Figure 1: Self resolving keratoacanthoma in 2-year-old male rat.
Case history and photos.

History

Male hairless rat 2 years old. History of skin problems including small abscesses and cysts.

Clinical Signs

Growth on the rat’s left cheek began as a red bump that quickly enlarged to a hard raised black mass.

Diagnosis

Initial diagnosis was a cornified cyst. Pathology revealed that the growth was actually a Keratoacanthoma.

Treatment

The vet prescribed an antibiotic ointment to prevent infection and help soften the tissue.

Outcome

The keratoacanthoma eventually fell off leaving a small hole in the cheek that healed well. To date there have been no more incidents of KA.

Photos

Male hairless rat with keratoacanthoma on left cheek