Oral carcinoma cuniculatum, a rare variant of squamous cell carcinoma

Carcinoma cuniculatum (CC) is a rare variant of squamous cell carcinoma (SCC). Lack of awareness of this tumor and its difficult diagnosis delay management and complicate treatment. The aim of this study is to describe the clinical and histological features, predisposing factors, treatment and survival rate of oral carcinoma cuniculatum.

All patients with histologically confirmed CC of the oral cavity treated between January 2013 and August 2022 in a specialized center were retrospectively included. Patients were identified using the database ADICAP ("Association pour le Développement de l'Informatique en Cytologie et Anatomie Pathologique"). Once identified, the charts were reviewed.

Ten patients were included. CC lesions were mainly located in the mandibular or maxillary gingiva, while the 2 remaining lesions were located in the mobile tongue. The tumor showed local aggressiveness: mandibular or maxillary osteolysis was systematically found for gingival CC, while tongue lesions were classified cT3. Fifteen biopsies were performed in these 10 patients, histological diagnosis is difficult on a limited tissue sample. All patients underwent curative management with oncological excision surgery combined with neck lymph node dissection, and adjuvant radiotherapy (except one patient).

The main problem is the difficulty of diagnosis when biopsies are performed, which leads to a significant delay in diagnosis compared with SCC. In the event of clinico-histological discordance after biopsy, CC should be considered.