Primary Intraosseous Squamous Cell Carcinoma of the Mandible: A Rare and Challenging Case.

Primary intraosseous squamous cell carcinoma (PIOSCC) is a rare cancer that arises within the jaws, often linked to odontogenic cysts or tumors. Its prevalence is about 1-2.5% of all odontogenic tumors and presents a diagnostic challenge due to its similarity to other jaw lesions. A 46-year-old woman complained of persistent pain in the left back region of the lower jaw, numbness over the left side of the lower lip, and reduced mouth opening. The doctor revised the initial diagnosis of periapical infection due to ongoing symptoms and a non-healing socket. Radiological imaging revealed an osteolytic lesion in the left ramus of the mandible, prompting further investigation. A biopsy confirmed the diagnosis of IOSCC following histopathological examination after segmental mandibulectomy. The final diagnosis was primary intraosseous well-differentiated squamous cell carcinoma of the left mandible. PIOSCC, even though it is uncommon, should be included in the list of possible diagnoses for jaw problems, especially those that have unclear, bone-destroying X-ray features. Symptoms such as pain, swelling, and sensory disturbances, along with radiologic findings, may suggest a malignant odontogenic tumor. Histological evaluation is crucial for differentiation from other odontogenic tumors, including ameloblastic carcinoma. Radical surgery, often combined with neck dissection, is the management of choice. Postoperative radiotherapy or chemotherapy may be considered, though their role remains unclear. The five-year survival rate with PIOSCC ranges from 30% to 46%, indicating a typically dismal prognosis. PIOSCC is an uncommon, aggressive tumor with a poor prognosis. Early diagnosis and accurate histopathological examination are essential to differentiate it from other odontogenic carcinomas and improve patient outcomes.