ARS | Publication request: What is your diagnosis? Incidental melanosis of a salivary gland lesion

Submitted to: Journal of the American Veterinary Medical Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 2006
Publication Date: July 15, 2006
Citation: Pownder, S., Fidel, J.L., Saveraid, T.C., Gailbreath, K.L., Gavin, P.R. 2006. What is your diagnosis? Incidental melanosis of a salivary gland lesion. Journal of the American Veterinary Medical Association. 229(2):209-210.

Interpretive Summary: A dog presented to the Washington State University Veterinary Teaching Hospital for swelling at the base of the lower jaw. A fine needle aspirate revealed abundant melanin granules. Because malignant melanoma of the oral cavity was a possible diagnosis with a poor prognosis, magnetic resonance imaging (MRI) was performed to try and further characterize the mass. The MRI findings were also suggestive of the presence of large amounts of melanin. The mass was excised and diagnosed as non-neoplastic salivary gland inflammation and necrosis with melanin deposition.

Technical Abstract: An 8-year-old castrated male Bouvier des Flandres presented to the Washington State University Veterinary Teaching Hospital for evaluation of unilateral mandibular swelling. A fine needle aspirate revealed large amounts of melanin. Because of the proximity to the oral cavity and the poor prognosis associated with oral malignant melanoma, magnetic resonance imaging (MRI) was performed to further characterize the mass. A central hyperintense region on T1 weighted images which was hypointense on the T2-weighted images was consistent with large deposits of melanin. The mass was excised and no evidence of malignant melanoma was detected in the gland or local lymph nodes. Although squamous metaplasia was detected, the dog was healthy at 9 months post-surgery consistent with a benign etiology.