Cellular Proliferation Index between Carcinoma Ex-Pleomorphic Adenoma and Pleomorphic Adenoma

Carcinoma ex pleomorphic adenoma (CXPA) has been considered an interesting model of carcinogenesis, presenting various histological subtypes and invasiveness phase. The objective was to determine the proliferative index of CXPA and comparing to pleomorphic adenoma (PA). Thirty six cases of CXPA (36 PA) and 22 areas of PA in CXPA (residual PA) were studied by Ki-67 expression. All CXPA cases were classified according to invasiveness phase (intracapsular, minimally and frankly invasive) and histopathological subtypes. Data was statistically analyzed by Wilcoxon, Mann-Whitney and Kruskal-Wallis tests. CXPA included 5 intracapsular, 9 minimally invasive and 22 frankly invasive cases. Fifteen cases corresponded to salivary duct carcinoma, 7 to adenocarcinoma NOS, 7 myoepithelial, 5 epithelial-myoepithelial, one case of squamous cell and one case of sarcomatoid carcinoma. The Ki-67 index of PA and residual PA were significantly lower than CXPA. Intracapsular and minimally invasive showed smaller proliferative index than frankly invasive. Considering the subtypes of CXPA, there was not a statistic difference among them. Ki-67 is a useful marker in the differential diagnosis of PA and CXPA, even when in the early invasive phase. Carcinoma ex adenoma pleomorfo (CXAP) tem sido considerado um interessante modelo de carcinogênese, apresentando vários subtipos histológicos e fases de invasividade. Determinar o índice proliferativo de CXAP e compará-lo ao adenoma pleomorfo (AP). e seis casos de CXAP, 36 AP, e 22 áreas de AP em CXAP (AP residual) foram estudadas através da expressão de Ki-67. Todos os casos de CXAP foram classificados de acordo com a fase de invasividade (intracapsular, minimamente invasivo e francamente invasivo) e de acordo com os diversos subtipos histopatológicos. Os dados foram estatisticamente analisados através dos testes Wilcoxon, Mann-Whitney e Kruskal-Wallis. O grupo de CXAP era formado por 5 intracapsulares, 9 minimamente invasivos e 22 francamente invasivos. Quinze casos corresponderam a carcinoma de ducto salivar, 7 a adenocarcinoma nos, 7 a carcinoma mioepitelial, 5 a carcinoma epitelial-mioepitelial, 1 a carcinoma epidermoide e 1 a carcinoma sarcomatóide. Os índices de Ki-67 de AP e AP residual foram significativamente menores que o encontrado em CXAP. Os casos intracapsulares e minimamente invasivos mostraram índices proliferativos menores que os francamente invasivos. Considerando os subtipos histológicos de CXAP, não houve diferença est