Ruth Roman1, Montse Verdú 1,3, August Vidal 1,3, Miquel Calvo 4, Natalia Rodón1, Beatriz García1, Marta González1 and Xavier Puig1,2,3.
1BIOPAT. Biopatologia Molecular, SL, Grup Assistencia; 2Hospital de Barcelona SCIAS, Grup Assistència; 3Histopat Laboratoris and 4Statistics Department, Universitat de Barcelona. Barcelona, Spain.
INTRODUCTION: Invasive micropapillary carcinoma (MC) is associated with frequent lymph node metastasis and adverse clinical outcome. It has been reported in ovary, breast, urinary bladder, ureter, lung, parotid gland and, recently, in colon. Little is known about the morphological and molecular profile of this type of colonic carcinoma.
AIM: To analyze the clinico-pathologic features and molecular findings of colorectal MC and to compare with non-MC carcinoma.
MATERIAL AND METHODS: Clinicopathological features of a cohort of 333 patients with primary colo-rectal cancer were retrospectively reviewed. All slides avalaible from each tumor were reviewed by two pathologists, looking for the presence of micropapillary pattern (small papillary cell clusters surrounded by lacunar spaces). An estimation of the proportion of this component was recorded. The parameters evaluated in each case included: age, sex, location of primary tumor, tumor size, growing pattern (infiltrative or expansive), grade, depth of invasion (pT), lymphovascular and perineural invasion, nodal status (pN) and number of positive lymph nodes Genetic assesment of microsatellite instability (MIN), chromosome 18q status, p53 and Kras mutation were performed on DNA extracted from sections of formalin-fixed, paraffin-embedded specimens.
RESULTS: Twenty seven cases (8.1%) had micropapillary component, ranging from 10 to 95% of the tumor. They showed higher frequency of infiltrative pattern, lymphovascular and perineural invasion, a higher depth of invasion, and more positive lymph nodes when compared with conventional adenocarcionoma. These differences were statistically significative (p</=0.0001). There were not statistical significative differences in molecular findings between the two groups, but MC had a tendency to carry p53 mutations (p=0.03945).
CONCLUSIONS: Colorectal MC appears to be more aggressive than conventional colorectal adenocarcinoma. They present at a higher tumor stage with frequent lymphovascular and perineural invasion and nodal metastasis compared with conventional adenocarcinoma and have more tendency to carry p53 mutations.