Primary intraosseous squamous cell carcinoma arising in odontogenic cysts: A report of five cases and a review of the literature

Abstract

Primary intraosseous carcinoma (PIOC) is rare entity with an estimated incidence of 0.01-0.02% of all oral cancer. To date, 133 PIOC cases have been reported with most occurring in the setting of periapical/residual cysts. Distinc- tion from carcinomas arising from the oral or antral mucosa may be difficult, especially when the cortical plates have been destroyed. Therefore, signs of oral ulceration preclude the diagnosis of PIOC. Identification of a benign cystic structure exhibiting transition to a squamous cell carcinoma may be of help in establishing the diagnosis and etiology of the tumor. The aim of our study was to evaluate the cases of only primary intraosseous squamous cell carcinomas arising in odontogenic cysts diagnosed in the Oral Pathology Laboratory at New York Presbyterian Queens between 1995-2019 with the goal of adding valuable information to the literature for this uncommon en- tity. Five cases of PIOC were identified. For each case the histology, demographics, radiographic descriptions and radiographs when possible were reviewed. In all cases, transition from a cystic structure to infiltrating carcinoma was identified. In no case did the overlying surface mucosa exhibit dysplastic changes or transition to carcinoma. Four cases occurred in the maxilla and one in the mandible. The average age of patients in this study was 67.6 years with a range of 37 to 81. Three patients were males and two were female. Three cases presented as ill-defined radiolucencies and one was described as a cystic expansion. Two PIOCs arose in the setting of a periapical cyst, one in the setting of a residual cyst and one in the setting of a dentigerous cyst. Two cases had associated bone loss. While uncommon, the possibility of carcinoma arising in what appears clinically to be a cyst, supports the need to submit all tissue for microscopic examination.