This video provides a pathological examination of a cartilage lesion identified as synovial chondromatosis. The key microscopic features are discussed, focusing on the presence of multiple, irregular islands of hyaline cartilage located within the soft tissue immediately adjacent to a synovial space (such as a joint space or tendon sheath). Diagnostic criteria highlighted include the tendency of the chondrocytes to form distinct clustered groups (cloning) and variable calcification, which increases with the chronicity of the lesion, allowing visibility on X-rays. The presenter differentiates synovial chondromatosis from soft tissue chondroma, noting the latter is typically a single, solitary nodule.
Synovial Chondromatosis: Pathology and Diagnosis
0:03 Lesion Description: The sample shows a cartilage lesion consisting of multiple, irregular nodules ("islands") of varying sizes.
0:15 Location is Critical: The cartilage is located in the soft tissue, not the bone, directly adjacent to a synovial-lined space (e.g., a joint space or tendon sheath).
0:26 Diagnosis: The overall presentation is characteristic of Synovial Chondromatosis, described as a metaplastic process where multiple islands of cartilage form near the synovial lining.
0:55 Microscopic Feature β Hyaline Cartilage: The islands consist of hyaline cartilage.
1:00 Key Diagnostic Feature (Clustering): The chondrocytes within the islands tend to be clustered together in small groups, a pattern often referred to as "cloning" (seen well at 1:20 and 2:41).
1:30 Calcification: Lesions exhibit variable amounts of calcification (calcium deposition). The calcification allows the lesion to be seen on X-rays, particularly in older/more chronic cases.
2:04 Differential Diagnosis: The main differential is a chondroma of soft tissue. Synovial chondromatosis is distinguished by having multiple nodules and being adjacent to a synovial space, whereas a soft tissue chondroma is usually a single/solitary nodule.
2:36 Clinical Note: The cartilage islands can break loose and enter the joint space, forming "loose bodies."