Chapter 20 Lymphoma Flashcards
What is lymphoma in horses?
Lymphoma, also known as lymphosarcoma and malignant lymphoma, is the most common hematopoietic neoplasm in horses, affecting nearly every organ system.
What percentage of equine neoplasias does lymphoma account for?
Up to 3% of all equine neoplasias.
What are the four main categories of equine lymphomas?
Multicentric, alimentary, mediastinal, and cutaneous.
What are common clinical signs of lymphoma in horses?
Weight loss, lethargy, lymphadenopathy, edema, anemia, hyperfibrinogenemia, hyperproteinemia, hyperglobulinemia, and hypoalbuminemia.
What is the prognosis for equine lymphoma?
The prognosis is generally grave, but palliative therapies such as surgical excision, radiation therapy, and chemotherapy can improve quality of life and prolong survival time.
What age group is most commonly affected by lymphoma in horses?
Mean ages range from 5-10 years, though cases have been reported in aborted fetuses, foals, and horses of advanced age.
What is multicentric lymphoma?
A form of lymphoma characterized by variable involvement of nearly any organ system through metastasis of neoplastic lymphocytes.
What organs are commonly affected by multicentric lymphoma?
Spleen, liver, kidneys, heart, reproductive and urogenital tracts, central nervous system, eye, and upper airway.
What clinical signs are associated with lymphoma involving the central nervous system?
Neurologic deficits such as ataxia, blindness, lameness, seizures, paresis, cranial nerve deficits, and Horner’s Syndrome.
What is alimentary lymphoma?
A form of lymphoma characterized by diffuse or segmental infiltration of the gastrointestinal tract with neoplastic lymphocytes.
What age group is often affected by alimentary lymphoma?
Young horses less than five years old.
What are common clinical signs of alimentary lymphoma?
Weight loss, hypoalbuminemia, reduced oral glucose absorption efficiency, ventral edema, and peritoneal effusion.
What is mediastinal lymphoma?
The most common thoracic neoplasm in horses, originating from lymphoid tissues in the thymus or mediastinal lymph nodes.
What clinical signs are associated with mediastinal lymphoma?
Tachycardia, dyspnea, distended jugular pulses, ventral edema, pleural effusion, muffled heart sounds, coughing, and respiratory distress.
What is cutaneous lymphoma?
A form of lymphoma characterized by dermal or subdermal nodules, which can be found in nearly any location on the integument.
What are common clinical signs of cutaneous lymphoma?
Well-circumscribed, firm, non-painful nodules, often covered by normal skin and hair, though alopecia and ulceration may occur.
What is epitheliotropic lymphoma?
A rare form of cutaneous lymphoma characterized by severe, generalized or multifocal exfoliative dermatitis with alopecia, scaling, and crusting.
What are common paraneoplastic syndromes associated with equine lymphoma?
Hypercalcemia, pseudohyperparathyroidism, immune-mediated anemia, immune-mediated thrombocytopenia, erythrocytosis, eosinophilia, hypoglycemia, hypertriglyceridemia, hypertrophic osteopathy, hypertrichosis, and polyuria/polydipsia.
What is the role of viral infections in the pathogenesis of lymphoma?
Viral infections such as Epstein-Barr, herpesvirus-8, bovine leukemia virus, and feline leukemia virus are well-recognized in other species, but not confirmed in horses.
What diagnostic techniques are used for lymphoma?
Histologic evaluation of biopsy tissues, cytologic examination of fine needle aspirates, imprint tissue smears, and fluid samples.
