Idiopathic familial chondrocalcinosis due to apatite crystal deposition.

Idiopathic familial chondrocalcinosis was found in five members of a family. The clinical features of the disease were morning stiffness, pain and limitation of motion of the dorsolumbar spine in four of the five members, associated with arthritis of the small joints of the hands in three, shoulder periarthritis in two and costal cartilage pain in one. Radiologically, four of the five patients had multiple intervertebral disk calcifications, mainly located at the nucleus pulposus area. Three of them also had periarticular calcific deposits, associated with costal cartilage calcifications and degenerative changes in the small joints of the hands in two. None of these cases showed cartilage calcification in the knees, public symphysis or triangular ligament of carpus. In the propositus, optical microscopy of a specimen of the second proximal interphalangeal joint obtained by open biopsy showed the presence of multiple calcified areas in the intercellular matrix and chondroid metaplasia with calcification of the matrix in the synovial membrane and capsule. X-ray diffraction studies, energy dispersive analysis, and infrared spectrophotometry of a costal cartilage sample obtained by open biopsy demonstrated the presence of carbonate calcium hydroxyapatite. In this study, no relation was found between HLA antigens, loci A, B and C, and this syndrome due to calcium hydroxyapatite crystal deposition.