Introduction

Tumors of soft tissues (STS) represent sarcomas covering a range of histological types which are classified according to tissue of origin. They occur relatively rarely, and incidence rates between countries do not differ significantly.

Histology, classification and diagnosis

Soft tissue sarcomas are derived from mesenchymal tissues such as muscle, fat, blood vessels and other connective tissues, a heterogeneity of cell type concealed by site-oriented classifications such as the ICD. There is no evidence that these diverse neoplasms have a common etiology.

The Third National Cancer Survey and the SEER Programme (Surveillance, Epidemiology and End Results) in the USA have provided tabulations for these cancers both by site and cell type for 1969-1971 and 1972–77 (Young et al., 1981). Leiomyosarcoma (30%) appears to be the most common form affecting mainly the uterus in females and the gastrointestinal tract in males. Liposarcomas (17%), fibrosarcomas (14%) and rhabdomyosarcomas (11%) are predominant in males. An increasing number of cancer registries are providing this type of information, although numbers are much smaller. However, the indexing of these cancers is such that some connective tissue malignancies are currently coded to specified organs such as uterus, stomach, rather than ICD-9 171. Kaposi's sarcoma (see below) is coded to malignant neoplasm of skin ICD-9 173. Unless diagnoses are coded by ICD-O (WHO, 1976, 1990), such neoplasms can be ‘lost’.