A mildly painful wrist mass

Abstract

Familial tumoral calcinosis (FTC) is a rare autosomal recessive disease characterized by progressive deposition of periarticular calcifications [1, 2]. It can be divided into hyperphosphatemic and normophosphatemic types depending on the serum phosphate level [3]. In the hyperphosphatemic type, the GALNT3 gene, which codes for a glycosyltransferase and FGF23 gene that codes for a phosphaturic protein, have been identified as the cause of phosphate dysregulation [3, 4]. In the less common normophosphatemic type, SAMD9 gene mutation causes dysregulation of endothelial cell and fibroblast function. A positive family history is present in 30–40 % of patients while the rest are sporadic [4]. FTC is most common in patients of African decent [1]. Typically, patients present in the first two decades of life with solitary or multiple painless periarticular “tumors” that reduce range of motion in the involved joints [2]. The periarticular swelling is painless unless there is nerve impingement. The overlying skin is usually intact. Occasionally, soft tissue ulceration with extrusion of chalky white material can be seen. Radiographically, lobulated, variably calcified, juxtaarticular masses in bursal distribution can be seen (Figs. 1, 2 and 3a). Extensor surfaces are commonly involved, with descending frequency of distribution at hip, elbow, shoulder, foot, and wrist. Less commonly, they happen in extraarticular regions without naturally occurring bursa including scalp, larynx, spine, and sacrum, where there is synovial metaplasia forming bursa-like structures in response to trauma [2, 5]. Sedimentation sign, which represents fluid–fluid levels caused by calcium layering, is classical [6] (Fig. 3b,c). Although the sedimentation sign is usually best appreciated in cross-sectional imaging, sometimes it can be evident only in ultrasound [7]. On CT imaging, lobulated cystic calcification that communicates with the bursa can be demonstrated. The appearance of homogeneity suggests a reduced metabolic activity and lower likelihood of growth [8, 9]. There should not be any erosion or destruction of adjacent bones. On MRI, FTC has a variegated appearance [2, 10]. In T1W The case presentation can be found at doi:10.1007/s00256-013-1710-8.