3.Discussion
Xanthomatosis of the skin is a group of diseases characterized by yellow patches, papules, or nodules, accompanied by increased lipids and other organ abnormalities. 8 Due to the accumulation of lipid-containing cells in the skin dermis, yellow nodular lesions often form on the skin surface. 9 The rash forms and distribution of this disease vary, and there are mainly 4 types: nodular, flat, rash and tendinous.10 This disease can be associated with abnormal lipid metabolism. Some cases have familial or systemic lesions. For example, lipid deposition in the cardiovascular system that can produce arteriosclerosis and embolism of small vessels. 11,12
There were few literature reports about ultrasonic findings of multiple tubercular xanthomas on bilateral buttocks with hypercholesterolemia. 13,14And most of them is all about ultrasonic findings of achilles tendon xanthoma.15,16However, this case report is about ultrasonic characteristic manifestations of multiple tubercular xanthomas on bilateral buttocks with hypercholesterolemia. Ultrasound can find the size, depth, layer of skin involved and blood supply of lesion, providing vital help for surgical options.
More importantly, Sonographic appearance had certain characteristics in this case. There were several hyperechoic masses in the skin dermis of bilateral buttocks, and the biggest was on the left buttock, with clear boundary and irregular shape. Abundant blood flow signals could be detected within the masses. Low-velocity, low-obstruction arterial and low-velocity venous blood flow spectra were detected, which might be a characteristic performance in diagnosing this rare case. Appearance of blood signal may indicate foam cell activity. Further study with a large sample size is needed to confirm it. Moreover, the uneven internal echo was meshed, which might be related to the nodular distribution of foam cells. Therefore, the ultrasonic characteristic findings contained uneven meshed internal echo and abundant blood flow signals within the masses, with low-obstruction arterial and low-velocity venous blood flow spectra. They can help to differentiate xanthomas from other diseases such as skin keloid in which blood flow signals cannot be detected. Due to the rarity of xanthomas at this site, the experience of ultrasonic examination still needs to be accumulated in future case study.