Abstract

Background: Adenoma-like adenocarcinoma is a newly recognized subtype in the WHO classification. This is a very rare form of cancer, accounting for 3 - 9% of colorectal adenocarcinomas. Histologically, this tumor may closely resemble benign lesions, posing a diagnostic challenge and increasing the risk of underrecognition or misdiagnosis in clinical practice. Case presentation: We report two rare cases with distinct clinical and histopathological features. The first case is a 67-year-old female patient with a lesion in the left colon. Histological examination revealed a pure adenoma-like adenocarcinoma characterized by pushing borders, uniform glandular architecture, and absence of a significant stromal reaction. The tumor was diagnosed at stage T2 and showed low CDX2 expression. The second case is a 64-year-old male patient with a rectal lesion. Histology demonstrated the presence of a mucinous adenocarcinoma component with deeper invasion (stage T3) and high CDX2 expression. Conclusion: Adenoma-like adenocarcinoma is a rare variant that may pose diagnostic challenges in histopathological evaluation because of its resemblance to benign glandular lesions. The two cases presented here highlight the importance of recognizing the diagnostic criteria and establishing an appropriate differential diagnosis in routine pathology practice. The observed difference in CDX2 expression is an interesting finding that warrants further investigation in larger cohorts.