title: Micropapillary component in gastric adenocarcinoma: an aggressive variant associated with poor prognosis.
abstract: BACKGROUND
  Adenocarcinomas with a micropapillary component (MPC) have been described as an unusual morphological variant in various organs. However, few reports have described MPCs in gastric carcinomas, and the clinicopathological features of MPC are unclear.
  
  
  METHODS
  Immunohistochemistry was used to detect the expression of epithelial membrane antigen, CK7, CK20, p53, epidermal growth factor receptor, β-catenin, c-erbB-2, and Ki-67. Correlation of the MPC to tumor stage, lymph node metastasis, and lymphovascular invasion was performed using Fisher's exact test. Kaplan-Meier estimates were used to analyze overall survival.
  
  
  RESULTS
  Immunohistochemical staining demonstrated that micropapillary and conventional gastric carcinomas showed similar positivity rates for all markers. However, aberrant expression of E-cadherin was detected in the tumors with MPCs without immunoreactivity in the stroma face. Epithelial membrane antigen showed the characteristic inside-out staining pattern of MPCs. Lymphatic invasion (P = 0.003), venous invasion (P = 0.017), lymph node metastasis (P = 0.014), and tumor stage (P = 0.022) were significantly increased in patients with MPCs when compared with conventional adenocarcinomas. MPC subtype II had a significantly higher frequency of lymph node metastasis than subtype I (P = 0.014). However, the proportion of MPC was not associated with lymph node metastases (P = 0.136). Overall survival of patients with an MPC was significantly shorter than that of patients with conventional adenocarcinomas (P = 0.031). In addition, overall survival was significantly lower in patients with a subtype II MPC growth pattern than in those with subtype I MPC in gastric carcinomas (P = 0.040).
  
  
  CONCLUSIONS
  Gastric adenocarcinomas with MPC appear to be an aggressive variant associated with a poor prognosis. MPCs occurring in gastric adenocarcinomas should be included in surgical pathology reports, even if the proportion of MPC in the lesions is very low in the lesion.
authors.affiliation: Department of Pathology, the First Affiliated Hospital and College of Basic Medical Sciences, China Medical University, No. 92 North Second Road, Heping District, Shenyang, 110001, China.
authors.forename: Qingfu
authors.initials: Q
authors.lastname: Zhang
authors.forename: Jian
authors.initials: J
authors.lastname: Ming
authors.forename: Siyang
authors.initials: S
authors.lastname: Zhang
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.forename: Liying
authors.initials: L
authors.lastname: Yin
authors.forename: Xueshan
authors.initials: X
authors.lastname: Qiu
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000401:mortality / Q000473:pathology*; D000231:Adenocarcinoma, Papillary / Q000378:metabolism / Q000401:mortality* / Q000473:pathology; D000368:Aged; D015820:Cadherins / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D013274:Stomach Neoplasms / Q000378:metabolism / Q000401:mortality* / Q000473:pathology*
chemical_list: D015820:Cadherins; D066246:ErbB Receptors; D018719:Erb-b2 Receptor Tyrosine Kinases; C512478:EGFR protein, human; C508053:ERBB2 protein, human