title: Signet-ring cell carcinoma in gastric biopsies: expecting the unexpected.
abstract: OBJECTIVE
  This study was designed to establish the relative prevalence of intestinal-type and signet-ring carcinoma in gastric biopsy specimens from ambulatory patients, to determine the percentage of signet-ring carcinomas that could be expected based on the available clinical and endoscopic information, and to estimate the likelihood of missing a tumour.
  
  
  METHODS
  We extracted data of all patients with a diagnosis of primary gastric carcinoma from a national pathology database. We then reviewed clinical information and original slides, classified tumours as intestinal or signet-ring-type, and categorised the latter as 'unexpected' (no alarming symptoms, no mention of suspicious lesions) or 'expected' (clinical or endoscopic information suggestive of tumour). Unexpected signet-ring carcinomas were categorised as 'obvious' or 'challenging' (rare signet-ring cells; immunohistochemical stains used to confirm the nature of the infiltrates).
  
  
  RESULTS
  There were 310 109 patients with gastric biopsies; 615 patients had primary gastric carcinoma (359 intestinal and 256 signet-ring-type). Gastric cancer was more common in men (OR 2.54; 95% CI 2.05 to 3.14; p<.0001) for intestinal-type and (OR 1.90; 95% CI 1.48 to 2.42; p<0.0001) for signet-ring cell type). Intestinal-type carcinoma occurred in older patients than signet-ring-type (median age 74 vs 65 years, p<0.001). There were 196 expected and 60 unexpected signet-ring carcinomas; 47 of the 60 unexpected cases were histopathologically obvious. Thus, only 13 signet-ring carcinomas (1 in 25 000 gastric biopsy sets) were truly unexpected.
  
  
  CONCLUSIONS
  Signet-ring carcinoma is a rare finding in gastric biopsy specimens from ambulatory patients; routine due diligence and the clinical/endoscopic information provided are usually adequate to raise pathologists' index of suspicion.
authors.affiliation: Miraca Life Sciences Research Institute, Irving, Texas 75039, USA.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Golembeski
authors.forename: Robert Maximilian
authors.initials: RM
authors.lastname: Genta
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D018279:Carcinoma, Signet Ring Cell / Q000737:chemistry / Q000453:epidemiology / Q000473:pathology*; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D015995:Prevalence; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000737:chemistry / Q000453:epidemiology / Q000473:pathology*; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor