1. The literature on pigmented villonodular synovitis has been reviewed and a series of eighty additional cases is reported.

2. The condition usually presents either as a nodule in a finger or knee, or as a diffuse lesion in a knee. The lesions, although benign, sometimes erode or invade the tissue of adjacent bones.

3. Distinction from malignant synovioma can be made on the basis of the macroscopic appearance of the lesion at operation (relationship to joints or tendon sheaths: villonodular appearance: pigmentation), and by histological examination.

4. Treatment of the nodular form by excision is satisfactory but extensive synovectomy for diffuse lesions of the knee gives poor results.

5. The etiology of pigmented villonodular synovitis is unknown, but it appears to be a self-limiting process, possibly inflammatory in nature.

1. Radiographs of both shoulders were performed on 106 unselected necropsy subjects and those found to be abnormal were examined pathologically.

2. Radiological abnormalities were found in sixty-eight shoulders of thirty-eight subjects. Pathological examination showed rotator cuff tears and associated abnormalities in thirty-five of these, rheumatoid arthritis in one, a previous fracture in one, and one was not examined.

3. The criteria for radiological diagnosis of rotator cuff tears are examined and discussed.

4. The radiological changes give little indication of the severity of the tears or associated abnormalities except in the case of complete rupture of the cuff when acromio-humeral articulation occurs.

5. The lesions are all explicable on a traumatic basis. There is no correlation with the presence or absence of osteoarthritic disease of the joint.

6. The biceps tendon may become damaged or even ruptured in this condition.

7. Villous synovial proliferation was found in fourteen cases, in five of which it was pigmented with histological appearances resembling pigmented villonodular synovitis. The significance of this finding is briefly discussed.