Crystallographic Identifications of Calcium Deposits 161 



These calcifications were composed of calcium pyrophosphate, but curious intra- 

 osseous calcareous deposits in the metatarsal bones were identified as apatite. 



Discussion and conclusions 



We can only interpret the present findings within the limits permitted by the 

 techniques employed. However, this preliminary study has led to certain conclusions. 



1. Among the well-known pathological tissue calcifications, a great number are 

 apatite deposits. Of particular interest were those found in the following conditions: 

 calcinosis (circumscripta, universalis, milk-alkali syndrome); atheromatous plaques; 

 constrictive pericarditis or calcification of meninges; intra-osseous calcareous deposits 

 in an osteochondroma or a chronic bone infarct (in the latter this well-known fact 

 corresponded to the "apatite membrane"). In addition to histological data, the pres- 

 ence of apatite in the calcification of the shoulder's rotator cuff (so-called peri- 

 tendinitis calcarea) is another means of distinguishing it from that of chondro- 

 calcinosis articularis. 



2. In calcareous deposits of tuberculous or parasitic origin whitlockite and apatite 

 are present; this substantiates the previous observations of Brandenberger and 

 ScHiNZ (1945). The amount of the former is seemingly related to the rate of in- 

 flammatory activity of the process. In some rare instances, we find only apatite in 

 old cases. 



3. Chondrocalcinosis articularis is characterized by calcium pyrophosphate 

 dlhydrate deposits in articular structures, including the fibrocartilage of the menisci, 

 of the intervertebral discs or of the symphysis pubis. In eight cases of primary 

 chondrocalcinosis, asymptomatic or with clinical signs of polyarthrosis, we have 

 confirmed the findings of Kohn et al. (1962) and Bundens et al. (1965) in cases with 

 the clinical picture of "pseudogout". Similar observations were made in two cases of 

 chondrocalcinosis which were accompanied by diagnosed diseases. One of these was 

 primary hyperparathyroidism in which the cartilaginous lesions were histologically 

 similar to those described by Bywaters et al. (1963). The other was accompanied by 

 a uratic gout secondary to polycythemia vera. 



All these cases were characterized by the fact that the extra-articular calcifications 

 examined consisted of apatite. If this point were confirmed with visceral calcifica- 

 tions as in nephrocalcinosis, this would imply that calcium pyrophosphate deposits 

 do not correspond to a disease per se but are a common denominator in articular 

 tissue, depending on different etiological conditions. In primary chondrocalcinosis 

 these deposits are related to a condition of unknown origin but seemingly associated 

 with a genetic factor (Valsik et al., 1963); sometimes they are accompanied by a 

 metabolic disturbance like hyperparathyroidism, hemochromatosis (Delbarre, 1964; 

 DE Seze et al., 1964) or even gout. The possibility of an association between gout and 

 VON Recklinghausen's disease has been suggested (Bywaters et al., 1963; Vix, 

 1964). However, in our case of gout there was neither clinical nor pathological 

 evidence of hyperparathyroidism. We did not have the opportunity to examine 

 visceral calcifications of such origin with X-ray diffraction; nevertheless a single 

 examination with the polarizing microscope of nephrocalcinosis in von Reckling- 

 hausen's disease showed no crystals of the calcium pyrophosphate type. This ob- 



3'''' Europ. Symp. on Cal. Tissues 11 



