Several cauliflower-like alopecic masses arose on the head of an otherwise healthy, full-term newborn Jersey × Belgian blue heifer, which was humanely destroyed shortly after birth due to the severity of the skin lesions. Microscopically, the masses were composed of multiple papillary projections displaying well-differentiated sebaceous glands surrounded by a moderate number of well-developed sweat glands, as well as embryonic and fully developed, but dysplastic hair follicles. Thick branching connective tissue stalks supported these adnexal components. The papillated surface, the predominance of sebaceous glands, the presence of embryonic hair follicles and the well-differentiated sweat glands were compatible with nevus sebaceous, a rare form of cutaneous hamartoma described in man, dogs, cats and cattle. However, the cauliflower-like growth pattern, the presence of supportive thick branching connective tissue stalks and the relative abundance of dysplastic hair follicles in association with nevus sebaceous has not been described in the human or veterinary literature. A diagnosis of panadnexal papillomatous hamartoma was made in this case.