Hydroxyapatite crystal deposition forming para-articular multiple large masses: a case report and literature review.

Multiple para-articular large masses are a rare form of hydroxyapatite (HA) crystal deposition, thereby limiting the clinical and imaging recognition and the ability to optimize diagnostic tools. The imaging features of para-articular large mass caused by HA crystal deposition are not well described in the sonographic literature. In this report, we present the case of a uremia patient with long period of maintenance hemodialysis, who was complicated with HA crystals depositing on the para-articular of elbow, knee, and shoulder and forming multiple large masses. We reviewed the literature to explore the ideal methods to establish a diagnosis. In addition, we performed a characterization of the sonographic features of HA crystals. We have established methods which serve to distinguish HA crystal deposition from other crystal deposit conditions.