This scenario is a common one and frequently seen in small animal practice; It typically involves an older, large breed dog that presents with a vague history of a loss or decrease in appetite, weakness, lethargy, and sometimes vomiting is also reported. An emergency visit may be prompted by an acute collapse of the animal. A detailed history and physical examination are critical for determining next steps.
Trauma can be quickly ruled out for the shocky or recumbent patient based on the history and a cursory examination of the dog. Hemoabdomen associated with a bleeding intra-abdominal mass is an important differential diagnosis for dogs presenting with concurrent physical examination findings that include abdominal distention, a palpable abdominal mass, pale oral mucous membranes, and other findings consistent with shock.
A presumed diagnosis can be confirmed by performing point-of-care assessments including imaging (abdominal radiography or sonography (abdominal focused assessment with sonography for trauma (A-FAST)), and lab tests including packed cell volume, total plasma protein (PCV / TP), a platelet count, and coagulation testing (PT / aPTT). An abdominocentesis that yields a bloody effusion is confirmatory of hemoabdomen. Surgery for this animal is typically indicated to remove the source of active hemorrhage - the diseased intra-abdominal organ and the associated bleeding mass.
Historically, hemangiosarcoma (HSA) - a malignant cancer that carries a poor long-term prognosis - is the most common diagnosis in these patients with nontraumatic hemoabdomen associated with a splenic mass (upwards to 70% of the cases). When presented with the broad probability of a poor prognosis along with the cost estimate for surgery and care required for these patients, some owners elect euthanasia and decline further treatment. Furthermore, they are often faced with having to make this decision fairly quickly. The conundrum for all involved is trying to determine whether an individual patient may actually have benign disease, which - presumably - would be curative and confer a better prognosis for survival.
Can we predict who will have benign vs. malignant disease before going to surgery?
There are two tools available to veterinarians that can assist them in predicting whether an individual dog has a greater likelihood (or not) of having a benign versus malignant splenic mass in cases of nontraumatic hemoabdomen. Information provided by these two tools can help to guide veterinarians and pet owners in deciding a best course of action for an individual patient. Many folks, after all, might elect treatment and surgery for their dog if there was a greater likelihood of those efforts being curative (as one would expect for patients with benign disease). These two tools are the HeLP score and the T-STAT decision-support calculator.
The HeLP score
The HeLP (hemangiosarcoma likelihood prediction) score considers 4 variables for predicting the risk for hemangiosarcoma in dogs with nontraumatic hemobadomen. These factors include:
- patient body weight (kg)
- total plasma protein (g/dl) as measured by a handheld refractometer
- platelet count
- findings of thoracic radiographs
Using these parameters, a given patient will be assigned a score of 0-100 and categorized as having a low, medium, or high risk for the probability of a hemangiosarcoma diagnosis. Scoring interpretation is as follows:
A score of 0-40 = low risk (36% probability of HSA diagnosis)
A score of 40-55 = medium risk (75.7% probability of HSA diagnosis)
A score of >55 = high risk (95.7% probability of HSA diagnosis)
The HeLP score is described further in this publication: Development and validation of a hemangiosarcoma likelihood prediction model in dogs presenting with spontaneous hemoabdomen: The HeLP score by Schick, Hayes, Singh et. al. in J Vet Emerg Crit Care. 2019;29:239–245
The T-STAT
We recently reported on a new decision-support calculator called the T-STAT. As Dr. John Berg, DVM, MS, DACVS explained, this online tool considers 8 different clinical variables to estimate the relative probability of splenic malignancy. These variables include: serum total protein, the presence of >2 nucleated RBCs (nRBC) / 100 WBCs, splenic mass diameter (as measured on abdominal ultrasound), the presence of / number of liver nodules, splenic masses or nodules, and mesenteric / omental / peritoneal nodules, the degree of splenic mass inhomogeneity (as determined on ultrasound), and the degree of abdominal effusion. You can learn more about the T-STAT from Dr. John Berg in this specialty update.
While both of these tools are helpful to veterinarians and pet owners in assessing an individual dog's relative risk for malignant disease, a decision to euthanize a patient should not be recommended based solely on the scores determined by either of these tools. There are many other things to consider including patient-related factors and those of the pet's family and caregivers
The patient has surgery ... now what?
Surgery to remove the diseased organ and associated mass (e.g. splenectomy in the case of a bleeding splenic mass) is the treatment of choice for stabilizing the patient and can be lifesaving in the short term. Patients diagnosed with a malignancy on histopathology generally carry a poor prognosis. Published reports indicate the median survival time for dogs with splenic hemangiosarcoma is as short as a couple of months (65 days1 or 68 days2) or longer with adjuvant treatment with chemotherapy (117 to 277 days3-11).
It is important to keep in mind that there are other tumor types that could be determined on histopathology. They typically carry a better prognosis than that for hemangiosarcoma and include cancers involving the liver (e.g. hepatocellular carcinoma, hepatoma) or other tumors affecting the spleen (e.g. lymphoma, histiocytic or nonendothelial sarcoma). A diagnosis of a splenic hematoma is the most common of the benign / non-neoplastic possibilities for masses involving the spleen. Other benign findings can include benign nodular hyperplasia, lymphoid hyperplasia, and extramedullary hematopoiesis.
Biopsies, diagnoses, and expectations ...
Have you ever experienced this situation? You receive a tissue biopsy report that indicates the presence of a "malignancy," the owner is told that the dog "has 'x number' of months to live" (based on the best evidence that is available), and then that animal is still alive many months or years later? It can and does happen. The opposite scenario can also play out, whereby an animal is diagnosed with a "benign" mass and then deteriorates or dies sooner than expected due to the development of metastases or recurrence of the cancer.
