[A Case of Primary Intraosseous Carcinoma Arising in the Odontogenic Cyst of the Mandible].

BACKGROUND

Primary intraosseous carcinoma(IOC)is a rare malignancy originating from the epithelial lining of odontogenic cysts. We present a case of IOC arising from an odontogenic cyst in the mandible.

CASE: A 51-year-old man presented to a general hospital with limited mouth opening. Initial anti-inflammatory treatment was administered for a presumed secondary infected mandibular odontogenic cyst;however, symptoms persisted. Subsequent biopsy revealed squamous cell carcinoma, prompting referred to our department for multidisciplinary management. Various examinations were performed, and the patient was diagnosed with a primary intraosseous carcinoma arising from a mandibular odontogenic cyst. Chemoradiotherapy was planned for this patient with unresectable locally advanced cancer. Three courses of induction chemotherapy were administered, followed by radiation therapy to the primary tumor and bilateral cervical areas(total 72 Gy)with cetuximab(Cmab). Cmab was continued post-radiation;however, the patient failed to respond to treatment and died 1 year and 2 months post-treatment initiation.

DISCUSSION: Primary IOCs are challenging to distinguish from odontogenic cysts. This highlights the importance of definitive diagnosis and early intervention.