Abstract. Primary intraosseous squamous cell carcinoma (PIOSCC) is a rare malignant central jaw tumor derived from odontogenic epithelial remnants. PIOSCC predominantly affects the mandible, although both jawbones may be involved. This case report describes a PIOSCC type 2 of the maxilla in a 37-year-old man, treated by partial maxillectomy. Histopathologically, the tumor was diagnosed as PIOSCC derived from an odontogenic cyst. Postoperatively, the patient has been followed up for 53 months, with no recurrence of the disease. We herein describe the clinical details, treatment results and histopathological characteristics of a rare case of PIOSCC derived from a maxillary odontogenic cyst with reference to the relevant literature.
IntroductionPrimary intraosseous squamous cell carcinoma (PIOSCC) is a central jaw carcinoma derived from odontogenic epithelial remnants. PIOSCC is defined as a SCC arising within the jaw, and it has no initial connection with the oral mucosa. This tumor was first described by Loos (1) in 1913 as a central epidermoid carcinoma of the jaw. Willis (2) renamed the tumor as intraalveolar epidermoid carcinoma in 1948. In 1972, Pindborg et al (3) suggested the term primary intraosseous carcinoma (PIOC) and classified the lesion as an odontogenic carcinoma. Subsequently, the classification of odontogenic carcinomas was modified in several studies (4-6). In 2005, Eversole et al (7) introduced the term 'primary intraosseous SCC' (PIOSCC) and further categorized this entity into 3 types: Type 1 for solid tumors, type 2 for carcinomas arising from odontogenic cysts and type 3 for carcinomas associated with odontogenic tumors.In PIOSCC type 2, an SCC results from malignant transformation of an odontogenic cyst. To establish the presence of such malignant transformation, certain diagnostic criteria must be fulfilled (8). The estimated incidence of PIOSCC type 2 has been shown to range from 0.1 to 1.8% of all oral cancers (9-12). Bodner et al analyzed 116 reported cases of PIOSCC arising in an odontogenic cyst and found that the tumors predominantly affected the mandible, whereas the maxilla was affected in 21% of the cases (13).We herein report a case of PIOSCC derived from a maxillary odontogenic cyst. We have also reviewed the literature for cases of PIOSCC arising from maxillary cysts, including keratocystic odontogenic tumors, with respect to the diagnosis, prognosis and treatment of these tumors. Written informed consent was obtained from the patient for the publication of his case details.
Case reportIn August, 2010, a 37-year-old Japanese man visited the Department of Oral Surgery in another hospital, with a 4-month history of a painful swelling in the left maxillary gingiva. Following clinical examination, the patient was diagnosed with apical periodontitis and antibiotics were prescribed; however, no improvement was noted. In October, 2010, the patient presented with a fistula in the left maxillary gingiva. A computed tomography (CT) scan revealed an area of bone resorption in the lateral ...