No abstract

The light microscopic appearances of Tru-cut needle biopsies from 50 consecutive soft tissue tumours were assessed by three pathologists and compared with the definitive histological diagnosis. Forty-four patients had soft tissue sarcomas and six had benign soft tissue lesions. A correct predictive diagnosis of sarcoma was made on 87-98 per cent of adequate Tru-cut specimens, the accuracy varying between pathologists. Three sources of diagnostic error were recognized: false positive cores (8 per cent), false negative cores (8 per cent), and cores inadequate for diagnosis (16 per cent). The major source of confusion related to difficulties in differentiating infiltrating fibromatosis from malignant fibrous histiocytoma. The high sensitivity of Tru-cut needle biopsy suggests that it could be a valuable aid in the diagnosis of clinically suspected soft tissue sarcomas.

Summary.-An in vitro osteolysis assay with 45Ca-labelled mouse calvaria has been used to investigate mechanisms of direct bone invasion by squamous carcinomas of the head and neck. Short-term (3-day) organ cultures of 8 fresh squamous carcinomas showed varying degrees of in vitro bone-resorbing activity which was blocked by indomethacin, an inhibitor of prostaglandin synthesis. Supernatant media from 6 established cell lines also induced bone resorption in vitro and evoked an osteoclastic response in the cultured calvaria. Osteolysis by supernatant media was not blocked by indomethacin in all the tumour-cell lines, and the production of nonprostaglandin osteolysins by the indomethacin-resistant lines is postulated. The two principal findings that emerge are: (1) Stimulants for osteoclastic activity are derived from both squamous-carcinoma cells and from host cells in the tumour stroma.(2) These stimulants are diverse. Indomethacin-sensitive agents, presumed to be prostaglandins, are most convincingly demonstrated in the fresh tumours. Indomethacin-resistant agents, presumably not prostaglandins, are more characteristic of the carcinoma cell lines.

Summary Northern analysis of tumour RNA has been used to examine the expression of members of the myf family of muscle determining genes (myf3, myf4, myf5 and (Davies et al., 1987) and the rat myogenin gene (Wright et al., 1989) which were both isolated by procedures involving subtractive cDNA hybridisation. Subsequently Braun et al. (1989b, 1990) isolated two related genes designated myf5 and myf6 from a human foetal muscle cDNA library and an additional two genes called myf3 and myf4 (Braun et al., 1989a) that are the human homologues of, respectively, MyoDI and myogenin.

Patterns of cartilage invasion by squamous carcinoma were examined in 34 consecutive laryngectomy specimens with particular reference to selective involvement of ossified cartilage. Direct infiltration of the laryngeal framework was demonstrated in 17 cases--16 (out of 17) transglottic carcinomas and in a simgle example of a combined glottic and infraglottic tumour. The susceptibility of ossified laryngeal cartilage to tumour invasion was confirmed, and morphological studies ahve clarified the underlying mechanisms. Invasion is a largely indirect process dominated by local bone destruction by osteoclasts, operating in front of the advancing tumour. One established, carcinoma cells infiltrate and erode bone alone, and the osteoclasts disappear. Reasons for the particular susceptibility of ossified laryngeal cartilage to tumour invasion are discussed and attention is drawn to the role of the tumour-associated osteoclast activating factors such as postaglandins. Therapeutic implications of cartilage invasion are noted.