Abstract：
Spindle cell lipoma (SCL) is a rare form of lipoma, typically occurring as a mass in the back, shoulder or posterior neck of adult males. Most cases present little diagnostic difficulty on fine needle aspiration (FNA), but can be problematic when the SCL is in an unusual location. The authors report a case in the parotid gland in a 75-year-old man. FNA was paucicellular and showed loose collections of spindle cells with mild to moderate atypia, admixed with ropy collagen fibers on a myxoid background. The nuclei showed occasional angulation, interpreted on FNA as suspicious for myoepithelial tumor or low-grade sarcoma. The subsequent excisional specimen was diagnosed as SCL. On retrospective review of the FNA, an additional finding was recognized: \'naked\' nuclei with intranuclear lipid vacuoles and positive immunostaining for S100 protein, consistent with Lochkern cells of mature adipocytes. This case highlights the challenges of diagnosing SCL on cytology when no fat-containing cells are apparent on the smear, and stresses the significance of Lochkern cells as a clue for diagnosis.
摘要：
梭形细胞脂肪瘤（SCL）是一种罕见的脂肪瘤，通常发生在背部的肿块，成年男性的肩或后颈。大多数病例在细针穿刺（FNA）上几乎没有诊断困难，但是当SCL处于不寻常的位置时可能会有问题。作者报告了一名75岁男性的腮腺病例。FNA是无细胞的，显示梭形细胞的松散集合，具有轻度至中度的异型性，与黏液样背景上的粘胶原纤维混合。细胞核偶尔出现成角，在FNA上解释为怀疑肌上皮肿瘤或低度肉瘤。随后的切除标本被诊断为SCL。在FNA的回顾性审查中，另一个发现被确认：核内脂质液泡和S100蛋白阳性免疫染色的裸露核，与成熟脂肪细胞的Lochkern细胞一致。该病例突出了在涂片上没有明显的含脂肪细胞时在细胞学上诊断SCL的挑战，并强调Lochkern细胞作为诊断线索的重要性。
