Malignant Lymphoma in the Dog and Cat

DIAGNOSIS AND STAGING – DOGS The typical dog with LSA will present with generalized (or less commonly regional) lymphadenopathy. Differential diagnoses for generalized adenopathy can include Ehrlichiosis or other immune-mediated diseases, systemic mycosis, severe pyoderma or other skin disease, and reactive hyperplasia. The most simple way do discern the cause for lymphadenopathy is via needle aspiration cytology of an affected lymph node. If possible, the submandibular lymph nodes should be avoided due to the likelihood of some component of reactive hyperplasia being present due to drainage from the mouth and ears. Although many clinical pathologists are able to confirm a diagnosis of canine LSA cytologically, excisional biopsy of an affected lymph node provides the most information. It is critical that empiric prednisone therapy not be employed prior to diagnosis if lymphoma is a differential, as this may mask the signs of illness and has the potential to induce resistance to other forms of chemotherapy (See below).