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Spleen masses-dogs

Benign disease is more common



1) malignancy of vascular endothelial cells
2) 2% canine cancer
3) higher incidence in German shepherds, golden retrievers, labradors
4) arises anywhere: most common is skin, subcutaneous, spleen, liver, and right atrium or auricle
5) synchronous disease-multiple primary sites
6) biological behavior aggressive in all forms except superficial epidermal form
7) 2/3 splenic masses are malignant, 2/3 HSA
8) suspicion of spleen HSA: splenomegaly and anemia, hemoabdomen, increased nRBC


HSA spleen presenting signs

1) Nonspecific-lethargy, anorexia, weakness, weight loss
2) Specific signs: acute weakness, sudden collapse/death, exercise intolerance, abdominal effusion/mass, hypovolemic shock
3) weakness and abdominal distention may wax/wane
4) regenerative anemia, increased nucleated RBC, polychromasia, thrombocytopenia
5) up to 1/3 dogs with spleen HSA have subclinical DIC*


Diagnosis of HSA

1) ultrasound-guided FNA may be dangerous if cavitated
2) coagulation panel
3) abdominal or pericardial tap, cytology, PCV
-blood from hemoabdomen shouldn't clot


Traditional therapy: HSA

1) surgical excision: splenectomy, right atrial appendage removal, subcutaneous mass excision
2) 1/3 of dogs with spleen HSA have arrhythmias
3) no patient should be euthanized because of hemoabdomen alone-histopathology needed to confirm
4) cardiac troponin I concentration allows differentiation of cardiac HSA from HSA at other locations


Survival after splenectomy

1) approximately 1-3 months survival with surgery alone (splenectomy)
2) systemic therapy-chemotherapy with doxorubicin
- approximately 6 months survival time

Note: it's a surgical disease ==> we want to remove the tumor



1) doxorubicin postop for any location will improve survival!
2) poor prognosis: cardiac mass, collapse, hemoabdomen*, advanced clinical stage, multiple nodules


2 skin presentations

1) thin haired regions: solar induced inguinal/abdomen
-strawberry like lesion, multiple, diffuse
2) cutaneous prepucial, abdomen
-postsurgical MST 2 years of superficial (dermal)
3) if deeper, subcutaneous tissues, then 4-10 months
-chemotherapy increases survival



1) in cats, mast cell tumor and lymphoma are common malignant causes of diffuse splenomegaly
2) spleen masses may be hemangiosarcoma or similar DDX as dogs
3) skin HSA: UV induced-metastasis uncommon, locally recurrent
-if not caused by solar exposure and no metastasis, then aggressive surgery



Tumor growth is halted when malignant cells are located more than 100-200 um from blood vessels, which is the limit for diffusion of oxygen*


Chemotherapy for anti-angiogenesis

1)**ultra low dose, daily chemotherapy (metronomic)
-inhibits vascularization of islands of tumor cells
-dose is too low to damage the actual tumor cells
-much less potential toxicity!
-The tumor might be resistant to high-dose chemo, but we might be able to inhibit metastasis!


Metronomic chemotherapy

1) low dose cyclophosphamide and piroxicam
-decreases circulating endothelial progenitor cells
-increases anti-angiogenesis factors
2) no survival advantage when compared with doxorubicin given post splenectomy


Spleen masses-dog

1) benign disease is more common: hematoma, hyperplastic nodule, abscess, extra medullary hematopoiesis, granuloma in more than 50%
2) primary spleen tumors: hemangiosarcoma, fibrosis, histiocytic sarcoma, leiomyosarcoma, hemangioma, osteosarcoma