Immunotherapy of a squamous cell carcinoma in the perianal region using autologous dendritic cells in a horse

Abstract

Summary A 23‐year‐old Trakehner mare was referred to the Department of Large Animal Medicine with an ulcerative cleft tumour dorsal of the anus and in poor body condition. An infiltrative growing squamous cell carcinoma (SCC) was diagnosed. Surgical treatment was not an option because of the tumour localisation and topical chemotherapy caused severe side effects (coprostasis), therefore an immunological therapeutic approach involving autologous monocyte‐derived dendritic cells (DC) presenting tumour antigen on their surface was chosen. Dendritic cells were administered to the patient three times at intervals of four weeks to induce an immune response against the SCC. The tumour regressed in size, the ulcerated surface healed, body condition improved and coprostasis subsided. Six and a half months later small papillomatous neoplasms at the tumour scar led to a fourth treatment. During follow‐up, those recurrences remained indifferent; the mare showed physiological behaviour and returned to leisure riding. This case report describes the effectiveness of so far infrequently described immunotherapy with DC in horses.

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

“…The location of SCC in this case in the perianal region is extremely unusual with few previous reports (Wilson ; Arnold et al . ). The difficulty in treating squamous cell carcinomas of the perianal region has been reported, with proximity to the anus and difficulties in performing complete excision emphasised (Arnold et al .…”

“…Squamous cell carcinoma in the perianal region of horses has been rarely reported (Wilson ; Arnold et al . ). In humans, certain papillomaviruses have been identified as the causative agents of SCCs of genital and other mucosal and cutaneous regions (Sykora and Brandt ).…”

“…Treatment of squamous cell carcinoma in horses usually depends on the size and locality of the lesion (Arnold et al . ). At easily accessible locations, a sole surgical therapy may allow the entire tumour to be removed (Dietz ).…”

“…If the anatomical site is difficult to access, surgery infrequently provides satisfactory results (Hewes and Sullins ; Arnold et al . ).…”

“…Successful outcomes have been reported with small lesions or in addition to surgical reduction (Hewes and Sullins ; Arnold et al . ).…”