There are several plausible explanations for these phenomena. Misdiagnoses can be made. A pathologist may assign an incorrect diagnosis - not due to incompetence, but rather they had to make a determination and assign a diagnosis for a disease state that was not so clear cut and easily distinguishable (i.e. benign from malignant). Hemangiosarcoma, as an example, is one of those tumor types that can be difficult to differentiate from a splenic rupture, hematoma or hemangioma (benign conditions). In the case of splenic masses, there can be a compounded situation or coexistence of malignant cells that are surrounded by other areas of diseased but benign, ruptured hematomas. Depending on where the pathologist samples the large organ, the malignancy could be missed altogether. With regard to hemangiosarcoma, a study published in 2016 found that 13% of animals diagnosed with benign splenic masses subsequently developed hemangiosarcoma.12 It's certainly possible that these animals developed a new problem (malignancy) down the road, but it more strongly suggests that upwards to 13% of the cases may have been misdiagnosed at the onset. In light of these challenges for pathologists, and in an effort to improve the likelihood of making a correct diagnosis, clinicians should submit the entire spleen for histopathology after splenectomy (as opposed to submitting the suspected mass alone), and pathologists should sample and examine a minimum of 5 different areas of that specimen to arrive at their diagnosis13.
So, let's say you receive a "benign" histopath report. There is a sigh of relief when the biopsy report indicates a non-malignant, benign finding. Assuming the patient is in good health otherwise, one would assume or expect that the dog would go on and live a "normal" lifespan. We know that this does not always play out in that fashion. As stated previously, some animals may go on to "develop" a malignant cancer. Another study14 was recently published by a group out of Colorado State University regarding the incidence of premature death in dogs after splenectomy for nontraumatic hemoabdomen, and who had received a "benign" histopathologic diagnosis. One of the investigators involved in that study - Dr. Kristin Zersen, DVM, DACVECC - recently spoke to us about their findings. Her discussion provides us with a better understanding of this phenomenon, as well as some helpful talking points and considerations for veterinary professionals when advising pet owners of their options and expectations. View this On Demand (running time: 26 mins).
References:
1. Robertson JL, Newman SJ. Disorders of the spleen. In: Feldman BF, Zinkl JG, Jain NC, eds. Schalm's Veterinary Hematology, 5th ed. Balti- more, MD: Lippincott Williams & Wilkins; 2000:272.
2. Schick AR, Hayes GM, Ameet S, Mathews KG, Higginbotham ML, Sherwood JM. Development and validation of a hemangiosarcoma likelihood prediction model in dogs presenting with spontaneous hemoabdomen: The HeLP score. J Vet Emerg Crit Care. 2019;29:239–245.
3. Kim SE, Liptak JM, Gall TT, et al. Epirubicin in the adjuvant treatment of splenic hemangiosarcoma in dogs: 59 cases (1997–2004). J Am Vet Med Assoc 2007;231:1550–1557.
4. Vail DM, MacEwen EG, Kurzman ID, et al. Liposome-encapsu- lated muramyl tripeptide phosphtidylethanolamine adjuvant immunotherapy for splenic hemangiosarcoma in the dog: a randomized multi-institutional clinical trial. Clin Cancer Res 1995;1:1165–1170.
5. Hammer AS, Couto CG, Filppi J, et al. Efficacy and toxicity of VAC chemotherapy (vincristine, doxorubicin and cyclophos- phamide) in dogs with hemangiosarcoma. J Vet Intern Med 1991;5:160–166.
6. Sorenmo KU, Baez JL, Clifford CA, et al. Efficacy and toxicity of a dose-intensified doxorubicin protocol in canine heman- giosarcoma. J Vet Intern Med 2004;18:209–213.
7. Ogilvie GK, Powers BE, Mallinckrodt CH, et al. Surgery and doxorubicin in dogs with hemangiosarcoma. J Vet Intern Med 1996;10:379–384.
8. Wood CA, Moore AS, Gliatto JM, et al. Prognosis for dogs with stage I or II splenic hemangiosarcoma treated by sple- nectomy alone: 32 cases (1991–1993). J Am Anim Hosp Assoc 1998;34:417–421.
9. Payne SE, Rassnick KM, Northrup NC, et al. Treatment of vascular and soft-tissue sarcomas in dogs using an alternat- ing protocol of ifosfamide and doxorubicin. Vet Comp Oncol 2003;1:171–179.
10. Prymak C, McKee LJ, Goldschmidt MH, et al. Epidemiologic, clinical, pathologic, and prognostic characteristics of splenic hemangiosarcoma and splenic hematoma in dogs: 217 cases (1985). J Am Vet Med Assoc 1988;193:706–712.
11. Wendelburg KM, Price LL, Burgess KE, et al. Survival time of dogs with splenic hemangiosarcoma treated by splenec- tomy with or without adjunctive chemotherapy: 208 cases (2001–2012). J Am Vet Med Assoc 2015;247:393–403.
12. Patten, SG, Boston, SE, Monteith, GJ. Outcome and prognostic factors for dogs with a histological diagnosis of splenic hematoma following splenectomy: 35 cases (2001–2013). Can Vet J. 2016;57(8):842–846.
13. Herman EJ, Stern AW, Fox RJ, Dark MJ. Understanding the Efficiency of Splenic Hemangiosarcoma Diagnosis Using Monte Carlo Simulations. Veterinary Pathology. 2019;56(6):856-859.
14. Millar SL, Curley TL, Monnet EL, Zersen KM. Premature death in dogs with nontraumatic hemoabdomen and splenectomy with benign histopathologic findings. J Am Vet Med Assoc. 2021 Dec 15;260(S1):S9-S14
