Diagnosing cancer can be difficult, and delaying diagnosis can cause the cancer to progress and complicate treatment. Oral squamous cell carcinoma (OSCC), the most common type of oral cancer, can mimic benign conditions such as periodontal disease and oral infections, making it difficult to diagnose. Therefore, it is important to identify new diagnostic methods for OSCC.
Now, researchers at Osaka University have identified distinct genetic features that distinguish a rare type of OSCC with a burrowing pattern, Cuniculatum carcinoma, from the more aggressive conventional type of OSCC. These findings will be published in the journal Head and Neck Pathology.
Cuniculatum carcinoma, a rare variant of OSCC, can behave very differently from traditional OSCC. This type grows slowly in a burrow-like pattern, rarely spreads, and usually has a good prognosis, although difficult diagnosis can delay treatment.
“Although shield carcinoma is a malignant tumor, its appearance can overlap with benign lesions and requires very different treatments. In other words, it can be a ‘wolf in sheep’s clothing,’ meaning that diagnosing this rare disease can be difficult even for experts such as pathologists,” explains corresponding author Masaru Hirose. “This uncertainty highlights the need for better tools, including genetic testing, to help pathologists make clearer and faster diagnoses.”
As part of their analysis, researchers reviewed 2,002 cases of OSCC from pathology archives at multiple institutions. They identified 23 cases of OSCC with a “burrowing” growth pattern. Based on an analysis of these 23 cases, they found that Cuniculatum carcinoma has a distinct genetic fingerprint. Pathogenic gene mutations were observed in 87.5% of round carcinoma cases examined.
This result caused great excitement and showed that key oral cancer driver genes, such as TP53 and CDKN2A, are less altered in Cuniculatum carcinoma. However, changes occurred more frequently in other genes, such as FAT1, NOTCH1, PIK3CA, and CASP8, indicating the existence of different genetic patterns. The involvement of these genes may explain the slower growth and lower risk of metastasis of square carcinoma compared with more aggressive oral cancers.
Genetic testing has the potential to be a practical tool for accurate diagnosis and targeted treatment, helping clinicians more reliably identify certain conditions and improve patient care. Our findings suggest that this diagnostic approach may also be useful in diagnosing cusp carcinoma. ”
Lead author Sawako Ono
This research provides a promising step toward making one of the most difficult-to-diagnose oral cancers more easily recognized and treated. By uncovering genetic changes, these insights could bring new hope to people facing this rare and overlooked form of oral cancer.
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Reference magazines:
Ono S. and others. (2026). Genetic landscape of oral carcinoma Cuniculatum and its histological mimicry. Head and neck pathology. DOI: 10.1007/s12105-026-01921-3. https://link.springer.com/article/10.1007/s12105-026-01921-3

