Alexis Thomson,
Manual of Surgery, Sixth Edition…
(1921)
“ Malignant tumours may be primary in the muscle, or may result from extension from adjacent growths--for example, implication of the pectoral muscle in cancer of the breast--or they may be derived from tumours situated elsewhere. The diagnosis of an intra-muscular tumour is made by observing that the swelling is situated beneath the deep fascia, that it becomes firm and fixed when the muscle contracts, and that, when the muscle is relaxed, it becomes softer, and can be moved in the transverse axis of the muscle, but not in its long axis. ”
