The pathogenesis of multiple myeloma (MM), an incurable tumour causing the deregulated proliferation of terminally differentiated B cells, is unknown. Chromosomal translocations (14q1) affecting band 14q32 and unidentified partner chromosomes are common in this tumour, suggesting that they may cause the activation of novel oncogenes. By cloning the chromosomal breakpoints in an MM cell line, we show that the 14q+ translocation represents a t(6;14)x(p25;q32) and that this aberration is recurrent in MM, as it was found in two of eleven MM cell lines. The translocation juxtaposes the immunoglobulin heavy-chain (IgH) locus to MUM1 (multiple myeloma oncogene 1)/IRF4 gene, a member of the interferon regulatory factor (IRF) family known to be active in the control of B-cell proliferation and differentiation. As a result, the MUM1/IRF4 gene is overexpressed--an event that may contribute to tumorigenesis, a MUM1/IRF4 has oncogenic activity in vitro. These findings identify a novel genetic alteration associated with MM, with implications for the pathogenesis and diagnostics of this tumour.

Although the gastrointestinal tract represents the most common site of extranodal lymphoma, primary follicular lymphoma of the gastrointestinal tract is an uncommon and poorly defined disease. We report the clinical and pathologic features of 26 patients with primary gastrointestinal follicular lymphoma. Ten of 26 patients (38.5%) were stage IIE, and 16 patients (61.5%) were stage IE. Of the 26 patients, 13 were female and 13 were male. The age range was 26-81 years (median 54.5 years). Abdominal pain was the most common presenting symptom, seen in 12 of 24 patients (50%). Nodularity of the mucosal surface was the most common endoscopic finding, seen in 10 of 14 patients (71.4%). The majority of cases (22 of 26, 84.6%) involved small bowel, four involved colorectum alone, and two involved the ileocecal valve. Within the small bowel the duodenum was the most commonly involved site (10 cases). Transmural involvement by follicular lymphoma was identified in 11 of the 16 patients who underwent surgical resection; five showed involvement of mucosa and submucosa only. The most common histologic grade was grade 1. Thirteen of 26 cases were grade 1, ten grade 2, and three grade 3. Twenty-one of 26 cases showed a predominantly follicular growth pattern, four mixed follicular and diffuse, and one predominantly diffuse. All cases were positive for CD20 and BCL2 and negative for CD3, CD5, CD23, CD43, and cyclin D1. Twenty-four of 26 were positive for CD10. Four of four cases showed cytogenetic or molecular genetic evidence of t(14;18). Initial treatment modalities included surgery plus chemotherapy (nine cases), surgery alone (seven cases), chemotherapy alone (four cases), observation alone (four cases), and chemotherapy and abdominal radiation (one case). One case presented with rectal polyps and was treated with polypectomy. A complete response was observed in 15 of 22 cases that received treatment, and of the 15 cases, five recurred 27-60 months after the initial diagnosis. Recurrence and progression were associated with histologic transformation to diffuse large cell lymphoma in one case. No significant correlation was identified between treatment response and various clinical and pathologic features. Overall, none of the 26 patients died of lymphoma. One patient died of a concomitant pancreatic carcinoma. Of the remaining 25 patients, 14 were disease free and 11 were alive with disease at a mean follow-up of 43 months. The estimated 5-year disease-free survival was 62%, and median disease-free survival was 69 months. The estimated 5-year relapse-free survival was 54%, and the median relapse-free survival was 63 months.

The association between cancer and immunodeficiency is well established. In common variable immunodeficiency (CVI), a primary immunodeficiency disease characterized by low serum immunoglobulins and poor antibody production, we previously reported a total of 13 cancers in 11 individuals arising in continuously observed group of patients. Of the 13, 7 were NHL and 1 was a myeloma which progressed to lymphoma. We report here the histologic, immunologic, cytogenetic, and clinical features of these 8 NHL along with 3 new lymphomas which have appeared in this group (now 117 patients). From our studies, the lymphomas which have arisen in CVI share certain features with the lymphomas which appear in the childhood immunodeficient syndromes. Wiskott Aldrich Syndrome, Ataxia Telangiectasia, or severe combined immunodeficiency: they are similar in overall frequency (13%), are often B-cell in origin, and extranodal in location. However, unlike the lymphomas of the immunodeficient child, lymphomas in CVI may be more differentiated and secrete immunoglobulin. For CVI patients with stage I or II disease, as for non-Hodgkin lymphomas in general, the prognosis is good. In our group, NHL in CVI have appeared most often in females of the 5th to 7th decade and not in childhood. Cytogenetic studies in lymphomas show that cytogenic abnormalities, including chromosomal translocation, can be found in this group, but more studies will be needed to assess the frequency of these events.

The pathogenesis of non-Hodgkin's lymphoma (NHL) with a large cell component (DLLC, including diffuse large cell, DLCL; diffuse mixed cell, MX-D; and immunoblastic, IMB) is unknown. A novel candidate proto- oncogene, BCL6, that is involved in chromosome band 3q27 aberrations in NHL has been recently identified. We have investigated the incidence and disease-specificity of BCL6 rearrangements in a large panel of lymphoid tumors, including acute and chronic lymphoid leukemias (96 cases), various NHL types (125 cases), and multiple myelomas (23 cases). BCL6 rearrangements were found in 16/45 (35.5%) DLLC, more frequently in DLCL (15/33, 45%) than in MX-D (1/10, 10%), in 2/31 (6.4%) follicular NHL, and in no other tumor types. BCL6 rearrangements represent the first genetic lesion specifically and recurrently associated with DLLC and should prove useful for understanding the pathogenesis as well as for the clinical monitoring of these tumors.

The majority of low-grade non-Hodgkin's lymphomas (NHL) undergo clinical progression toward intermediate- and high-grade lymphomas. This progression is often associated with histologic transformation from follicular to diffuse-type NHL. The pathogenetic mechanisms underlying this evolution are presently unknown. In this study, we have analyzed the role in NHL progression of relevant genetic lesions affecting proto-oncogenes and tumor suppressor genes. Sequential biopsies from 21 patients with clinical progression with (5 cases) or without (16 cases) evidence of histologic transformation were analyzed for karyotypic changes, c-myc rearrangements and deletions affecting 6q27 by Southern blot analysis, and p53 mutations by single-strand conformation polymorphism (SSCP) analysis coupled with direct sequencing of polymerase chain reaction-amplified products. No novel cytogenetic aberration was detected in association with progression, and all samples analyzed displayed a normal c-myc gene. Mutations of the p53 gene were detected in 4 of 5 cases displaying histologic transformation from follicular to diffuse-type NHL and in none of the 16 cases displaying clinical progression in the absence of histologic transformation. In 1 of these positive cases, the same mutation was also present in the pretransformation biopsy, correlating with the presence of diffuse-type areas within a predominant follicular pattern. In 1 of these cases, a deletion of 6q27 was also detected in the posttransformation biopsy along with a p53 mutation. These findings indicate that p53 mutations are associated with and may be responsible for histologic transformation of follicular lymphoma.