Clinical Rounds: Battling a Labrador's oral malignant melanoma - Veterinary Medicine
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Clinical Rounds: Battling a Labrador's oral malignant melanoma
After a referring veterinarian diagnosed this deadly neoplasm in a senior Labrador retriever, this team of experts stepped in to help extend the dog's life with targeted treatment. What can you learn from their approach to help your patients?



Laura Hammond, DVM

Laura Hammond, DVM
As with most oncology patients, the goals of diagnostic imaging in patients with oral malignant melanoma are to identify the extent of local disease, guide tissue sampling, and screen for metastases and concurrent diseases. Evaluation of the primary oral mass may be performed with either skull radiographs or cross-sectional imaging (CT or magnetic resonance imaging). While radiographs may identify some osseous lesions of the skull, CT is a more sensitive modality for detecting both osseous and soft tissue abnormalities of the head and neck.

CT features of malignant melanoma include variable lysis of adjacent bone, soft tissue swelling, and variable contrast enhancement.7 Contrast-enhanced CT can be used to guide tissue sampling and plan surgical margins of the primary mass since it allows differentiation of typically strongly enhancing tumor tissue from non-enhancing areas (e.g. central necrosis or hemorrhage) or less enhancing adjacent normal tissue.

CT features of lymph node metastasis include heterogeneous contrast enhancement and variable lymphadenomegaly. Mild lymphadenomegaly can be difficult to detect on physical examination but may be readily apparent on CT.

Screening for pulmonary metastases may be accomplished by using either three-view thoracic radiographs or thoracic CT, although CT is much more sensitive than thoracic radiographs for detecting pulmonary metastases and is highly recommended for accurate staging,8 especially in patients requiring costly treatments or extensive surgical therapy.


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