Case Report: Topical imiquimod (Aldara®) as a palliative option for extensive canine facial cutaneous melanocytoma.

Cutaneous melanocytic neoplasms in dogs generally present as benign lesions, unlike their oral or digital counterparts, but treatment can be challenging when complete surgical excision is restricted by anatomical location. A 5-year-old neutered male Shiba Inu was evaluated for a firm, well-circumscribed, black-pigmented nodule measuring 4 × 3.8 cm on the left facial region, with surrounding pigmented papules. Histopathological examination of punch biopsy specimens confirmed cutaneous melanocytoma with superficial subcutaneous involvement observed in two samples. Complete surgical excision was not feasible due to the broad facial distribution of the nodule and surrounding papules. Consequently, topical immunotherapy with 5% imiquimod cream (Aldara®; 3 M Pharmaceuticals, St Paul, MN, USA) was initiated as a palliative treatment. After 5 months of treatment, the nodule decreased in size to 3.3 × 3.0 cm, became subjectively softer on palpation, and the number of surrounding papules decreased, with no observed adverse effects. Following discontinuation of treatment during a planned washout period before follow-up biopsy, the nodule increased in size, and histopathological findings remained consistent with the initial diagnosis. This case suggests that topical imiquimod may provide temporary clinical improvement and may be considered as a palliative or maintenance option for canine cutaneous melanocytoma when complete surgical excision is challenging.