158 R. Lagier, C. a. Baud, M. Buchs 



Crystallographic Identification of Calcium Deposits 



as Regards their Pathological Nature, with Special Reference to 



Chondrocalcinosis 



R. Lagier, C. A. Baud, M. Buchs 



Instltut de Pathologic et Institut de Morphologic, Universite dc Geneve, Geneve, Suisse 



In a paper published in 1962, Kohn et al. showed that the "Pseudogout Syn- 

 drome" of chondrocalcinosis articularis was accompanied by the presence in synovial 

 fluid of a form of calcium pyrophosphate crystals. By their size, these crystals are 

 comparable with those of sodium urate and therefore are presumably able to induce 

 articular attacks. Moreover, they can produce two types of joint disturbances: a synov- 

 ial inflammatory reaction that may present a picture similar to that of rheumatoid 

 arthritis; a cartilage deterioration creating the morphological condition of osteo- 

 arthrosis, which is found occasionally in several joints. However, these deposits may 

 be observed without clinical signs and found in routine radiographical or post-mortem 

 examination. It is also interesting to note that the histological pictures are in several 

 ways similar to those of gout, in cartilage as well as in reacting synovial membrane, 

 where microtophi can sometimes be observed (Lagier, to be published). 



The purpose of this paper is to study these deposits of chondrocalcinosis and 

 compare them with other tissue calcifications. 



Material and techniques 



This study is limited to tissue calcifications, excluding mineral deposits in cavities 

 or canals. Tests were performed on 108 samples from 42 cases, collected by means of 

 biopsy or from post-mortem material; each sample was ground and studied by the 

 X-ray diffraction method for crystallographic identification. 



Results 



Our results are presented in three tables, corresponding to three groups of findings. 

 We have indicated the nature of the different samples and their number, and also 

 given the number of cases (i.e., of subjects) from whom the samples were collected. 

 In some instances specimens of a different nature were obtained from the same case. 



Three types of crystals were observed; apatite, whitlockite and calcium pyro- 

 phosphate dihydrate. 



The first group includes deposits with apatite only and corresponds to a broad 

 spectrum of pathological calcification (Table 1). 



The second group is represented by deposits with whitlockite and apatite 

 (Table 2). They were found predominantly in lesions of tuberculous or hydatid 

 disease. In some of these deposits a tuberculous or parasitic origin was only suspected, 

 though the probability was great; here the situations and conditions were different 

 from those of the first group. The relative amount of whitlockite, as compared to 

 that of apatite, was apparently in direct relationship to the degree of inflammatory 

 activity. In some extreme conditions only whitlockite or apatite was observed, the 

 latter occurring in old and stabilized processes. 



