Mesenchymal Chondrosarcoma Mimicking Apical Periodontitis Mike Reis Bueno, DDS, MSc, PhD,* Artur Aburad De Carvalhosa, DDS, MSc, PhD, † Paulo Henrique De Souza Castro, DDS, ‡ Kenper Carlos Pereira, DDS, ‡ Fabiano Tonaco Borges, DDS, MSc, § and Carlos Estrela, DDS, MSc, PhD  Abstract This report describes the case of a patient with mes- enchymal chondrosarcoma in the region of tooth #18 that mimicked apical periodontitis. Forty-five days after endodontic treatment, gingival swelling and intense pain were observed. The endodontist suspected a fur- cation lesion, and the treatment option that the patient chose was extraction of the tooth. Seven days after suture removal, a rapidly growing swelling was seen in the region. The patient was referred to an oral and maxillofacial surgeon, who recommended an incisional biopsy after evaluating imaging and clinical findings. Microscopic examination confirmed the diagnosis of mesenchymal chondrosarcoma. The patient underwent hemimandibulectomy with wide surgical margins. This clinical case draws attention to the fact that endodontic lesions should be carefully evaluated because malig- nant tumors such as mesenchymal chondrosarcoma might mimic apical periodontitis. (J Endod 2008;34: 1415–1419) Key Words Apical periodontitis, chondrosarcoma, differential diag- nosis, malignant tumor, mesenchymal chondrosarcoma A pical periodontitis is frequently associated with outcomes of root canal infection. Some periapical lesions of nonendodontic origin might mimic apical periodontitis of endodontic origin (1–4). Such lesions might be misdiagnosed at their early stages because a malignant tumor might not be suspected (1). Such clinical cases, mainly those with expansion of the lingual or buccal cortical plate, require careful evaluation and a precise differential diagnosis, particularly because the accuracy and sensitivity of routine single radio- graphs are not enough for a diagnosis (5). Other imaging studies might also provide useful information at this stage, but a definitive diagnosis can only be made after histopathologic examinations. Chondrosarcomas are malignant tumors characterized by the formation of carti- lage. They account for 10% of all primary tumors of the skeleton, but less than 1% of all chondrosarcomas arise in the head or neck (6). This report describes a case of mesenchymal chondrosarcoma that mimicked apical periodontitis. Case Report A 28-year-old female patient was referred to an endodontist as a result of pain in tooth #18. She received root canal treatment because of a radiographic and clinical diagnosis of primary endodontic infection associated with apical periodontitis (Fig. 1). About 45 days after endodontic treatment, gingival swelling and intense pain were observed. The endodontist believed that symptoms were due to a furcation lesion, and the treatment option chosen by the patient was tooth extraction. Seven days after suture removal, a rapidly growing swelling was observed in the region. The patient was re- ferred to an oral and maxillofacial surgeon. Panoramic and periapical radiographs were taken, and intense growth of the lesion compromised biting (Fig. 2). The patient believed that the pain was caused by occlusion trauma. Imaging studies (computed tomography, scintigraphy) showed a destructive radiolucent area (Figs. 3 and 4). From the *University of Cuiabá, Cuiabá, MT; † Federal University of Mato Grosso, Cuiabá, MT; ‡ Specialist in Oromax- illofacial Surgery, Cuiabá, MT; § Mato Grosso School of Public Health, Cuiabá, MT; and  Federal University of Goiás, Goiânia, GO, Brazil. Address requests for reprints to Carlos Estrela, PhD, Pro- fessor, Centro de Ensino e Pesquisa Odontológica do Brasil (CEPOBRAS), Rua C-245, Quadra 546, Lote 9, Jardim América, CEP: 74.290-200, Goiânia, GO, Brazil. E-mail address: estrela3@ terra.com.br. 0099-2399/$0 - see front matter Copyright © 2008 American Association of Endodontists. doi:10.1016/j.joen.2008.08.016 Figure 1. Periapical radiograph of tooth #18 shows root canal filling and apical periodontitis. Radiolucency in furcation area is suggestive of a lesion. Case Report/Clinical Techniques JOE — Volume 34, Number 11, November 2008 Mesenchymal Chondrosarcoma Mimicking Apical Periodontitis 1415