Background: Atypical Acinar Adenosis or Atypical Small Acinar Proliferation (ASAP) is defined as suspicious atypical foci that do not complete a diagnosis of malignancy. (1) These are lesions that are suspected to be malignant, but lack completely satisfactory findings to meet the criteria of malignancy established for prostate cancer. Atypical acinar adenosis (ASAP) is a valid diagnosis within a category that implies absolute uncertainty. It is diagnosed in 1.5 to 9% of prostate biopsies, and patients with this diagnosis have a 45 - 60% probability of developing malignancy in the lesions described in repeat biopsy. (3) (4) (5). The present investigation is carried out in order to create knowledge on the frequency of this diagnosis in our male population that seeks medical care at the Naval Medical Center. Objectives: To determine the prevalence of the diagnosis of Atypical Acinar Adenosis in the results of prostate trucut biopsies issued by the Department of Pathology of the Naval Medical Center during the years 2010 to 2020. In order to make a comparison with the prevalence described in the literature when determining the frequency of the diagnosis of Atypical Acinar Adenosis in the male population of the institution that is cared for at the Naval Medical Center. Material and methods: A retrospective, observational, descriptive, cross-sectional study was carried out; For this purpose, the surgical histological study registration books of the pathology department were reviewed, from 2010 to 2020. All reports of histological studies of prostate tissue were listed, mainly bilateral transrectal trucut biopsy studies of men with a suspected diagnosis of prostate carcinoma. Subsequently, the variables of interest of each record in the electronic medical record were reviewed and analyzed, and the information was downloaded to the database in Excel format and the total number of histopathological reports with a diagnosis of atypical acinar adenosis and other variables of interest that lead to this diagnosis were quantified. Results: From the analysis of a total of 1006 histological studies of prostate tissue, 33 cases (5.5%) were diagnosed with Atypical Acinar Adenosis, based on the main histological criteria. It was observed that the average age of presentation of ASAP was between 61 - 70 years, with an average age of 66.3 years. The distribution of the type of military rank of the cases of atypical acinar adenosis, was observed to occur more frequently (50%) in high-ranking patients, mainly admirals. There was no distinction between the anatomical laterality of the most frequently affected prostate, with 15 cases on the right side and 14 cases on the left side (46 and 42%).and 4 cases (12%) were presented in which both anatomical sides were affected, however, of the anatomical areas of the same, it was observed that the apex was affected more frequently, with a total of 8 cases (24%) in the right apex and 4 cases (12%) in the left apex. Conclusion: The prevalence of the diagnosis of Atypical Acinar Adenosis obtained (5.5%, 33 cases), is within the parameters reported in the international literature, which ranges from 1.5 to 9%. It can be concluded based on the results of the other variables analyzed, that the pathology staff of the Pathological Anatomy Department of the Naval Medical Center are adequately adhering to the criteria that are standardized to conclude in the diagnosis of ASAP.
