%0 Journal Article %T Malignant Transformation of an Odontogenic Cyst in a Period of 10 Years %A Juliane Pir¨¢gine Ara¨²jo %A Luiz Paulo Kowalski %A M£¿nica L¨²cia Rodrigues %A Oslei Paes de Almeida %A Clovis Antonio Lopes Pinto %A Fabio Abreu Alves %J Case Reports in Dentistry %D 2014 %I Hindawi Publishing Corporation %R 10.1155/2014/762969 %X Primary intraosseous carcinoma of the jaws (PIOSCC) might arise from odontogenic epithelium, more commonly from a previous odontogenic cyst. The aim of this case is to illustrate that the clinician should consider that an apparent benign dentigerous cyst can suffer malignant transformation and that all material removed from a patient must be evaluated histologically. A 44-year-old man presented in a routine periapical X-ray an impacted lower left third molar with radiolucency over its crown. Ten years later, the patient complained of pain in the same region and the tooth was extracted. After one month, the patient still complained of pain and suffered a fracture of the mandible. A biopsy was performed and carcinoma was diagnosed. The patient was treated surgically with adjuvant radio- and chemotherapy and after 8 years, he is well without signs of recurrences. This report describes a central mandibular carcinoma probably developed from a previous dentigerous cyst. 1. Introduction Primary intraosseous squamous cell carcinomas of the jaws (PIOSCC) are aggressive malignancies mainly derived from odontogenic epithelium [1]. These carcinomas can be aggressive, involving large areas of the jaws, but the features are usually nonspecific and biopsy confirms the diagnosis [2, 3]. The two-to-six-year survival rate is approximately 53% and local recurrence has been the major problem in patients not treated with radical excision [1]. Malignant transformation of odontogenic cysts is estimated to be between 0.13% and 2%, with most of the cases involving the mandible [3]. In addition, the aim of this report was to describe a case of an intraosseous oral squamous cell carcinoma, probably derived from an odontogenic cyst. 2. Case Report A 44-year-old man was referred to our cancer center for treatment of a jaw tumor. The medical history revealed that in 1994 the patient underwent a periapical X-ray of an impacted lower left third molar, showing radiolucency over the crown interpreted as dentigerous cyst (Figure 1(a)). There were no symptoms and the patient and his dentist decided just to follow up. After 11 years the patient presented pain in the region and both tooth and lesion were removed and discarded. After 15 days (Figures 1(b) and 1(c)), the patient continued to present pain and a panoramic X-ray showed a local tooth extraction with no signs of malignant lesion. A biopsy was performed and the diagnosis was of squamous cell carcinoma (SCC). Figure 1: (a) Periapical X-ray showing a radiolucency surrounding the crown of the left third molar suggestive of dentigerous %U http://www.hindawi.com/journals/crid/2014/762969/