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Pigmented villonodular synovitis (PVNS) is a rare condition. Our purpose is to describe the largest series of patients with shoulder PVNS, massive irreparable rotator cuff tear, and glenohumeral osteoarthritis treated with arthroscopic debridement and synovectomy. We treated 9 patients with PVNS of the shoulder, irreparable rotator cuff tear, and slight glenohumeral arthropathy (group I). Patients underwent arthroscopic synovectomy and debridement. Results [constant score (CS) and subjective shoulder value (SSV)] were compared to those obtained from a control group (group II) of 20 consecutive patients undergoing arthroscopic debridement for irreparable cuff tear associated with hemorrhagic synovitis with no or slight glenohumeral arthropathy. Histologic examination was obtained in all cases to obtain the correct diagnosis. The preoperative shoulder function in group I was reduced with respect to group II. Upon follow-up, CS and SSV were lower in group I. Preoperatively, the differences relating to the CS value and to each item of the score were always statistically significant; instead, at follow-up, significant differences emerged in the CS, ADL, and ROM. At follow-up, significant differences emerged between CS of group I and of group II without glenohumeral arthropathy. Differences using the SSV were always statistically significant. The poor functional outcome of patients affected by PVNS can be attributed to the coexistence of the irreparable cuff tear and to the glenohumeral arthropathy. All patients with PVNS had shoulder osteoarthritis; it cannot be simply attributed to natural history of massive irreparable cuff tears, but to the pigmented villonodular synovitis.

Medullary thyroid carcinoma (MTC) is a rare human tumor affecting the calcitonin-secreting c-cells of the thyroid. Here we report that two independent strains of transgenic mice expressing a Polyomavirus (Py) truncated middle-T antigen (deltaMT), consisting of the amino-terminal 304 amino acids, and the full length Py small-T antigen, developed multifocal bilateral MTCs with 100\% penetrance. Occasionally one strain also developed mammary and bone tumors. Furthermore, offspring from both transgenic lines displayed pronounced waviness of the whiskers and fur, previously associated with defective epidermal growth factor receptor signaling. Transgene transcription, driven by the homologous early promoter/enhancer, and the corresponding translation products were detected in tumors and in many other organs which did not develop pathologies. The subcellular distribution of deltaMT and its interactions with the adapter proteins of the SHC family have also been analysed. Our study describes a novel murine model of MTC and provides evidence that the N-terminal 304 amino acid fragment of Py middle-T antigen, possibly in co-operation with small-T antigen, acts as a potent oncogene in c-cells of the thyroid.