Challenges and pitfalls in the diagnosis of adenocarcinoma not otherwise specified affecting tongue: a case report

Abstract Adenocarcinoma, not otherwise specified (ACNOS) remains a challenging diagnostic entity among salivary gland malignancies, particularly in tumors arising from minor salivary glands, due to its marked morphological heterogeneity and overlap with well-defined carcinoma subtypes. We report a rare case of ACNOS occurring on the ventral surface of the tongue in a 42-year-old female, clinically mimicking a reactive lesion. Histopathological examination revealed a malignant glandular neoplasm with solid and cystic growth patterns, supported by an immunohistochemical profile consistent with ACNOS after systematic exclusion of other entities. This case underscores key diagnostic pitfalls and highlights the importance of integrating morphology with targeted immunohistochemistry in the evaluation of clinically inconspicuous oral lesions.