Primary intraosseous oral squamous cell carcinoma (PIOSCC) of the jaws: two clinical cases

OBJECTIVES The aim of this paper is to provide an overall picture of primary intraosseous squamous cell carcinoma (PIOSCC) from a clinical and radiographical point of view, analyzing the diagnostic and therapeutic process through the description of two clinical cases. MATERIALS AND METHODS PubMed, Google Scholar, Scopus, and Embase databases were consulted, and the key words "primary intraosseous squamous cell carcinoma," "intraosseous carcinoma of the jaws," and "odontogenic keratocyst" were used for the research. Case reports, case series, and systematic reviews of the literature were included. Moreover, we also discuss two clinical cases referred to the department of the authors (ASST Santi Paolo Carlo - S.C. Odontostomatology II, Milan, Italy) for a mandibular swelling with no alterations affecting the overlying mucosa. RESULTS Considering the rarity of PIOSCC, in both cases it was necessary to collect complete medical history, add radiographic data to the clinical examination and perform an incisional biopsy in order to reach a definitive diagnosis. The surgical removal of the lesion, followed by adjuvant radiotherapy (RT), was the first-choice treatment for both patients. CONCLUSIONS Primary intraosseous squamous cell carcinoma (PIOSCC) is a rare malignant neoplasm that lacks an initial connection with the oral mucosa. It can arise de novo from remnants of odontogenic epithelium or from the epithelial layer of odontogenic cysts or keratocysts. More common in the lower jaw (79%) rather than in the maxilla (21%), its preferential site is the posterior region of the mandible (retromolar and ramus areas). It preferentially affects adult males, with a mean age of 57.3 years and a range that can vary from 5 to 89 years. The prognosis of primary intraosseous squamous cell carcinoma is poor: in fact, the local recurrence rate is around 20% and the 5-year survival rate is between 30 and 40%. The recommended treatment is the surgical resection of the lesion, together with elective neck dissection. Adjuvant radiotherapy and chemotherapy may be evaluated according to the feature of the clinical case. CLINICAL SIGNIFICANCE Due to the lack of pathognomonic clinical signs, the diagnosis of PIOSCC still remains a complex process. The clinical and radiographic appearance, especially in the early stages and when the tumor is small in size, may be almost entirely superimposable to the clinical features of odontogenic cysts or other benign neoplasms. The rarity of this malignancy and the presence of nonspecific signs and symptoms often lead to a wide diagnostic delay, which can range from few weeks up to 18 months.