Diagnose the Abdominal Mass in This Dog
Read this presenting complaint and history below, evaluate the slides and make your diagnosis.
Presenting Complaint and History
An 11-year-old male neutered Golden Retriever mix was presented to the MedVet Mandeville Internal Medicine team with a history of a single bout of vomiting. An abdominal ultrasound revealed four mixed echogenic masses in the left and right abdomen, which did not have any appreciable connection to specific organs.
The largest mass measured approximately 5.6 cm x 6.6 cm. The spleen was absent, and the owners noted that it had been removed three years previously. Fine-needle aspiration of the largest mass revealed extramedullary hematopoiesis with several lymphoid elements.
Read the following slides and make your diagnosis:
Figure 1. Highly cellular sample containing capillaries (black arrow) and megakaryocytes (red arrow). Wright-Giemsa stain. 100x magnification.
Figure 2. Late erythroid precursors (black arrowhead) and a plasma cell (blue arrow). Wright-Giemsa stain. 500x magnification.
Figure 3. Many mitotic figures (red arrowhead indicates a cell in anaphase of mitosis) were present. Wright-Giemsa stain. 1000x magnification.
Figure 4. Erythroid (black arrowheads) and myeloid (blue arrowhead) precursors with a plasma cell (blue arrow. Wright-Giemsa stain. 500x magnification.
Diagnosis: Splenosis
Based on these findings, the mass was interpreted to represent splenic tissue growth due to seeding during the surgical procedure. Myelolipoma was also considered as a potential differential diagnosis; however, the lack of adipocytes or any obvious lipid material made this less likely.
Splenosis in dogs has been reported within the mesentery and as embedded nodules within organ parenchyma. While not typically considered malignant, there have been rare reports of replacement of normal organ tissue (hepatic parenchyma) with this ectopic splenic tissue, which resulted in compression atrophy of normal hepatocytes. Additionally, this ectopic splenic tissue may be more susceptible to traumatic rupture leading to pain and hemorrhage for the patient.
