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

OBJECTIVE. The purpose of this study was to determine the specific dia gnoses, relative prevalence, and the age, sex, and skeletal distributi on of benign soft-tissue tumors and to ascertain the relative frequenc y of these tumors in specific anatomic locations and age groups among a population of patients in a large pathologic consultation service. M ATERIALS AND METHODS. The computer diagnoses of 39,179 lesions occurri ng in 38,484 patients seen by the Armed Forces Institute of Pathology soft-tissue pathologists during the 10-year period starting January 1, 1980, and ending December 31, 1989, were retrospectively reviewed. Al l lesions were placed in one of 121 major categories in accordance wit h the classification system used by the World Health Organization and coded to one of 32 anatomic locations such as hand, wrist, and forearm . Age and sex of the patients were also recorded. For purposes of anal ysis, all lesions were placed in one of 10 categories: hand and wrist, upper extremity, proximal limb girdle (axilla and shoulder), foot and ankle, lower extremity, hip and buttocks region, head and neck, trunk , retroperitoneum, and other lesions, The study group included 31,047 mesenchymal lesions, of which 18,677 were benign. RESULTS. Approximate ly two thirds of soft-tissue tumors were classified into seven diagnos tic categories: lipoma and lipoma variants (16%), fibrous histiocytoma (13%), nodular fasciitis (11%), hemangioma (8%), fibromatosis (7%), n eurofibroma (5%), and schwannoma (5%). Approximately 80% of all benign tumors were placed in seven diagnostic categories for each age and lo cation. In the retroperitoneum, for example, approximately half the be nign lesions in the 16- to 25-year old group were fibromatosis (20%), schwannoma (14%), and neurofibroma (13%). For the same location in chi ldren 5 years old or younger, almost two thirds of the benign tumors w ere lipoblastoma (37%) or lymphangioma (26%). CONCLUSION. Despite the large number of pathologic possibilities, most benign soft-tissue tumo rs are classified into a small number of specific diagnostic categorie s. These may be further defined when the location of the lesion and th e age of the patient are considered, Knowledge of tumor prevalence wil l assist the radiologist in establishing a suitably ordered differenti al diagnosis when a soft-tissue tumor has a nonspecific radiologic app earance.