Abstract:
Cutaneous squamous cell carcinoma (SCC) is a slow growing but locally invasive neoplasm,
most commonly caused by prolonged exposure to ultraviolet (UV) radiation. Whilst SCC
accounts for 15% of skin tumours in domesticated cats, cutaneous SCC in non-domesticated
felids (apart from captive snow leopards) appears to be uncommon, with only three reports
in the literature to date. In this report, a captive African lion (Panthera leo) presented with
two ulcerative lesions on the nasal planum. Histopathology of the lesions revealed epidermal
keratinocyte dysplasia and neoplastic basal- and supra-basal epithelial cells with dyskeratosis
and evidence of basement membrane breaching and dermal invasion, consistent with a
diagnosis of SCC. There was also evidence of laminar fibrosis and inflammation of the
subjacent dermis suggesting that the SCC most likely resulted from UV-induced neoplastic
transformation of the epidermal squamous epithelium following actinic keratosis. The lion
was treated with hypofractionated radiation therapy and remained in remission until his
death (euthanised 17 months later because of age-related chronic renal failure). This is the
first report of cutaneous SCC in a lion with evidence of actinic damage and resolution after
radiation therapy.
