[659] Micropapillary Carcinoma of the Stomach: A Clinico-pathologic Study of 12 Cases

JH Roh, KT Jang, M Joo, CK Park, KM Kim. Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea; Ilsan Paik Hospital, Inje University School of Medicine, Goyang, Korea

Background: Micropapillary carcinoma (MPC) is associated with poor prognosis and extensive lymph node metastases. MPC has been reported in the breast, urinary bladder, ureter, lung, ovary, colorectum and salivary gland. However, only one case was reported in the stomach. This study aims to evaluate clinicopathologic features of MPC in the stomach.
Design: 139 gastric adenocarcinomas having features of micropapillary or papillary were retrieved from surgical pathology files among 12,867 gastrectomy and 827 endoscopic resection specimens. To exclude mucinous adenocarcinoma and papillary adenocarcinoma within lymphatic spaces, PAS and D2-40 immunohistochemical staining were performed. Under strict pathologic criteria, 12 MPCs were diagnosed; 10 from gastrectomy specimens and 2 from endoscopic resection specimens. The clinicopathologic features and immunohistochemical staining results for p53 and Ki-67 were also analyzed.
Results: We identified 12 cases of MPCs (approximate prevalence=0.08%). Nine occurred in the body and 3 in the antrum with a mean size of 5.5cm (range 0.7 to 12). Six cases showed invasion into sbumucosa and 2 each case invaded into proper muscle, subserosa and serosa. Ten cases showed differentiated type tubular or papillary adenocarcinoma in the superficial portion of the tumor. The remaining 2 cases were composed solely with poorly differentiated adenocarcinoma. The proportion of MPC within tumors varied from 5% to 70%. The endolymphatic tumor emboli were found in all cases while lymph node metastases were found in 6 cases (55%) among 11 patients who underwent lymph node dissections. Lymph node metastasis was not observed in almost all T1 carcinomas. Only tumors with more than T2 stage showed extensive lymph node metastasis. On immunohistochemistry, p53 was positive in 9 cases (75%) with strong intensity and Ki-67 proliferation index was high in most of cases (range 10 to 80%). Unexpectedly, staining intensity and percentage of staining for p53 and Ki-67 were similar in both micropapillary and ordinary adenocarcinoma areas. During follow up, two patients were died of disease and one patient showed liver metastasis even after completion of adjuvant chemotherapy.
Conclusions: MPC of the stomach is very rare, but occurs early during tumor progression and associated with more frequent endolymphatic tumor emboli. But the lymph node metastasis is closely associated with T stage rather than proportion of micropapillary patterns.
Category: Gastrointestinal

Tuesday, March 10, 2009 1:00 PM

Poster Session IV # 109, Tuesday Afternoon