Monthly Update
Editor: William B Henry DVM, DACVS
Issue Contributors: William B. Henry DVM, DACVS;
Catherine Reese DVM, DACVS; Louisa Rahilly DVM, DACVECC

April 2012
SPLENIC MASS MYTH: THE MAJORITY OF SPLENIC MASSES ARE SPLENIC HEMANGIOSARCOMAS (SHS)   


There are four studies answering that question. The first is an older study done in 1985 at the University of Pennsylvania School of Veterinary Medicine.This manuscript reported the histopathology of 217 surgical specimens following splenectomy.1  Ninety two dogs had SHS and one hundred and twenty five had splenic hematomas (hematomas were not differentiated from benign hemangiomas).1 Thus 42% were SHS and 58% were benign. In that study hemoperitoneum was significantly more common in dogs with SHS  P<0.001).1  German Shepherds were the most commonly affected breed.1  In the second, more recent study 65 splenic mass cases were examined between 2007-2008 in a private surgical referral practice.2  Thirty dogs (46%) had SHS.2  Ten dogs (15%) had other types of malignant tumors: 2 with liposarcoma, 2 with pleomorphic sarcoma, 1 with a fibrohistocytic nodule, 1 with myxosarcoma, 1 with marginal cell sarcoma, and 3 with spindle cell sarcoma).2 Twenty five dogs (38%)  had benign masses (4 nodular hyperplasias, 20 hematomas, 1 splenic infarct and hematoma formation).2 Hemoperitoneum was present in 24 of the 30 dogs (80%) of dogs with SHS, 14 of 25 (56%)  the dogs with benign masses, and 2 of 10 (20%) the dogs with malignant masses other than SHS. Thus in this study there was a significant difference in the prevalence of hemoperitoneum between dogs with SHS and dogs with benign masses ( P=0.05).2  German Shepherds were the most commonly affected breed followed by Labrador Retrievers and Golden Retrievers.2  Dogs with benign splenic masses  have a significantly higher splenic weight as a percentage of body weight than dogs with SHS.2  In a third study, 241 of 500 splenic were malignant, 48%.3 In the fourth study, 59 of 100 (59%) splenic masses were malignant, and 43 of the 59 (73%)  were SHS.4
 
IN THESE FOUR PAPERS THE AVERAGE NUMBER OF SPLENIC MASSES THAT WERE MALIGNANT  WAS  51.25% AND 47.25 WERE BENIGN. The take home numbers to remember when rounded off is 50/50 benign vs. malignant.
 
PREOPERATIVE DETERMINATION OF MALIGNANT vs. BENIGN SPLENIC MASSES PAST AND PRESENT
 
The distinction between benign and malignant splenic masses  is important because of the poor prognosis for dogs with splenic SHS. Dogs with Stage 1 and Stage 2 splenic SHS had a mean survival time of 86 days.5   Noninvasive methods that can be used to differentiate benign from malignant splenic masses  are 1) plain radiographs using the standard two abdominal views for splenic mass size and hemoperitoneum, 2) the standard three thoracic radiographs for visible metastatic lung disease, 3) ultrasonography,  4) abdominal centesis  for evidence of hemoperitoneum and cell cytology, 5) clinical pathology findings and 6) Computed Tomography (CT).
 
PLAIN RADIOGRAPHS are of value in determining the presence of large splenic masses and large volume hemoperitoneum, but very innaccurate in diagnosing metastatic lung disease. Direct digital radiography (DR) with high resolution monitor screens and black on white contrast may help in lung metastatic disease evaluation. However, direct DR is often only found in referral practices.
 
ULTRASONOGRAPHY is helpful in determining splenic mass location and size as well as hemoperitoneum, but inaccurate in determining abdominal organ metastatic disease. Two recent publications found that using contrast enhanced ultrasonographic  determination of benign vs. malignant splenic disease may be more accurate than plain ultrasound exams. These, however, require specialists in radiology and /or internal medicine and the appropriate dye.6,7
 
ABDOMINAL CENTESIS for evidence of hemoperitoneum and cytologic exam via splenic fine needle aspiration (FNA) is a practical method of differentiating malignant from benign splenic masses, but in a previous study the cytologic exam of splenic masses agreed with the histologic diagnosis only 61.3 % of the time. 8
 
CLINICAL PATHOLOGIC findings that have been reported as useful for the diagnosis of malignant vs. benign splenic masses in dogs include the combination of anemia, thrombocytopenia, and abnormal RBC morphology at the time of examination.2  A  combination of hemoperitoneum, low total solids concentration, and a low platlet count9 ; and a combination of anemia, splenic rupture, and splenomegaly.2  These clinical findings are suggestive, but not definitive.
 
