MALIGNANT SOFT-TISSUE TUMORS IN A LARGE REFERRAL POPULATION - DISTRIBUTION OF DIAGNOSES BY AGE, SEX, AND LOCATION

OBJECTIVE. The purpose of this study was to determine the relative pre valence, age at presentation, sex distribution, and skeletal distribut ion of malignant soft-tissue tumors and to ascertain the relative freq uency of these tumors in specific anatomic locations and age groups am ong a population of patients in a large pathologic consultation servic e. MATERIALS AND METHODS. The computer diagnoses of 39,179 lesions occ urring in 38,484 patients seen by soft-tissue pathologists at the Arme d Forces Institute of Pathology during the 10-year period from January 1, 1980, to December 31, 1989, were retrospectively reviewed. All les ions were placed in one of 121 major categories in accordance with the classification system used by the World Health Organization and coded to one of 32 anatomic locations, such as hand, wrist, forearm, and so forth. Age and sex also were recorded. For purposes of analysis, all lesions were placed in one of 10 categories: hand and wrist, upper ext remity, proximal limb girdle (axilla and shoulder), foot and ankle, lo wer extremity, hip and buttocks region, head and neck, trunk, retroper itoneum, and other lesions. The study group included 31,047 mesenchyma l lesions, of which 12,370 were malignant. RESULTS. More than 80% of m alignant tumors were classified into eight diagnostic categories: mali gnant fibrous histiocytoma (24%), liposarcoma (14%), leiomyosarcoma (8 %), malignant schwannoma (6%), dermatofibrosarcoma protuberans (6%), s ynovial sarcoma (5%), fibrosarcoma (5%), and sarcoma, not classified f urther (12%). Approximately 79% of all malignant tumors were classifie d into five diagnoses for each age and location. With the distal upper extremity (hand and wrist) as an example, 50% of malignant lesions in the 16-25-year-old group were classified as epithelioid sarcoma (29%) , malignant fibrous histiocytoma (13%), and synovial sarcoma (8%). For the same location but for children 5 years old or younger, almost 50% of malignant tumors were classified as infantile fibrosarcoma. CONCLU SION. Despite the multitude of pathologic possibilities, most malignan t soft-tissue tumors are classified into a small number of diagnoses. These may be further defined when the location of the lesion and the a ge of the patient are considered. Knowledge of tumor prevalence will a ssist radiologists in establishing a suitably ordered differential dia gnosis when a soft-tissue tumor has a nonspecific radiologic appearanc e.