Pure Intramuscular Osteolipoma
A 51-year-old female presented with a 5-year history of a painless, progressively enlarging mass on the posterior neck. She reported neck stiffness without associated neurological symptoms. Physical examination revealed a soft, non-tender, uniform mass without surface abnormalities. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a circumscribed mass involving the posterior neck muscles in the midline between the C2 and C6 spinous processes with a large calcified component (). The ovoid mass was measured 4 cm in width, 6 cm in length, and 3 cm in height, without infiltration of the cervical spine. Subsequently, the patient underwent a whole body bone scan, which revealed an amorphous calcification of the posterior neck without metastasis ().\nWe performed tumor resection under general anaesthesia. The mass had a well-demarcated margin and the outer wall was very firm without adhesion to ligaments or paravertebral muscles. Gross examination revealed a well-circumscribed mass composed of adipose and bony tissue, with red bone marrow visible on the cut surface (). Histological study showed a lipomatous lesion with large foci of osseous metaplasia at the periphery of the mass; the bony portion was surrounded by mature adipose tissue (). Microscopic examination of the red bone marrow showed a meshwork of bone trabeculae and hematopoietic marrow elements ().\nThe patient was diagnosed with an intramuscular osteolipoma of the posterior neck and no recurrence was observed at the 6-month follow-up.