Definition of Skin Tumors
Tumors, commonly called masses, cancers or neoplasms, are composed of new, abnormally fast-growing tissue that serves no useful purpose for the affected animal. Tumors of the skin (cutaneous) and subcutaneous soft tissue (between the outer layers of skin and the inner layers of muscle or bone) are visible lumps or bumps often seen or felt by owners. Skin tumors are the most frequently diagnosed form of cancer in companion cats.
How Skin Tumors Affect Cats
The effect of skin tumors on cats depends on the type of tumor, its size and location and its degree of aggressiveness. Normally, either the owner notices the tumor or it is discovered incidentally during a routine veterinary examination. Sometimes, skin tumors cause pruritis (itchiness), pain and/or self-trauma from scratching. Depending on their location, skin tumors can interfere with vision, smell or eating. They also can affect ambulation when located on the toes, paws or pads.
Causes of Feline Skin Tumors
The skin and underlying subcutaneous tissues are structurally complex and involve various layers and networks of skin, fibrous connective tissue, blood vessels, fat and nerves. Tumors of these areas are diverse and difficult to classify.
Neoplasms are caused by the progressive and uncontrolled growth of cells and tissue. In most cases, the precise cause of skin tumors is not known. Sometimes, they may be induced by trauma, viral infection, irritation, vaccinations and/or exposure to ultraviolet radiation. Certainly, hormones and genetics may also contribute to the development of skin masses.
Preventing Skin Tumors
Cats at risk for and previously affected by squamous cell carcinoma should be kept out of direct sunlight as much as possible. Discuss the possibility of vaccine-induced fibrosarcomas with your veterinarian. Most types of tumors cannot really be “prevented,” since their cause is unknown.
The prognosis for cats with skin tumors depends entirely upon the tumor type, size, location, aggressiveness and degree of differentiation. Cats with basal cell tumors have a good prognosis, as the tumors are usually solitary and benign, and when malignant are of low-grade and rarely metastasize. Cats with multicentric fibrosarcoma caused by the feline sarcoma virus have a poor prognosis, because surgical removal typically is not possible.