ABSTRACT
Some nodular dermatoses may be diagnosed with a fine-needle aspirate or physical exam alone and other nodular dermatoses represent more serious disease and require a biopsy for diagnosis. A dermatophyte kerion is caused by a granulomatous immune response to dermatophytic fungal infection in dogs. Cutaneous histiocytoma is a benign nodular proliferation of Langerhans' cells. Cutaneous histiocytosis and systemic histiocytosis are non-cancerous proliferations of perivascular dermal dendritic cells. Canine eosinophilic granuloma appears to be a hypersensitivity reaction. The precipitating cause is unknown in many instances, but some cases may be hypersensitivity reactions to arthropod bites or insect stings. Infundibular keratinising acanthomas are follicular cysts that may be multiple and problematic in dogs. In dogs, typically there is a rapid appearance of papular, nodular, verrucous, fimbriated, donut-like or plaque-like lesions on the skin or mucous membranes.
