Primary intraosseous squamous cell carcinoma (PIOC) derived from ketarocystic odontogenic tumor is a rare malignant tumor that occurs only in jaw bones without connection to the oral mucosa. Since the source of this lesion is epithelium related in odontogenesis, the World Health Organization (WHO) suggested the term primary intraosseous carcinoma and classified the lesion as an odontogenic carcinoma. The estimated incidence of PIOC originated from an odontogenic cyst is 1–2% of all oral cancers. This entity occurs more frequently in male patients with an average age of 57 years, and the most common location is in the posterior mandibular zone. Its clinical presentation is variable and may occur as a benign odontogenic cyst or associated symptoms such as pain, inflammation, tooth mobility and paresthesia. Radiographically early lesions show the same characteristics of an odontogenic cyst, while in later stages the lesion has aggressive characteristics.

We present a case of an 86-year-old woman with a primary squamous cell carcinoma arising in a keratinizing odontogenic tumor. We describe the pathological and clinical characteristics, and discuss the importance of biopsy and histopathology to make an early diagnosis and treatment, thus ensuring a better prognosis.

Conflict of interest: None declared.