Metabolic Diseases and Crystal Induced Arthropathies Technic of Non-Staining Histologic Sections - A Comparative Study of Standard Stains and Histochemical Reactions

Arthropathy induced by monosodium salt of uric acid [C 5 H 4 N 4 O 3 ] (MSU) (gout), by calcium pyrophosphate dihy- drate [Ca 2 P 2 O 7 .2H 2 O] (CPPD) crystals (chondrocalcinosis, pseudogout, pyrophosphate arthropathy) and arthropathy induced by hydroxyapatite [Ca 5 (PO 4 ) 3 (OH)] (HA) crystals (apatite rheumatism, hydroxyapatite arthritis, calcifying te-nosynovitis, Milwaukee syndrome, calcific tendinitis, calcific periarthritis) are regarded as distinct clinical entities. The solubility of MSU, CPPD and HA crystals in conventional fixatives (aqueous formaldehyde solution), in alcohol, ace -tone, and xylene or in solutions of dyes vary. The crystals in of 105) tissue samples of 37 (78.72% of 47) patients; CPPD in 15 (60.00% of 25) tissue samples of 10 (62.50% of 16) patients. HA crystals were detected exclu sively with this method: in all tissue samples (in 19 of 19; 100.0%) of all patients (in 4 of 4; 100.0%), none with the traditional stains and reactions. The non-staining technique is a simple and very effective method to demonstrate crystal deposits in tissue samples. Handbooks of histologic methods and histochemistry do not mention this simple technique. In case of clinically or histologically suspected meta bolic or crystal-induced diseases it is advisable to analyze unstained tissue sections as well, supplemented with the traditional hematoxylin-eosin stained ones. This approach may also be useful in other crystal deposition induced diseases or identification of foreign bodies and refractile arte -facts.