[617] Benign Signet Ring-Like Cells in Follow-Up Biopsies of Patients with Gastric Lymphoma in Remission – A Rare but Significant Diagnostic Pitfall.

Nicole Durie, Mihai Merzianu. Roswell Park Cancer Institute, Buffalo

Background: Benign signet ring-like cells (SRLC) have been reported in gastric mucosa involved by extranodal marginal zone lymphoma (ENMZL) both in biopsy and resection specimens. The prevalence of SRLC in post therapy follow-up biopsies in patients in clinical remission has not been studied to date.
Design: A pathology database search for gastric lymphoma cases between 1996-2010 was performed. Each biopsy was assessed for presence of SRLC, dysplasia, intestinal metaplasia, inflammation, fibrosis, edema, and regenerative atypia. Review of endoscopic findings and additional studies (AE1/AE3 and mucicarmine) were performed in positive cases.
Results: The study included 28 patients with gastric lymphoma, 17 male and 11 female, median age 62 (range 22-91). 18 had ENMZL and 10 other B cell neoplasms (BCN). In the ENMZL group, 45 of 149 biopsies showed active lymphoma and 104 were post-therapy, negative follow up biopsies (NFB). In the BCN group, 12/26 samples had lymphoma and 14 were NFB. SRLC were identified in 3/104 (3%) NFB samples in the ENMZL group from 2/18 (11%) patients, but not in the BCN group. One ENMZL patient showed SRLC in two non-consecutive follow-up biopsies, at 2 and 4 years after the original lymphoma diagnosis, both interpreted as signet ring carcinoma. A distal gastrectomy was performed following the second diagnosis, no tumor being identified in the resection specimen. Vague nodularity in the area of previous lymphoma and a pre-pyloric ulcer were noted on endoscopy at 2 and 4 years, respectively. The second ENMZL patient showed mucicarmine-negative SRLC at 5 years after diagnosis, with only GEJ nodularity endoscopically. The SRLC were forming small clusters in 2 biopsies and large clusters/sheets in one biopsy, in the latter SRLC being focally positive for mucicarmine and diffusely expressing AE1/AE3. Focal erosion without significant inflammation was seen in one biopsy only but no other significant morphologic findings were associated with SRLC. Both patients had no evidence of lymphoma or carcinoma at last follow up, 2 and 5 years after SRLC finding, respectively.
Conclusions: Epithelial SRLC are a rare but well documented occurrence associated with gastric ENMZL. Our current data suggests that this cellular disaggregation phenomenon can persist for a long time in few patients following eradication of their primary lymphoma, can be found in grossly unremarkable mucosa and are not associated with inflammation. Pathologist's awareness and correlation with clinical history are essential to avoid misinterpretation of SRLC and unnecessary therapy.
Category: Gastrointestinal

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 147, Tuesday Morning


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