Diffuse Splenomegaly

Nodular

Associated with neoplastic (tumor) or non-neoplastic disorders (infection, hyperplasia/regeneration, or inflammation).

General Comments

• Splenic enlargement-often nonspecific.
• Frequently reflects an underlying disorder rather than primary disease of the spleen.

Historical Findings

• Vomiting, diarrhea, anorexia-can be seen with infiltrative diseases such as lymphoma, mast cell tumor, FIP, lymphoplasmacytic enteritis (cats).
• Lethargy, anorexia, vomiting, vague abdominal pain (in acute cases pain can be severe), mild to moderate abdominal distention in deep-chested large- to giant-breed dogs (Great Dane, German shepherd overrepresented) -associated with splenic torsion (with or without concurrent gastric dilatation volvulus).
• Weakness, lethargy, collapse (can be episodic), abdominal distention-can indicate a hemoabdomen secondary to hemangiosarcoma, bleeding/ruptured spleen from other neoplasia (rare) or benign conditions such as a hematoma.

Physical Examination Findings

• Prominent spleen on abdominal palpation or cranial/midabdominal mass; non-palpable spleen does not preclude splenomegaly.
• Dogs-smooth or irregular surface.
• Cats-usually diffuse, uniform enlargement.
• Pallor, poor capillary refill time, poor peripheral pulses and tachycardia if splenic hemorrhage or splenic torsion.
• Abdominal distention if massive splenomegaly or splenic rupture (effusion).
• Petechia and ecchymosis if coagulopathy secondary to primary splenic disorder or underlying disease.
• Concurrent hepatomegaly, thickened intestines, and/or mesenteric lymphadenopathy imply infiltrative or inflammatory disease.
• Peripheral lymphadenomegaly-suggests lymphoma/leukemia.
• Cardiac arrhythmias-may indicate clinically significant cardiac abnormality affecting the spleen (congestion) but ventricular arrhythmias also are associated with primary splenic disorders.

Dogs

Cats

Dogs

• Regenerative anemia secondary to splenic bleeding or hemolytic disease.
• Nucleated RBC-may accompany EMH, indicates splenic dysfunction.
• Spherocytes-hemolysis, microangiopathic shearing (schistocytes also).
• Leukocytosis with a left shift-may indicate infectious or inflammatory conditions, marked regenerative response, or EMH.
• Thrombocytopenia-from increased consumption (DIC or bleeding) secondary to hemangiosarcoma or other neoplasia, increased destruction (immune-mediated), sequestration, or decreased production in the bone marrow.
• Hypercalcemia may be associated with neoplasia, especially lymphoma.
• Hyperglobulinemia may be associated with neoplasia or Ehrlichia infections.
• Hemoglobinemia and hyperbilirubinemia-may occur with microangiopathic anemia, splenic torsion, hemangiosarcoma, and immune-mediated anemia with spleen as site of extravascular RBC removal.

Cats

• Direct RBC examination for hemoparasites.
• Regenerative anemia and splenomegaly-may indicate hemotropic mycoplasmosis.
• Macrocytosis and nonregenerative anemia-suggests retroviral infection or myeloproliferative disease.
• Eosinophilia-suggests hypereosinophilic syndrome, systemic mastocytosis, or lymphoma.
• Circulating blast cells-suggest myeloproliferative or lymphoproliferative disorder.
• Nucleated RBCs-may accompany EMH and splenic dysfunction.
• Thrombocytopenia-from increased consumption (DIC), increased destruction (immune-mediated), sequestration, or decreased production in the bone marrow.

Abdominal Radiography

• Confirms or detects splenomegaly.
• Mass effect may appear in the left midcranial abdomen.
• May provide evidence of an underlying cause-concurrent hepatomegaly may indicate infiltrative disease or right-sided heart disease; splenic torsion may occur secondary to gastric dilation or volvulus.
• Effusion-may indicate hemorrhage from splenic rupture (hemangiosarcoma, hematoma) or portal hypertension influencing splenic perfusion. Visualization of the splenic tail along the ventral body wall on lateral radiographs of cats supports the diagnosis of splenomegaly.

Thoracic Radiography

• Three views (right and left lateral and dorsal-ventral views)-screen for metastasis and underlying disease in thoracic cavity and effusion.
• Evaluate sternal lymph nodes-these drain the abdominal cavity, reflecting disorders causing lymphadenomegaly. Evaluate for signs of congestive heart failure (size of the cardiac silhouette and pulmonary veins and evidence of pulmonary edema or pleural effusion).

Abdominal Ultrasonography

• Distinguishes between diffuse and nodular parenchymal patterns; nodular abnormalities easily identified.
• Diffuse enlargement with normal parenchyma-may occur with congestion or cellular infiltration.
• Hypoechogenicity-may occur with splenic torsion, splenic vein thrombosis, lymphoma, or leukemia.
• Complex, mixed echogenic mass-hemangiosarcoma or hematoma.
• Hematomas-variable echogenicity; may have internal septation and encapsulation and pass through a stage where they resemble target lesions suggesting neoplasia.
• Can identify concurrent abdominal diseases-liver, kidneys, intestines, and lymph nodes.
• Cannot differentiate between benign and malignant splenic disorders.
• Doppler color flow interrogation of splenic vasculature may detect splenic vein thrombi or splenic torsion.

Echocardiography

Evaluation of right atrium for mass lesions-when hemangiosarcoma suspected (based on ultrasonographic appearance and hematology) or to determine if there is cardiac disease causing splenic congestion.

Fine-Needle Aspiration

• Assess coagulation status before any aspiration. Procedure-patient in right lateral or dorsal recumbency; use a 23- or 25-gauge, 2.5–3.75 cm (1–1.5 in.) length needle; using ultrasound guidance.
• Non-aspiration method (when negative pressure is NOT applied to the syringe) results in higher yield of nucleated cells relative to the amount of blood than aspiration method.
• Specimens-evaluate cytologically for infectious agents (often found in macrophages); identify predominant inflammatory or infiltrative cell type.
• Neoplastic infiltrates-classified as epithelial, mesenchymal, or discrete (round cell).
• Aspiration of cavitated masses may cause rupture and is not recommended.

Bone Marrow Aspiration

• Indicated with cytopenias before splenectomy (spleen may be supporting hematopoiesis).
• May yield an infectious disorder (e.g., ehrlichiosis, mycosis, toxoplasmosis, leishmaniasis) or hematopoietic neoplasia.

Splenectomy

• With anemia or leukopenia-rule out bone marrow aplasia/hypoplasia before surgery; spleen may be the source of hematopoiesis.
• Indicated for splenic torsion, splenic rupture, isolated splenic masses considered likely to be neoplastic, and mast cell infiltration (cats).
• Exploratory laparotomy-permits direct evaluation of all abdominal organs.