Nasal dermoid sinus cysts in the dog.

OBJECTIVE

To describe the clinical and morphologic characteristics of nasal dermoid sinus cysts in the dog.

STUDY DESIGN

Retrospective clinical study.

ANIMALS

Six client-owned dogs.

METHODS

Medical records (1995 to 1999) of 6 dogs that had a discharging sinus in the midline of the nose removed surgically were reviewed for signalment, physical examination, surgical and histopathologic findings, and outcome.

RESULTS

Three golden retrievers, 1 springer spaniel, 1 cocker spaniel, and 1 Brittany spaniel with a history of intermittent discharge from a small opening in the midline on the bridge of the nose at the junction between the nasal planum and the skin were identified. The condition was unresponsive to antibiotic therapy, and previous surgical excision had been unsuccessful in 3 dogs. None of the dogs had any other congenital defects, and all dogs responded to complete surgical excision of the tract and cyst. On histopathologic examination of excised tissue, there were adnexal structures along a tract lined with stratified squamous epithelium, consistent with a developmental abnormality of ectodermal tissue.

CONCLUSIONS

The lesions were diagnosed as nasal dermoid sinus cysts, similar to the congenital condition described in humans. Nasal dermoid sinus cysts are rare developmental defects related to abnormal development of the pre-nasal space and may extend into the cranial vault causing cerebral abscesses or recurrent meningitis. Complete surgical excision has a good prognosis.

CLINICAL RELEVANCE

This is a new condition that should be added to the surgical differential diagnosis for a discharging sinus over the external nares in dogs.