The chondroid metaplasia should be distinguished from cartilaginous choristoma that is almost entirely formed by mature hyaline cartilage [8,9] and also, it should be included as differential histopatological diagnosis. The chondroma or soft-tissue chondroma are rare and only few cases have been reported in the oral cavity [1,10,11]. Lesions are formed by lobules of mature (chondrocytes) or immature (chondroblasts) hyaline cartilage with varying degrees of cellularity [12]. Like normal chondrocytes, the cells of chondroid tissue are positive for Vimentin and S100 protein, in adition, biochemically this was characterized by a gradual increase in the mucopolysaccharide content towards the area of chondroid metaplasia. In the present case, mature hyaline cartilage was absent and showed multiple well circumscribed lobules of chondroid material, of varying in shape and size. The chondroid material was surrounded by fibrous septa and was intermixed with dense fibrous connective stroma, covered by epithelium. Further, the tissue was found to be positive for immunohistochemical markers, alcian blue and S100 protein.
Cartilaginous metaplasia involving the atrioventricular (AV) node is an uncommon entity that may cause sudden cardiac death secondary to dysrhythmias. We report 2 autopsy cases of full-term male newborns: 1 stillborn and 1 live-born, with antemortem bradycardia who died in the peripartum period. An examination of the cardiac conduction system in both cases demonstrated extensive cartilaginous metaplasia of the central fibrous body and involvement of the AV node and bundle of His. The cases highlight the recognition of cardiac conduction system anomalies as a cause of sudden perinatal death. In cases of perinatal death with preceding arrhythmia, postmortem sections of the cardiac conduction system are recommended to examine for cardiac conduction system anomaly.
