PS1266 CLINICAL ASPECTS, MORPHOLOGICAL ANALYSIS AND IMMUNOHISTOCHEMICAL CHARACTERISTICS OF PATIENTS WITH FOLLICULAR LYMPHOMA IN DUODENUM BIOPSY: CASES WITH RESTRICT DISEASE VERSUS ADVANCED PRESENTATION
Authors: G. Duffles, M. Gonçalves, C. Oliveira, G. Fonseca, F. Blumm, V. Vilela, A. Brandão, F. Santos, H. Visnadi, T. Pereira, L. Tucunduva, O. Baiocchi, C. Arrais, Y. Novis, V. Rocha
Journal: HemaSphere (2019)

Background: Duodenal‐type follicular lymphoma (DFL) is recognized as a distinctive entity by the 2016 WHO classification. The largest series to date described 63 cases, highlighting its indolent form and good prognosis. Despite being defined as restricted to the duodenum, progressions can occur. The differentiation from typical follicular lymphoma with duodenum involvement is still a matter for debate. Aims: To study the pathological and clinical aspects of patients with follicular lymphoma (FL) with duodenal involvement, comparing cases restricted to duodenum with cases presenting with advanced disease. Methods: Retrospective analysis of patients diagnosed with FL by endoscopic duodenal biopsies. Cases reviewed for biopsied layers, architectural pattern, follicular dendritic cell pattern (FDCP), Ki‐67 and IgA expression by neoplastic cells. Patients were divided into restrict duodenum involvement (RDI) and with extra duodenal involvement (EDI), by clinical staging at diagnosis. Results: A total of 26 patients, 50% male and average age of 58 years (39–86). Twenty‐one had pathological revision but 2 did not complete clinical staging and were removed from analysis. In the 19 reviewed, 5 (26%) were with EDI and 14 (74%) with RDI. None patient with EDI had mucosa‐restricted disease, but that feature occurred in 9 (64%) patients with RDI. RDI group presented follicular architecture in 9 patients (64%) and 5 (36%) was follicular and diffuse pattern, while 1 (20%) of the EDI group had follicular architecture and 4 (80%) follicular and diffuse. The so‐called “duodenal pattern”, related to FDCP, was reported in 12 (85%) patients with RDI against 3 (60%) with EDI. KI‐67 varied between 5 – 50% in RDI (average 18%) and between 15 – 40% in EDI (average 22%). There was IgA expression in 9 (64%) patients with RDI and in only 1 (20%) patient with EDI. The figure below illustrates IgA expression. Concerning the clinical aspects, from the 26 patients, 19 (73%) had features in the second portion of the duodenum and 16 (61%) the endoscopic lesions were small white nodules. Of the 18 patients that also had a colonoscopy, 1 had lesions in the distal ileum and other in the colon. At diagnosis, endoscopy was made in 9 (35%) patients as screening and in 12 (46%) over gastrointestinal symptoms (GIS). Most patients were FLIPI 0 or 1 (58%) and all had low grade 1–2 FL. For the treatment analysis, 4 patients were excluded because of insufficient data. In the 22 remained patients, the majority was treated with rituximab (R) monotherapy (n = 10, 45%), followed by watch and wait (36%), chemotherapy (14%) and radiotherapy (5%). Indication of treatment was clear in 14 patients, being GIS the principal one (50%). R maintenance was chosen in 8 (36%) patients, 6 previously treated with R and 2 with chemotherapy. All patients treated achieved complete remission by endoscopy and biopsy but one, assigned to R and with partial remission. There was 1 patient in watch and wait that had a spontaneous remission. With a median follow up of 14.5 months (1–40), none patient died and only 1 patient has progressed (EDI group and with nodal disease). Summary/Conclusion: The RDI group (related to the WHO definition of DFL) had more localized mucosal disease, predominantly with the follicular pattern and with higher expression of IgA. The “duodenal pattern” and Ki‐67 did not seem to separate between RDI and EDI patients. Rituximab monotherapy and watch and wait strategy showed good results in this population. A larger cohort of patients with longer follow up may assess better these results. image