Intraoral Basal Cell Carcinoma: Controversies and Insights From a Systematic Review.

Background: The existence of intraoral basal cell carcinoma (IOBCC) remains controversial, despite reported cases in the literature.

Materials and methods: A systematic search of four electronic databases and grey literature was conducted. Strict inclusion criteria were established to define a true case of IOBCC, including Ber-EP4 positivity to distinguish it from peripheral ameloblastoma and the absence of a history of skin lesions-either nearby, which could indicate direct infiltration, or at distant sites, which could suggest metastasis rather than a true primary IOBCC.

Results: A total of 9 cases met the inclusion criteria. IOBCC lesions were located on the palate, buccal mucosa and gingiva, with no cases involving the tongue or floor of the mouth-common sites for squamous cell carcinoma. Histologically, islands of basaloid cells with peripheral palisading and stromal retraction were the predominant findings. All cases were Ber-EP4 positive. Six patients remained disease-free during follow-up, one experienced multiple recurrences, and two had no follow-up data.

Conclusion: IOBCC is extremely rare, with few documented cases. While previous studies suggested the gingiva as a common site, this review found no clear predilection, and some previously reported cases may have been misdiagnosed as peripheral ameloblastoma. Ber-EP4 positivity in IHC is valuable for distinguishing between these entities. Additionally, by excluding cases with potential infiltration from skin lesions, this review underscores the importance of a thorough dermatological evaluation to rule out cutaneous extension or metastasis.