Clinicopathologic study of 60 cases of urothelial neoplasms with inverted growth patterns: Reclassification by international consultation on urologic disease (ICUD) recommendations

Abstract

<p class="first" id="d3435651e180">Most urothelial neoplasms of the bladder show an exophytic papillary pattern, but some show an inverted growth pattern. In 2004, the World Health Organization (WHO) released a detailed histologic classification system for papillary urothelial neoplasms, but not for inverted forms. The International Consultation on Urologic Disease (ICUD) recommendations of 2012 are applicable to inverted/endophytic papillary lesions as follows: 1) inverted papilloma (IP), 2) inverted papillary urothelial neoplasm of low malignant potential (IPUNLMP), 3) inverted papillary urothelial carcinoma, low grade, non-invasive (IPUCLG-NI), 4) inverted papillary urothelial carcinoma, high grade, non-invasive (IPUCHG-NI), 5) inverted papillary urothelial carcinoma, high grade, invasive (IPUCHG-I). However, only atypical cellular morphology was considered for classification in the 2012 ICUD recommendations, and data to support to validate this new grading system are lacking. </p>