Spindle cell lipoma showing biphasic pattern--a case report.

This is a case report of a rare spindle cell lipoma (SCL) showing an unusual biphasic pattern with radiological findings and histological features. SCL is most common in men between the ages of 45 and 65 and it is reported that the tumor has a tendency to occur in the posterior neck area. This case was a 75-year old man with a 7 x 5 cm subcutaneous tumor in the posterior neck. Magnetic resonance imaging (MRI) examination demonstrated an unusual biphasic pattern. The signal intensities on T1 and T2 weighted images of the outer layer of the mass were high, and were suppressed on fat suppression views and showed no enhancement after gadolinium (Gd) injection. There was a low signal intensity area of 15 mm in diameter on both T1 and T2 weighted images, in the central part of the mass. This area was well enhanced with the Gd compound. Also macroscopically it could be seen that the excised tumor consisted of two different tissue components. Microscopically, the outer yellowish portion was mainly composed of mature adipose tissue. The inner whitish fibrous portion contained a mixture of small and uniform spindle-shaped cells, collagen fibers, and scattered mature adipose cells. No malignancy was observed. The diagnosis of spindle cell lipoma was made. No recurrence was seen seven months after marginal excision.