June 2015
Peer Reviewed

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Ceruminous cystomatosis (ie, ceruminous adenoma, apocrine cystadenomatosis) is an uncommon, nonneoplastic disorder of cats. Lesions most commonly affect the concave pinna, external auditory canal opening, and occasionally the auditory canal. To date, it is thought to represent a congenital or degenerative and senile change. The condition affects cats of all ages, but cysts are more commonly encountered with middle-aged to older cats. A breed predisposition for Abyssinian and Persian cats has been reported, along with a slight predominance in males.1

Related Article: Common Masses in Dogs & Cats

Clinically, lesions are striking and consist of multiple discrete to coalescing blue-gray or purple papules, vesicles and/or nodules (Figures 1 & 2). On rupture of cysts, a yellow-brown to black viscous fluid is easily expressed (Figure 3). Because of the unique presentation, diagnosis is typically straightforward if the clinician is aware of the disease; however, early or small lesions may be mistaken for melanocytic or vascular tumors. Diagnosis is confirmed via histopathology, which reveals clusters of cystic glands.

Lesions tend to be cosmetically disturbing for owners, but signs are not usually present if lesions remain small. Ceruminous cystomatosis becomes a problem when lesions enlarge and occlude the canal, which disrupts normal self-cleaning. Disruption of normal otic physiology creates a favorable microenvironment for microbial proliferation which results in secondary otitis externa.

Related Article: Skin Clues to Canine Endocrine Disease

Treatment of ceruminous cystomatosis is typically not warranted unless cysts are enlarging and likely to occlude the ear canal or their presence is resulting in recurrent otitis externa. Ablation of cysts via a carbon dioxide laser is the preferred treatment method; however, surgical excision, cryotherapy, and chemical cautery have been proposed as alternate treatments.

In the experienced practitioner’s hand, laser ablation affords fine control of the treated area, minimizing collateral tissue damage and scar formation, which results in minimal deformation of the pinna.

With appropriate therapy, long-term resolution is quite good, but more than one procedure may be required, depending on the extent and severity of cysts at presentation.

References and author information Show


  1. Gross TL, Ihrke PJ, Walder EJ, Affolter VK, eds. Feline ceruminous cystomatosis. Ames, IA: Wiley-Blackwell; 2006:667-668.

Suggested Readings

  • Duclos D. Lasers in Veterinary Dermatology. Vet Clin North Am Small Anim Pract. 2006;36(1):15-37.
  • Miller WH, Griffin CE, Campbell KL, eds. Muller and Kirk’s Small Animal Dermatology, 7th ed. St. Louis, MO: Elsevier Saunders; 2013:741-767.
  • Sula MJ. Tumors and tumorlike lesions of dog and cat ears. Vet Clin North Am Small Anim Pract. 2012;42(6):1161-1178.

Darren Berger

DVM, DACVD Iowa State University

Darren Berger, DVM, DACVD, is assistant professor of dermatology at Iowa State University. Dr. Berger’s research interests include clinical pharmacology, dermatomycoses, and clinical management of canine atopic dermatitis and equine hypersensitivity disorders. After earning his DVM from Iowa State University, he completed a dermatology residency with Dermatology for Animals in Gilbert, Arizona.

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