Musculoskeletal ImagingXanthoma
a
tumour composed of lipid-filled histiocytes containing lipid material in the cytoplasm. These tumous can be classified into several types (Table 1).
Xanthoma, Table 1.
| Type | Manifestations |
|---|
| Eruptive xanthomas | Yellow papules containing triglycerides with surrounding erythema on the knees, buttocks, back and shoulders. |
| Tendinous xanthomas | Localized deposits in the tendons of the palm and dorsum of the hand, the patellar tendon, the Achilles tendon, the plantar aponeurosis, the peroneal tendons, around the elbow, and the fascia and periosteum overlying the lower tibia. |
| Tuberous xanthomas | Subcutaneous masses, which occur over extensor surfaces. |
| Subperiosteal and osseous xanthomas | Lipid deposits beneath the periosteum or that replace trabeculae, leading to osteolytic defects, erosion of the cortex and even ostennecrosis from vascular occlusion. |
| Xanthelasma | Xanthoma of the eyelids. |
A prominent manifestation of the hyperlipoproteinaemias is xanthomas in soft tissue, tendinous, subperiosteal and intraosseous locations. Tuberous and tendinous xanthomas produce nodular masses in soft tissue and tendons that rarely calcify; tendinous xanthomas are common in the fingers, heel, elbow and knee, at which sites they may erode subjacent bone. Subperiosteal xanthomas are associated with scalloping of the external cortical surface. Intramedullary deposition of lipids leads to lytic defects and pathologic fractures.
Ultrasonography, CT and MR imaging are favoured for the diagnosis of soft tissue xanthomas. The signal intensity of xanthomas on MR imaging varies. The tumours may be of persistent low to intermediate signal intensity on T1-weighted and T2-weighted spin-echo MR images and may show an inhomogeneous signal pattern. Focal areas of high signal intensity may occasionally be encountered on T2-weighted images, however. Some patients reveal a diffuse speckled pattern of signal intensity within a tendon.
The presence of numerous xanthomas is known as xanthomatosis.
DR