Dermoid Cysts (Lump Under Skin) in Dogs
Definition of Dermoid Cysts
Dermoid cysts are a type of non-cancerous tumor that forms in the middle layer of the skin during fetal development. They are fairly common in dogs, present at birth and probably hereditary. In their walled-off centers, these cysts contain skin flakes, hair, hair follicles, sweat and sebaceous gland secretions, nerve remnants and glandular debris. Dermoid cysts develop up singly or in clusters mostly along the top of the neck and back, which in medical lingo is called the dorsal midline. They also can occur on or around the eyes and ovaries. Dermoid cysts usually are harmless. Most dogs show no severe signs of discomfort or distress from these skin masses, other than itchiness. Occasionally, the cysts rupture and drain a thick, yellowish-brown fluid, although they usually refill over time. When a dermoid cyst ruptures for any reason, it can become inflamed, infected and quite painful.
Dermoid cysts are typically congenital (present at birth) and have a strong suspected hereditary component. They are fairly common in domestic dogs and rare in domestic cats. Dermoid cysts are considered to be developmental in origin, meaning that they develop in utero while the puppy’s cells, tissues and organs are being formed. The underlying cause is thought to be the failure of complete separation of the neural tube from the epidermis during embryogenesis. The neural
Most dogs with dermoid cysts or other forms of cutaneous (skin) or subcutaneous (beneath the skin) cysts are asymptomatic, meaning that they show no outward signs of discomfort, distress, unusual behavior or pain. If a cyst ruptures, it can become quite painful for the animal. They frequently are extremely itchy (pruritic), as well.Owners of a dog with dermoid cysts often bring their dog to the veterinarian for evaluation of soft, fluctuant to semi-solid, non-painful
There are several distinct types of cutaneous (skin) and subcutaneous (beneath the skin) cysts that can be seen in domestic dogs. Typically, cysts are identifiable visually and by physically feeling them on palpation. Dermoid cysts can be distinguished from follicular and infundibular cysts in several ways. A procedure called a fine-needle aspirate can be performed to obtain a tiny sample of the internal cyst material. This involves inserting a sterile needle into the center of
The goals of treating dermoid cysts are to remove them and, hopefully, to prevent their recurrence. Surgical excision is the treatment of choice.
Depending upon the size and location of the cysts, removal may be done under sedation and local anesthesia, or it may require general anesthesia. Usually, the surgical procedure is quite simple. Occasionally, however, the site of the cysts may become inflamed and infected postoperatively. If that happens, oral antibiotics and topical