COMPUPUTED TOMOGRAPHY (CT) is considered the most accurate method of determining lung metastasis in human medicine today.  This is true in veterinary medicine as well. This month's CT Corner demonstrates its use in metastatic splenic hemangiosarcoma in a dog.  IN THE ABSENCE OF LUNG METASTASIS ON CT, ABDOMINAL CT IS THE MOST ACCURATE PREOPERATIVE METHOD TO DETERMINE THE PRESENCE OF MALIGNANT SPLENIC vs. BENIGN SPLENIC MASSES. (See abstract in side bar.)  
 
 ANOTHER SPLENIC MASS MYTH: SPLENIC MASS SURGERY IS A ROUTINE SURGICAL PROCEDURE
 
Splenic mass surgery is not routine nor is the post-op patient care. These dogs are usually 8-12 years old, often anemic, thrombocytopenic, hypoproteinemic, and prone to ventricular arrhythmias peri-operatively.10  One should be prepared for complications under anesthesia including hypotension, cardiac arrhythmias and anemia which is unmasked by fluid therapy. Blood products may be required intra-operatively if hemorrhage occurred into the abdominal cavity or the mass itself prior to surgery.  One should prepare cautiously for anesthesia with careful consideration for close monitoring and assurance that personnel are available for aggressive treatment as needed for complications.  Following surgery, close monitoring for arrhythmias and hypotension is necessary. If the dog suffered from a hemorrhagic shock event, there is often a period of renal or splanchnic ischemia.11  Splanchnic ischemia can lead to ischemia/reperfusion injury resulting in lung injury, organ dysfunction and a clinical scenario of distributive shock following correction of the initial hypovolemia.12 Renal ischemia can lead to acid/ base and electrolyte abnormalities.  As such, these cases can have rapid changes in clinical status post operatively and require close monitoring with a doctor available to handle life threatening sequelae such as cardiac dysfunction, hypotension, lung or other organ dysfunction and disseminated intravascular coagulopathy.   

Works Cited
1  Prymak C.  et al. Epidemiologic, clinical, pathologic, and prognostic characteristics of splenic hemangisarcoma and splenic hematoma. JAVMA Vol. 193. No.6 September 15, 1988.
2 Mallinckrodt, MJ et al. Mass-to-splenic volume ratio and splenic weight as a percentage of body weight in dogs with malignant and benign splenic masses: 65 cases (2007-2008). JAVMA , Vil. 239, No. 10, November 15, 2011.
3  Spangler WL, et al. Patholgic factors affecting postsplenectomy survival in dogs. J .Vet. Intern Med.1997; 11: 166-171.
4 Johnson  KA et al Splenomegaly in dogs, predictors of neoplasias and survival after splenectomy. J.Vet. Intern. Med. 1989; 3:160-166.
5  Wood et al Prognosis for dogs with Stage 1 and 2 splenic hemangiosarcoma treated by splenectomy alone: 32 cases 9 1991-1993).JAAHA 1998; 34:417-421.
6  Rossi F. et al Use of contrast-enhanced ultrasound for characterization of focal splenic  lesions. Vet.  Radiol Ultrasound. 2008 Mar.-Apr; 49 (2):154-164.
7  Taeymans et al Contrast enhanced sonographic assessment of feeding vessels as a discriminator between malignant vs. benign focal splenic lesions. Vet. Radiol. Ultrasound. 2011 Jul.-Aug.; 52 (4) : 457-461.
8  O'Keefe et al Fine needle aspiration of the spleen as an aid in the diagnosis of splenomegaly. J. Vet. Int Med. 1987; 1: 102-109
.9  Hammond, TN et al Prevalence of hemangiosarcoma in anemic dogs with splenic mass and hemoperitoneum requiring transfusion: 71 cases ( 2003-2005 0. JAVMA 2008; 232 : 553-558
10  Marino, DJ et al Ventricular arrhythmias In dogs undergoing splenectomy: a prospective study. Vet. Surg. 1994 Mar.=Apr. 23 (2) : 101-106.
11  Muir, W.   Trauma: physiology, pathophysiology, and clinical implications.  JVECC 2006;  16(4): 253-263.
12  Diebel, LN et al.  Systemic, not just mesenteric lymph causes neutrophil priming after hemorrhagic shock. J Truama. June 2009; 66(6): 1625-31.

