Calcium crystal-associated diseases and miscellaneous crystals.

Calcium crystal-associated diseases are still a challenge in clinical and basic science. Advances in understanding crystal formation and dissolution and crystal participation in inflammation are reported here. Studies on different methods of identification are reviewed, emphasizing the need for accurate and reproducible ways to study and diagnose calcium crystal-associated diseases. Reports of uncommon presentations are also described, including a controlled study on calcification of the ligamenta flava of the spine and a study involving 19 years of clinical follow-up of families with hydroxyapatite chondrocalcinosis with spondyloepiphyseal dysplasia. Studies on miscellaneous crystals are few. Two recent reviews are described on cholesterol crystal embolization syndrome and cryocrystalglobulinemia.