Atypical Polypoid Adenomyoma (APA) is a benign uterine lesion that occurs in women of reproductive age. The histological pattern is characterized by irregular epithelial proliferation and muscular stroma. Our work consists of a systematic review of the literature, including the description and analysis of a case study, and assesses the main immunohistochemical and molecular markers that contribute to making a differential diagnosis against endometrial adenocarcinoma. This allows offering patients conservative treatment compared to the radical management required for endometrial cancer, due to the significant physical and psychological consequences that one procedure or another can have on women's health. The goal of this research is to carry out an adequate diagnosis of APA by providing the necessary information to guide clinical management, establish patient prognosis, and minimize the emotional impact associated with the disease, all in combination with clinical and histopathological findings and complementary imaging tests. In conclusion, an appropriate immunohistochemical and molecular approach, along with the presumptive histological diagnosis, determine the correct classification of the lesion as APA and not as other malignant pathologies, which allows establishing a treatment protocol adjusted to the biological reality of this pathology.

Hyperplastic nodules (HNs) are benign polypoid lesions of the colorectal mucosa reportedly caused by hyperplasia of the crypt epithelial cells. They differ from hyperplastic polyps because the crypts do not have histologically serrated changes. HNs often occur in the rectal mucosa and tend to be multifocal. We have proposed a new colitis nucleomigrans (CN) concept as the third type of microscopic colitis. Our histopathological criteria of CN include: i) chained nuclear migration to the middle part of the surface-lining columnar epithelium, ii) apoptotic nuclear debris scattered in the eosinophilic cytoplasm underneath the nuclei, and iii) mild to moderate chronic inflammation in the lamina propria. Immunostaining for cleaved-caspase 3 revealed apoptotic bodies. In this study, we report that most HN lesions share the histological features with CN, representing polypoid CN. We evaluated 108 lesions of HN in total, and 94 (87%) were reclassified as polypoid CN. In the polypoid CN, the lamina propria mucosae were uniformly edematous, suggesting that accelerated apoptosis of the mucosal surface epithelium may cause osmotic dysregulation to form localized mucosal elevations.