Myoma, of striped (rhabdomyoma) and smooth (leiomyoma) muscular tissue,
Neuroma, of nerve tissue,
Angioma, of blood-vessels,
Lymphangioma, of lymphatics,
Lymphoma (?), of lymph-gland tissue.
EPITHELIAL GROUP.
Epidermis:
Callus,
Corn,
Keratosis,
Horn,
Onychoma.
Epithelium of mucous membranes or glands:
Struma (?),
Adenoma,
Cystoma.
In the above varieties the growth of epithelium is more or less typical, a simple hyperplasia, either alone or combined with the new formation of fibrous tissue. Only the last three members of the series are tumors in the limited sense.
CANCER.
Cancer remains as an epithelial tumor, representing the atypical growth of cells resembling epidermis or the epithelium of glands and mucous membranes, extending into parts where epithelium is not found as a normal constituent. A new formation of connective tissue is usually associated with that of the epithelial cells.
Numerous varieties of cancer are described, according to the physical and structural peculiarities of the tumor. The scirrhus and encephaloid of the earlier writers are now transformed into fibrous and medullary cancer. This change in name is due to the stress laid upon the predominance of the fibrous stroma as the usual cause for the hard, dense, scirrhous cancer, while an abundance of epithelioid cells in relatively large alveoli is present in the encephaloid, marrow-like, medullary variety.