Calcinosis Circumscripta. A Case Report with X-ray Diffraction Studies.

A small subcutaneous mass located on the right foreleg of a 3 months old Brittany spaniel was observed to progressively enlarge over a 2 month period. The lesion which had not affected locomotion was removed at 5 months of age and was diagnosed as calcinosis circumscripta. The chalk-like material contained in the lesion was studied by x-ray diffraction and from the crystallographic view point, the structure of this growth was not different from that of normal or abnormal calcification. As there is no agreement on the exact chemical arrangement of bone salts (13), the observed x-ray powder diffraction pattern may be taken as that corresponding to a calcium phosphate hydrated (14), a calcium phosphate of apatite structure (15), a pseudo-apatite (16), or a hydroxy apatite (17).