Epithelioid sarcoma. A diagnostic problem.

Twelve cases of epithelioid sarcoma have been reviewed, illustrating the diagnostic problems for which this rare tumor has become notorious and demonstrating varied rates of tumor progression. The histological features most helpful to the distinction of epithelioid sarcoma from other nodular skin lesions, including benign conditions such as rheumatoid nodule and granuloma annulare, are discussed. The ultrastructural appearances of two cases were similar to immature mesenchymal tissue.