Cutaneous horn are a relatively common and innocuous skin disease in cats, and relatively simple to treat via surgical excision. Cutaneous horn are a circumscribed exophytic lesion composed of dense compact keratin. They are often associated with the footpads, but may be seen anywhere on the skin surface, in single growths or as multiple growths. An association with FeLV infection has been reported.
These horns, single or multicentric, are found mainly on the footpads and sometimes on the face.
Histopathology reveals severe, compact orthokeratotic keratosis and in some cases, dyskeratosis and epidermal multinucleate giant cells. These horns resemble other keratinisation disorders such as acquired ichthyosis or Reiter's syndrome seen in human AIDS patients. These hyperproliferative dermatoses might be the consequence of the same pathophysiological mechanism. It is unknown whether stimulation of keratinocytes is caused directly by the virus or by cytokines released by monocytes or T lymphocytes infected by teh HIV virus.
Differential diagnosis would include giant cell dermatosis.
Most cases require surgical removal of cutaneous horn due to mechanical irritation.
Surgical recurrence is common unless wide tissue margins are taken.