Surgical resection of a squamous cell carcinoma in the perianal region of a 25‐year‐old crossbred American Paint gelding using sharp surgical excision, laser excision and chemotherapy

Abstract

Summary A 25 year‐old American Paint gelding was referred to the Onderstepoort Academic Veterinary Hospital with an ulcerated lesion of nonpigmented skin at the right lateral aspect of the perianal region. An infiltrating squamous cell carcinoma was suspected. Surgical excision and ablation with sharp surgical excision and a diode laser was performed although complete excision was not possible due to the tumour location. Intralesional chemotherapy was performed at the completion of the surgical excision and continued in the post‐operative period. Histological examination of the excised lesion confirmed a diagnosis of squamous cell carcinoma and revealed incomplete resection margins at the medial, dorsal and ventral aspects of the surgical site. The surgical site healed uneventfully and a re‐examination at 6 months post‐surgery revealed the gelding to have normal clinical parameters with no perianal lesions.

Cutaneous squamous cell carcinoma (SCC): “What's the problem?”

“…In the case described by Poore et al . in this edition (), a carcinoma developed in nonpigmented skin around the anus – it is impossible again to believe that sunshine played a part in its development. Other potential factors suggested to be involved include chronic irritation or infection, cutaneous burns, poor wound healing and parasitic diseases (e.g.…”

“…() and could probably have been useful in the case described by Poore et al . (). Reported case series using intra‐ or peri‐lesional chemotherapy in slow release emulsions have been uniformly impressive.…”

“…The case described in this edition by Poore et al . () was treated with a combination of surgical tumour reduction and chemotherapy. In the case described by Poore et al .…”

“…Poore et al . () instigated the chemotherapy with repeated aqueous 5‐fluorouracil immediately after the surgery; this is always the pragmatic option to maximise the prognosis. A slow release method based on an emulsion of cisplatin, carboplatin or 5‐fluorouracil with sesame oil has been used successfully by several previous authors including Théon et al .…”

“…Since SCC is commoner in older horse (Valentine ), the advanced age of the horse in the case described by Poore et al . () may have played some part in its aetiopathogenesis. The correct choice of treatment is imperative and the best available combination method should always be employed.…”