors were BCL-2+, 31 of 32 tumors were MUM1+, 11 of 31 tumors were CD44+, 4 of 33 tumors were vs38c+, and 0 of 32 tumors were CD138+. There were 18 of 32 (56%) complete responses and 8 of 32 (25%) partial responses to methotrexate, whereas 6 of 33 (18%) progressed during treatment. Ten patients died of disease. Expression of BCL-6 was significantly associated with longer overall survival (P = 0.002; median survival, 101 versus 14.7 months, with approximately 95% lower confidence limits of 41.7 and 8.8 months, respectively). CONCLUSIONS: In this group of 33 patients with PCNSL, expression of BCL-6 was significantly associated with longer overall survival. BCL-6 warrants further investigation as a potentially important prognostic marker in this disease.

Diffuse large B-cell lymphoma of bone: an analysis of differentiation-associated antigens with clinical correlation.

Twenty-nine patients with diffuse large B-cell lymphomas presenting with bone involvement, including 18 localized primary bone lymphomas (group 1), 2 multifocal primary bone lymphomas (group 2), and 9 patients with extraskeletal disease at diagnosis (group 3), were studied. The tumors were subclassified according to the criteria of the WHO classification and evaluated by immunohistochemistry for expression of antigens associated with germinal center (GC) and non-GC stages of B-cell differentiation (bcl-6, CD10, MUM-1, VS38c, CD138, bcl-2, and CD44). The presence of a BCL-2/IgH gene rearrangement was investigated by polymerase chain reaction. All cases were characterized by similar clinicopathologic and morphologic features and had similarly good overall outcome. The patients (23 males, 6 females, median age 44 years) had tumors in long bones (14), axial skeleton (8), limb girdles (3), and multiple sites (4). Most tumors (24) were centroblastic, with multilobated cells in 12 cases. Almost half of the tumors (14 of 29, 48%) were bcl-6+CD10+ (GC-like), 9 of 29 cases (31%) were bcl-6+CD10- (indeterminate phenotype), and 6 of 29 cases (21%) were CD10-bcl-6- (post-GC like). The indeterminate phenotype was seen only in primary bone lymphoma. MUM-1 was frequently expressed in GC-like and non-GC-like categories. We found no evidence of plasmacytic differentiation by CD138, and VS38c immunoreactivity was distinctly rare (2 of 29 cases). CD44 was detected in 6 tumors, all CD10-. Bcl-2 was expressed by 70% of the tumors, but only 1 of 23 cases tested had a Bcl-2/JH rearrangement by polymerase chain reaction. A survival analysis showed that GC-like tumors had a longer overall survival duration compared with non-GC-like tumors (P = 0.0046). In conclusion, a GC-like immunophenotype characterizes roughly half of large B-cell lymphomas of bone and is associated with an improved survival.

Viral-type orchitis: a potential mimic of testicular neoplasia.

Orchitis of viral or presumed viral etiology is an uncommon cause of testicular pain or enlargement. Rarely orchitis is clinically or radiographically suggestive of neoplasia, resulting in a testicular biopsy or orchiectomy being performed. Between 1978 and 2004, 10 cases submitted in consultation were diagnosed as orchitis at the Massachusetts General Hospital. The patients were from 18 to 37 years of age and presented with testicular enlargement or a mass, pain, or both. Radiographic studies were suspicious for a neoplasm in all 5 cases in which results were available. The patients underwent testicular biopsy (2 cases), orchiectomy (6 cases), biopsy immediately followed by orchiectomy (1 case), or biopsy followed by orchiectomy 3 weeks later (1 case). The cases were submitted with diagnoses that included intratubular seminoma, intratubular germ cell neoplasia, unspecified, Sertoli cell hyperplasia, myeloid sarcoma, and lymphoma. Microscopic examination revealed preservation of the architecture of the testicular parenchyma, typically with hemorrhage and edema, with patchy inflammation in the form of a lymphohistiocytic infiltrate within seminiferous tubules and also between tubules. The intratubular infiltrate usually predominated. Immunohistochemical studies, performed in 7 cases showed a mixture of CD68+ histiocytes and CD3+ T cells, with few B cells (CD20+) and few granulocytes. Follow-up was available in 5 cases; all 5 patients were alive and well 11 months to 10 years after diagnosis. In the rare instance in which a testicular specimen with orchitis is submitted for pathologic evaluation, diagnosis may be difficult. Familiarity with the pathologic changes characteristic of orchitis will help avoid misdiagnosis.