Academy of Medical Sciences of I.R. Iran Archives of Iranian Medicine 1029-2977 28 2 2025 02 01 Lactating Adenoma in Pregnancy: Report of Three Cases 124 128 10.34172/aim.28751 EN Julija Cvetković https://orcid.org/0000-0002-2745-9810 Maja Jovičić Milentijević Nikola Živković Miodrag Đorđević Jelena Grujović Goran Radenković Journal Article 10.34172/aim.28751 2024 01 19 2024 10 29 Background: Lactating adenoma is an infrequent benign stromal breast tumor mostly seen during pregnancy and lactation. This report seeks to enhance the literature by presenting three cases diagnosed with this condition, while also highlighting its histological subtypes, immunohistochemical characteristics, and differential diagnoses. Case Presentation: In all three patients, a circumscribed, painless, and mobile mass was found in the breast in the third trimester of pregnancy. Pathohistological examination revealed hyperplastic lobules with glandular formations in back-to-back arrangements showing more or less abundant hobnailing phenomena with intraluminal eosinophilic secretions and inconspicuous myoepithelial cell layer separated by fibrovascular stroma. The immune profile showed positive reaction for cytokeratin 14 and p40 markers, indicating the presence of myoepithelial cells and distinguishing these cases from other breast lesions. Conclusion: Pathohistological and immunohistochemical analysis should be performed to differentiate these lesions from other benign lesions and malignant tumors.