Ectopic splenic tissue in 46 dogs, 2000-2024.

Area of Science:

• Veterinary Pathology
• Canine Histology
• Surgical Pathology

Background:

• Ectopic splenic tissue, such as accessory spleens and splenosis, presents as nodules outside the main spleen.
• Distinguishing between accessory spleens (congenital) and splenosis (acquired) is complex in domestic animals, with terms often used interchangeably.
• Accurate differentiation is vital due to potential concurrent splenic lesions, including hemangiosarcoma.

Purpose of the Study:

• To evaluate ectopic splenic tissue diagnoses in canine surgical biopsies.
• To assess the correlation between original and updated histologic diagnoses.
• To determine the utility of the term "ectopic splenic tissue" for canine lesions.

Main Methods:

• Review of 46 canine surgical biopsy specimens diagnosed with ectopic splenic tissue from 2000-2024.
• Histologic assessment focusing on fibrous capsule, smooth muscle trabeculae, and pulp architecture.
• Comparison of original diagnoses (accessory spleen, splenosis) with updated diagnoses based on histologic findings.

Main Results:

• The omentum and mesentery were the most common locations for ectopic splenic tissue.
• Updated diagnoses favored accessory spleen (37 cases) over splenosis (9 cases) after histologic review.
• Histologic diagnosis did not always correlate with clinical history or gross findings, supporting the use of "ectopic splenic tissue" as a broader term.

Conclusions:

• Histologic evaluation is essential for accurate diagnosis of ectopic splenic tissue in dogs.
• The term "ectopic splenic tissue" is recommended as a more inclusive descriptor for these lesions.
• Differentiating ectopic splenic tissue from splenic masses like hemangiosarcoma is critical for patient management.