ATYPICAL SPINDLE CELL NEOPLASM OF THE JAW MIMICKING A BENIGN LESION—A RARE CASE REPORT

Abstract

Clinical Presentation Atypical spindle cell neoplasms are extremely rare lesions, especially in the jaws, and are well known for their aggressive behavior.1 We present the case of a 58-year-old male in whom this tumor was incidentally noted on routine dental examination. The tumor resembled a benign odontogenic lesion on computed tomography (CT) and magnetic resonance imaging (MRI). Because of its propensity for metastasis, positron emission tomography (PET)/CT was performed to rule out distant metastasis. Differential Diagnosis Correlating the innocuous clinical presentation with the radiographic appearance of well-defined nature of the lesion and its paracoronal position with respect to an impacted tooth, the differential diagnosis included dentigerous cyst, other odontogenic cyst, cystic ameloblastoma, and other benign odontogenic tumor. Because of the irregular margins, we assumed the lesion could have been secondarily infected. Diagnosis and Management Histopathologic examination revealed an atypical pleomorphic spindle cell neoplasm of indeterminate origin. The patient underwent segmental mandibulectomy with radical neck dissection. Follow-up PET/CT revealed mild fluoro-2-deoxy-D-glucose (FDG) avidity in the left intraparotid lymph nodes. This could be a reactive process or recurrent/second primary tumor. A close follow-up after 3 months was recommended. Discussion Undifferentiated spindle cell sarcomas are high-grade, aggressive soft tissue sarcomas with no specific line of differentiation. To our knowledge, fewer than 30 cases have been reported. This case would be of specific interest to oral and maxillofacial radiologists because of its resemblance to a benign odontogenic lesion on CT and MRI. In conclusion, this malignancy can mimic benign lesions, and this may have significant influence on formulating the treatment plan, favoring a more conservative approach. Atypical spindle cell neoplasms are extremely rare lesions, especially in the jaws, and are well known for their aggressive behavior.1 We present the case of a 58-year-old male in whom this tumor was incidentally noted on routine dental examination. The tumor resembled a benign odontogenic lesion on computed tomography (CT) and magnetic resonance imaging (MRI). Because of its propensity for metastasis, positron emission tomography (PET)/CT was performed to rule out distant metastasis. Correlating the innocuous clinical presentation with the radiographic appearance of well-defined nature of the lesion and its paracoronal position with respect to an impacted tooth, the differential diagnosis included dentigerous cyst, other odontogenic cyst, cystic ameloblastoma, and other benign odontogenic tumor. Because of the irregular margins, we assumed the lesion could have been secondarily infected. Histopathologic examination revealed an atypical pleomorphic spindle cell neoplasm of indeterminate origin. The patient underwent segmental mandibulectomy with radical neck dissection. Follow-up PET/CT revealed mild fluoro-2-deoxy-D-glucose (FDG) avidity in the left intraparotid lymph nodes. This could be a reactive process or recurrent/second primary tumor. A close follow-up after 3 months was recommended. Undifferentiated spindle cell sarcomas are high-grade, aggressive soft tissue sarcomas with no specific line of differentiation. To our knowledge, fewer than 30 cases have been reported. This case would be of specific interest to oral and maxillofacial radiologists because of its resemblance to a benign odontogenic lesion on CT and MRI. In conclusion, this malignancy can mimic benign lesions, and this may have significant influence on formulating the treatment plan, favoring a more conservative approach.