Canalicular Adenomas of Minor Salivary Glands: A Systematic Review of Case Reports and Case Series

Background/Objectives: Canalicular adenoma (CaA) is a rare benign salivary gland neoplasm that primarily arises in minor salivary glands. Due to histological overlaps with other benign and malignant tumors, accurate diagnosis remains a challenge. This systematic review aims to comprehensively evaluate the clinical presentation, histopathological features, immunohistochemical (IHC) profiles, treatment modalities, and outcomes of CaA affecting the minor salivary glands. Methods: A systematic search of PubMed, Scopus, ScienceDirect, and Google Scholar was conducted for case reports and case series published in English between 2017 and 2025, following PRISMA guidelines. The review was registered in PROSPERO (CRD42023462417). Eligible studies described canalicular adenoma (CaA) of the minor salivary glands with clinical, histopathological, immunohistochemical, and treatment information. Risk of bias was assessed using the Joanna Briggs Institute tools, and data were synthesized descriptively due to heterogeneity in reporting. Results: Out of 1573 records identified, 23 studies met the inclusion criteria, comprising 44 cases. Canalicular adenoma most frequently affected the upper lip (63.6%), followed by the buccal mucosa and palate. Patients ranged from 29 to 84 years (mean 66 years), with a female predominance. Clinically, lesions presented as slow-growing, painless nodules measuring 2–40 mm. Histopathology consistently demonstrated branching canal-like structures lined by columnar or cuboidal epithelial cells, with immunohistochemistry showing positivity for AE1/AE3, CK7, S-100, and SOX10 and negativity for p63 and α-SMA. Surgical excision was the primary treatment, and recurrence was not reported in any of the 14 cases with documented post-treatment follow-up. Most studies showed moderate to high methodological quality. Conclusions: Canalicular adenoma is a rare benign neoplasm with a strong predilection for older women and for the upper lip. Accurate diagnosis requires correlation of clinical, histological, and immunohistochemical features due to its resemblance to other salivary gland tumors. Surgical management yields excellent outcomes, though multifocality may complicate interpretation of recurrence. Larger multi-institutional studies are needed to refine diagnostic criteria and clarify biological behavior.