Mucosal cancer (C. mucosum) is a relatively rare, little-studied malignant tumor of the mucous membrane of the respiratory tract in humans and animals, caused by a fungus of the genus Aspergillus. The first information about mucosal cancer indicates that this tumor is a product of spontaneous reproduction of Aspergillus mucosus blastospores. Its elements are characterized predominantly by monomorphism in anamospores measuring 30-65 x 5-15 µm, usually bearing only one amoeboid daughter cell.