Spindle cell lipoma in the pterygomandibular space: A case report

Spindle cell lipoma (SCL) is a subtype of lipoma classified by Enzinger et al. in 1975. It is a benign tumor commonly found in the subcutaneous tissue of the shoulder, back, and posterior neck in middle-aged men. This report describes a rare case of low-fat type SCL in the pterygomandibular space. A 33-year-old man was referred to the department for further examination and treatment of a radiolucent area of the left mandibular ramus incidentally detected on a panoramic radiograph taken by a general dentist. Computed tomography and magnetic resonance imaging showed a 50 mm mass with apparent continuity with the inferior alveolar neurovascular bundle in the pterygomandibular space. An incisional biopsy prompted a provisional diagnosis of neurofibroma, and the whole tumor was excised under general anesthesia. Histopathologically, the tumor was found to consist of spindle-shaped cells, adipocytes, and collagen fibers, resulting in a final diagnosis of SCL. There has been no evidence of recurrence more than 5 years postoperatively. • Spindle cell lipoma is present in the pterygomandibular space. • SCL has no typical imaging findings because it exhibits variegated structural components. • SCL is characterized by a mixture of mature adipocytes and fibroblast-like spindle cells, the proliferation of interstitial collagen fibers and elastic fibers, and myxoid stroma and mast cells. • The constituent and histological type variations also complicate this diagnosis • Immunostaining with CD34 is useful for detecting fibroblast-like spindle cells