Spindle cell lipoma developing in the parotid gland: A case report

Abstract Spindle cell lipoma (SCL) is one of the uncommon variants of benign lipoma. It often shows difficulty in diagnosis because it has clinically and histopathologically similar findings with pleomorphic adenoma (PA) and Warthin tumor, and its MR images show relatively lots of variants. In this case report, a 64-year-old male, who was finally diagnosed as SCL is reported. The process to the final diagnosis was challenging due to untypical MR images and the existence of spindle cells. The clinical examination of the patient showed a soft and painless swelling in the preauricular area with approximately 2 cm in diameter. The MR images showed a 2 cm diameter-circular lesion with cleared margin and internal heterogenous structure, which consisted of hyperintensity in the short-tau inversion recovery images, hypointensity in T1-weighted images and moderate hyperintensity with internal heterogenous structure in T2-weighted images. Under the clinical diagnosis of pleomorphic adenoma, surgical resection was performed. Fibrous capsule admixed with mature adipocyte and basophilic mucoid substances were observed histopathologically. Immunohistochemical examinations revealed that spindle cells were positive for CD34, and Bcl-2 adipocytes were positive for S-100. On the basis of these findings, the specimen was finally diagnosed as SCL of the parotid gland. The divergence between clinical and pathological diagnosis is highly influenced by MR images, and this case report could append a new insight into the MR images of SCL.