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Title: Metastatic Malignant Melanoma in an alpaca (Vicugna pacos)

Author
item MOLLAT, WENDY - PILCHUCK VET HOSPITAL
item Gailbreath, Katherine
item ORBELL, GEOFFREY - Washington State University

Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2008
Publication Date: 1/6/2009
Citation: Mollat, W.H., Gailbreath, K.L., Orbell, G.M. 2009. Metastatic Malignant Melanoma in an alpaca (Vicugna pacos). Journal of Veterinary Diagnostic Investigation. 21(1):141-144.

Interpretive Summary: Malignant melanoma in a 7-year old, intact male alpaca with a chronic, non-healing wound on the left nares, weight loss and inappetance is described. Malignant melanoma was diagnosed in small biopsy specimens from a mass on the maxilla associated with the non-healing wound and from a mass in the submandibular region. The alpaca was humanely euthanized 10 days after the diagnosis based upon the poor prognosis and rapid clinical deterioration. At postmortem examination the alpaca had an ulcerated, 8.0 x 6.0 x 4.0 cm, multilobulated, black pigmented mass that infiltrated the bone and bone marrow of the upper jaw and protruded into the left nasal cavity. Numerous additional discrete to coalescing masses were present in the subcutaneous tissue of along the neck, scattered over the surfaces of the thoracic cavity and throughout the lung. All masses were black on cut surface and exuded black pigment. Histologically the masses were composed of spindloid to polygonal cells with indistinct cell borders and moderate amounts of cytoplasm that contained fine black melanin granules which confirmed the diagnosis of metastatic malignant melanoma. Melanoma in domestic animals which special reference to camelids is discussed.

Technical Abstract: Malignant melanoma in a 7-year old, intact male alpaca with a chronic, non-healing wound on the left nares, weight loss and inappetance is described. Malignant melanoma was diagnosed in punch biopsy specimens from a mass on the maxilla associated with the non-healing wound and from a mass in the submandibular region. The alpaca was humanely euthanized 10 days after the diagnosis based upon the poor prognosis and rapid clinical deterioration. At postmortem examination the alpaca had an ulcerated, 8.0 x 6.0 x 4.0 cm, multilobulated, black pigmented mass that infiltrated the left ventral maxillary bone into the marrow space and protruded into the left nasal cavity. Numerous additional discrete to coalescing masses were present in the subcutaneous tissue of the submandibular area along the trachea,scattered over the pericardium and the parietal surface of the diaphragm and pleura and throughout the pulmonary parenchyma. All masses were black on cut surface and exuded black pigment. Histologically the masses were composed of spindloid to polygonal cells with indistinct cell borders and moderate amounts of cytoplasm that contained fine black melanin granules .