IDIOPATHIC FAMILIAL CHONDROCALCINOSIS DUE TO APATITE CRYSTAL DEPOSITION

Idiopathic familial chondrocalcinosis was found in 5 members of a family. The clinical features of the disease were morning stiffness, pain and limitation of motion of the dorsolumbar spine in 4 of the 5 members, associated with arthritis of the small joints of the hands in 3, shoulder periarthritis in 2 and costal cartilage pain in 1. Radiologically, 4 of the 5 patients had multiple intervertebral disk calcifications, mainly located at the nucleus pulposus area. Three also had periarticular calcific deposits, associated with costal cartilage calcifications and degenerative changes in the small joints of the hands in 2. None of these cases showed cartilage calcification in the knees, pubic symphysis or triangular ligament of carpus. In the propositus, optical microscopy of a specimen of the 2nd 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 capsule. X-ray diffraction studies, energy dispersive analysis and IR spectrophotometry of a costal cartilage sample obtained by open biopsy demonstrated the presence of carbonate calcium hydroxylapatite. No relation was found between HLA antigens, loci A, B and C, and this syndrome due to calcium hydroxylapatite crystal deposition.