Soft tissue tumours: The surgical pathologist's perspective

Abstract

The diagnosis of soft tissue tumours has always been difficult and controversial. This was mainly due to the rarity of these lesions, comprising ≤1% of all malignant tumours. Nevertheless, according to the Surveillance, Epidemiology, and End Results (SEER) database, about 15,000 cases of both bone and soft tissue tumours are diagnosed annually in the US. This puts soft tissue and bone tumours in the same order of magnitude as myeloma, gliomas and cervical carcinoma. Previously, the clinical importance of the exact histological typing of soft tissue tumours by the pathologist was limited, knowing that grade and stage, and not histological type determined treatment options. The pathologist merely served to grade the lesion and to exclude malignant non-sarcomatous, benign or pseudotumoral lesions. The small number of lesions in particular of single histological types and the poorly defined pathological criteria are the major sources of discordances in diagnostic soft tissue pathology. Even in specialist centres about 510% of soft tissue lesions remain unclassified. Recently, using transcriptional gene profiling complemented with, e.g. tissue microarrays, new potential therapeutic markers of histiotype-specific soft tissue tumours have emerged, e.g. CD117 (c-kit) and DOG1 for gastrointestinal stromal tumours,PDGFRβ in dermatofibrosarcoma protuberans and EGFR1 for synovial sarcomas, which in some cases might even be able to predict therapy response and prognosis [13]. These advances have led to an increased appreciation of the importance that histological typing might have in predicting natural history and treatment sensitivity of soft tissue tumours. Tumour tissue procurement and exact tissue handling are critical issues to provide the pathologist with adequate and well preserved tissue, in order to perform the necessary ancillary studies for making an exact diagnosis. Cross-talk between pathologists, radiologists and clinicians is crucial in obtaining this goal.