ИСТИНА

Hypertrophic osteopathy (HO) is a syndrome characterized by progressive periosteal proliferation that mainly affects long bones of thoracic and pelvic limbs. In most cases, HO is secondary to intrathoracic lesions of neoplastic, inflammatory or degenerative origin. Paraneoplastic HO is commonly associated with pulmonary tumours and rarely diagnosed in companion animals with abdominal malignancies. The pathoetiology of HO remains elusive with proposed mechanisms of vascular factors release, neurohumoral influence, increased peripheral blood flow and proliferation of connective tissue. Materials and methods: A 14-year-old neutered male cat was admitted to the clinic with bilateral lameness and soft tissue swelling on the distal parts of all extremities. Clinical examination and abdominal ultrasonography detected a tumour of left kidney (3 × 4 cm) while computer tomography confirmed diagnosis of the malignant growth with no presence of metastasis. Radiographs revealed periosteal bone formation on the long bones of all four limbs. The cat underwent radical left nephroureterectomy. At histopathological examination of the affected kidney papillary renal cell carcinoma was observed. Results: During two-month period after the surgery clinical improvement in mobility, pain relief were noted in the patient. At a follow-up of 8 months neither metastatic dissemination nor local recurrence was detected. Conclusions: The present clinical case shows beneficial effect of surgical excision of primary tumour in alleviating clinical signs of paraneoplasic HO. Papillary renal cell carcinoma should be included in the list of underlying oncological diseases associated with HO in cats.