[Proliferating myositis]

A clinico-morphological analysis of 6 cases of proliferating myositis is presented. The patients varied in ages from 31 to 59 years. All the patients reported an extremely rapid growth of swellings: the period from the moment of the "tumour" detection to the operation was within 1 month, and in 4 cases 2 weeks. The main features of the microscopic structure of proliferating myositis included marked proliferation of fibroblasts and random arrangement of large cells with basophilic cytoplasm resembling rhabdomyoblasts and ganglionic cells. A detailed clinico-morphological analysis of the disease permits to differentiate proliferating myositis from similar soft tissue neoplasms (embryonal rhabdomyosarcoma, ganglioneuroblastoma, fibrosarcoma, extraabdominal desmoid, nodular fascitis).