Benign ectopic splenic tissue mimicked cancer in a dog
Bottom line
A new case report in Veterinary Radiology & Ultrasound describes a 14-year-old dog with a prior splenectomy that presented with hyporexia and vomiting, then was found on imaging to have multiple cavitated abdominal masses that looked concerning for malignant neoplasia. Instead, histopathology showed benign ectopic splenic tissue with hematoma formation, reinforcing that splenic implants or accessory splenic tissue can closely mimic cancer in dogs after splenic surgery or splenic injury. The report adds to a small but growing veterinary literature showing that ectopic splenic tissue can appear years after splenectomy and can be mistaken for metastatic or primary abdominal malignancy on imaging alone. (acvs.org)
Why it matters: For veterinary teams, the case is a reminder to keep ectopic splenic tissue on the differential list when older dogs with a history of splenectomy develop abdominal nodules or cavitated masses. That matters because splenic masses in dogs are often approached with a high index of suspicion for malignancy, and ACVS notes that up to two-thirds of splenic masses are malignant, with hemangiosarcoma a common concern, but benign lesions can look similar clinically and on imaging. In dogs with prior splenic rupture or splenectomy, anchoring too quickly on cancer could shape staging, surgical planning, and conversations with pet parents before tissue diagnosis is available. (acvs.org)
What to watch: Expect this case to sharpen discussion around when prior splenectomy history should more strongly influence radiology reports, surgical decision-making, and recommendations for histopathologic confirmation.
Key facts
- Study type
- Case report
- Journal
- Veterinary Radiology & Ultrasound
- Patient
- 14-year-old dog
- History
- Prior splenectomy
- Presenting signs
- Hyporexia and vomiting
- Imaging finding
- Multiple cavitated abdominal masses
- Initial concern
- Malignant neoplasia
- Final diagnosis
- Benign ectopic splenic tissue with hematoma formation
- Clinical takeaway
- Ectopic splenic tissue can mimic metastatic or primary abdominal malignancy after splenic surgery or injury
A case report in Veterinary Radiology & Ultrasound highlights an uncommon but clinically important diagnostic pitfall: a 14-year-old dog with a previous splenectomy developed multiple abdominal masses that appeared consistent with malignant neoplasia on imaging, but the lesions were ultimately confirmed as benign ectopic splenic tissue with hematoma formation. The case underscores how convincingly ectopic splenic tissue can imitate cancer in dogs, particularly when the lesions are multiple, cavitated, and found in a patient with nonspecific gastrointestinal signs. (onlinelibrary.wiley.com)
The background here is familiar to many clinicians. Splenic masses in dogs often trigger urgent concern because malignant disease is common, and hemangiosarcoma remains a leading fear in older patients. ACVS says up to two-thirds of canine splenic masses are malignant, while benign lesions such as hematoma and nodular hyperplasia can present similarly and are only definitively distinguished after removal and microscopic examination. That diagnostic uncertainty helps explain why abdominal masses in a post-splenectomy dog may still be read first as possible neoplasia. (acvs.org)
What makes this report notable is that it fits into an emerging body of veterinary evidence suggesting ectopic splenic tissue may be underrecognized. A 2025 pathology review of 46 dogs found the omentum and mesentery were the most common sites for ectopic splenic tissue, and the authors argued that “ectopic splenic tissue” may be the most practical umbrella term because histologic classification as accessory spleen versus splenosis does not always match the clinical history. They also noted concurrent splenic masses in some dogs, including hemangiosarcoma in four cases, which means ectopic splenic tissue can coexist with clinically important splenic disease rather than simply replace it as a concern. (pubmed.ncbi.nlm.nih.gov)
Prior case literature points in the same direction. Earlier canine reports have described ectopic spleen or splenosis presenting as an abdominal mass after splenectomy, including a case associated with anemia and another in which ectopic spleen mimicked a hepatic tumor with intra-abdominal metastases on triple-phase CT. A 2026 Veterinary Radiology & Ultrasound report similarly described peritoneal splenosis discovered years after splenectomy, with authors noting that the imaging appearance can mimic neoplasia and that histopathology was required to confirm the absence of malignancy. (pmc.ncbi.nlm.nih.gov)
Expert reaction in the strict quote-driven sense appears limited so far, which is typical for a single case report. Still, the broader specialty literature is consistent: imaging can narrow the differential, but it may not settle it. Recent radiology work on splenic lesions in dogs has emphasized that distinguishing benign from malignant splenic pathology before surgery remains challenging, and cytology or imaging characteristics do not always produce definitive answers. In that context, this new case functions less as an outlier and more as a reminder of a known blind spot that becomes especially relevant when a dog has a history of splenic trauma or splenectomy. (onlinelibrary.wiley.com)
Why it matters: For veterinarians, the practical takeaway is not that cancer should be deprioritized, but that post-splenectomy ectopic splenic tissue deserves a place in the differential diagnosis when abdominal masses are found. That can influence how radiologists frame reports, how surgeons counsel pet parents, and how internists discuss prognosis before histology is back. It may also help reduce premature assumptions when multiple nodules are present, since multiplicity can push clinicians toward metastatic disease even though splenosis can produce multifocal implants. (pubmed.ncbi.nlm.nih.gov)
The case also has communication value. Because splenic masses are so often discussed with pet parents in the context of rupture risk, hemoabdomen, and hemangiosarcoma, a finding like this is a reminder to pair urgency with uncertainty. In select post-splenectomy patients, especially those with compatible surgical history and imaging findings, benign ectopic splenic tissue may be a plausible explanation even when the scan looks ominous. That does not eliminate the need for intervention, but it can sharpen informed consent and expectation-setting. (acvs.org)
What to watch: The next step to watch is whether future reports can define imaging patterns that more reliably distinguish ectopic splenic tissue from malignant abdominal masses before surgery, particularly in dogs with known prior splenic rupture or splenectomy. For now, tissue diagnosis remains the deciding step. (onlinelibrary.wiley.com)