GENERAL CONSIDERATIONS
+ Biologic Behavior
- HSA is a highly metastatic tumor with microscopic or macroscopic metastatic disease at diagnosis
- HSA arises from vascular endothelial cells
- HSA is the 4th most common splenic tumor in cats
- Median age 8-10 years
- Sex predisposition: males
- No breed predisposition
- Splenic HSA is highly metastatic (60%) with sites including lungs, liver, regional lymph node, mesentery, and brain
+ Clinical Signs
- Non-specific
- Acute Presentation: acute dyspnea, pallor, abdominal effusion, and hypovolemic shock secondary to splenic rupture and hemorrhage
- Chronic Presentation: lethargy, anorexia, and weight loss
+ Physical Examination
- Palpable abdominal mass with splenomegaly and abdominal fluid wave
- Cardiac abnormalities: arrhythmia, cardiac murmur, and muffled heart sounds
Diagnosis
+ General Considerations
Splenic HSA and hemangioma have similar ultrasonographic and gross appearance and are difficult to differentiate
+ Laboratory Findings
- Hematology: anemia and morphological changes to red blood cells such as nucleated erythrocytes, polychromasia, poikilocytes, anisocytes, shistocytes, and reticulocytes
- Morphologic changes due to iron loss, altered hepatic lipoprotein metabolism, microangiopathic disease, or DIC and sluggish flow through abnormal vascular channels resulting in increased membrane fragility
- Neutrophilic leukocytosis is common due to either stress or tumor rupture and necrosis
- Thrombocytopenia due to DIC, but may form part of Kasabach-Merritt syndrome
- Kasabach-Merritt syndrome is characterized by an enlarging vascular tumor, thrombocytopenia, anemia, prolonged PT and APTT, decreased FDP, and increased fibrin split products
- Thrombocytopenia (75%-90%), fragmented red blood cells (80%), and DIC (50%) are common findings
- Anemia and DIC associated with blood loss is common in cats with visceral HSA
+ Survey Radiographs
- 2 metastatic patterns in dogs with HSA:
- Widely disseminated nodular pattern (common)
- Diffuse interstitial pattern (uncommon)
- False-negative results are high: 22% from splenic HSA and > 50% for right atrial HSA
+ Ultrasonography
- Abdominal ultrasonography is a highly accurate and sensitive tool for splenic evaluation
- Primary HSA: mixed pattern of anechoic and hyperechoic regions
- Metastatic HSA: diffusely anechoic or hypoechoic appearance
- Ultrasound-guided FNA or needle-core biopsy contraindicated due to risk of seeding and low diagnostic yield
+ Electrocardiography
Ventricular arrhythmias are commonly associated with HSA due to hypoxia, anemia, or hypovolemia
TREATMENT
+ Surgical Management
- Total splenectomy recommended
+ Chemotherapy
- Doxorubicin 30 mg/m2 q 2-3 weeks for 5 doses
- ± cyclophosphamide 100-150 mg/m2
- Complications: neutropenia (common), severe gastroenteritis, cardiotoxicity, and sepsis
+ Prognosis
- Mean ST 22 weeks
- 100% metastatic rate
SPLENIC HEMANGIOSARCOMA
| T0 | No evidence of neoplasia |
| T1 | Tumor less than 5 cm in diameter and confined to primary site - Primary Tumor |
| T2 | Tumor ≥ 5 cm in diameter, ruptured, or invading subcutaneous tissue |
| T3 | Tumor invading adjacent structures including muscle |
| M0 | No evidence of metastasis |
| M1 | Evidence of distant metastasis with site specified - Metastasis |
| N0 | No evidence of regional lymph node involvement |
| N1 | Regional lymph node involvement - Node |
| N2 | Distant lymph node involvement |