Champion et al (2023) reported on a case. The cyst had a pore to the surface and was lined by infundibular epithelium.
Champion CP, Edginton HD, Peters-Kennedy J. Dilated pore of Winer in a dog. J Comp Pathol. 2023; 208: 22-23
A hamartoma is a proliferation of mature tissue in a location where it is normally found. Hamartomas are found in the very young and in older animals. In humans, some hamartomas are known to arise because of loss of function of genes that limit the mTOR (mechanistic target of rapomycin) pathway and activity particulary in Tuberus Sclerosis Complex.
Cutaneous horn
Linear organoid nevus
There is a case report about a dog with a linear mass composed of sebaceous glands.
Warty dyskeratoma
Seborrhiec keratoma
Sebaceous nodular hyperplasia
Pilar neurocristic hamartoma
This hamartoma derives its name from a hair follicle (pilar) and mesenchymal cells of the neural crest, usually with spindle cells, Schwann cells, pigmented dendritic cells and or melanocytes.They are often pigmented in appearance. They are multifocal/multinodular.
Anderson WI, Luther PB, Scott DW. Pilar neurocristic melanoma in four dogs. Vet Rec. 1988; 123: 517-518.
Smooth Muscle Hamartoma
Well demarcated and expansile nodules of smooth muscle that form a mass in the dermis is a smooth muscle hamartoma. These are derived from the arrector (erector) pili muscle.
Liu SM, Mikaelian I. Cutaneous Smooth Muscle Tumors in the Dog and Cat. Vet Pathol 2003; 40: 685–692