Squamous cell carcinoma (SCC) is a type of cancer that begins in the squamous cells, and is one of the most common types of skin tumors in chickens. Squamous cells are the thin, flat cells that make up the epidermis, or the outermost layer of the skin. SCC is caused by changes in the DNA of these cells, which cause them to multiply uncontrollably. Squamous cells make up the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the lining of the respiratory and digestive tracts. Lesions can develop throughout any of these areas.
Chickens develop skin lesions that look like crater-shaped ulcers with raised margins and found most frequently in the skin of the head, around the beak, eyelids, neck, chest or wings. Small nodular lesions are often found with the ulcers and appear grossly as enlarged feather follicles.
Previous reports of SCC lesions in chickens include the following cases:
- Inside the oropharynx and esophagus of an adult Japanese bantam rooster
- Inside the pharyngeal cavity of a 3-year-old Jersey black giant rooster.
- On the exterior of both legs of a 6-year old Aracauna chicken (sex is not known).
- Along the outside of the crop of a 4.5 year old rooster (breed is unknown).