NEVOG News

Canine Splenic Hemangiosarcoma

Andy Abbo DVM, MS, DACVIM (Oncology)

New England Veterinary Oncology Group

  

Canine hemangiosarcoma ( HSA) is a biologically aggressive, neoplasm of vascular endothelial cells. It is estimated that HSA accounts for ~ 5-7% of all tumors seen in pet dogs. The lifetime risk of development of this cancer in dogs is approximately 1 in 2 to 1 in 3, therefore, approximately 1.5-2.5 million of the ~72 million pet dogs in the USA will develop hemangiosarcoma and ultimately succumb to the disease. Over represented breeds include the Golden Retriever, German Shepherd Dog, Portuguese Water Dog, Bernese Mountain Dog, Flat Coated Retriever, Boxer, and Skye Terrier though any breed is ultimately susceptible. According to the Golden Retriever Health Study published in 2000, the estimated lifetime risk of HSA in this breed is 1 in 5.

 

Not all splenic masses in dogs are HSA, though it is considered the most common splenic tumor. A " double two thirds rule" has been suggested with regards to canine splenic masses and states that ~2/3 of dogs with splenic masses will have a malignant tumor, and ~ 2/3 of those malignancies will be HSA (a 50:50 rule is also suggested). It is important to remember while HSA remains high on the differential list that other differentials need to be considered such as hematoma, hemangioma and other sarcomas. The author has seen first hand very large, cavitary, aggressive appearing splenic lesions that grossly resemble HSA but on histopathology are actually benign lesions (Hemangioma, Hematoma) these lesions are cured with surgical resection and should be considered especially when discussing surgical and therapeutic options with owners.

 

There is increasing support that dysregulation of molecular pathways governing angiogenesis may be important in pathogenesis of this disease. Studies have demonstrated the over expression of angiogenic growth factors and their receptors: Vascular endothelial growth factor ( VEGF), basic fibroblast growth factor (bFGF) and angiopoietin 1 (ANG-1) in HSA cell lines. The over expression of these growth factors and their receptors are good potential targets for future studies with regards to more targeted therapy, unfortunately preclinical data with regards to dogs treated with currently available tyrosine kinase receptor inhibitors that also block some of these pathways have not yielded significant prolongation in disease free intervals or survival times. In addition, there is a growing body of evidence that supports that hemangiosarcoma develops from endothelial cell precursors/ stem cells at the level of the bone marrow and this is a growing field of study with regards to better detection of these cells (early detection) and for creating new targeted non-toxic therapies. Currently there are no effective tests for early diagnosis and most cases present in hemodynamic crisis (hemoabdomen) after the lesion has ruptured necessitating emergency surgery. Options for therapy are limited largely because the disease is generally not diagnosed until late stage (i.e.splenic rupture and most dogs are not painful or experiencing clinical signs).

 

Unfortunately, the standard of care for the management of this disease consisting of surgery and chemotherapy has not resulted in significant improvement in either disease free intervals or survival times in the past 2 decades. In a recent small study published in JVIM, anti-angiogenic (aka metronomic) chemotherapy was evaluated- In this study dogs received splenectomy followed by an antiangiogenic cocktail and were followed for signs of metastasis- this data set was compared to historical controls (dogs whom received adriamcyin therapy or surgery alone). In this study the dogs that received the antiangiogenic protocol experienced survival times similar to that of historical Doxorubicin treated controls, which suggest some utility for this approach to therapy. Anecdotally, I have combined traditional doxorubicin therapy with an antiangiogenic maintenance protocol and in some dogs this appears to be potentially beneficial while in others it appears to have made no difference in long-term control of the disease. Further randomized, prospective clinical trials are indicated to determine if this approach has any merit in management of the disease. Anti-angiogenic therapy is well tolerated, is low cost and does not interfere with the patients' quality of life.

Hounsfield Scale
HU * definition for ABSTRACT on right

Hounsfield scale, named after Sir Godfrey Newbold Hounsfield, is a quantitative scale for describing radiodensity.

 

The Hounsfield unit (HU) scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the radiodensity of distilled water at standard pressure and temperature is defined as zero Hounsfield units (HU), while the radiodensity of air at STP is defined as -1000 HU. It is the definition for CT scanners that are calibrated with reference to water.The standards were chosen as they are universally available references and suited to the key application for which computed axial tomography was developed: imaging the internal anatomy of living creatures based on organized water structures and mostly living in air.

 

The HU of common substances

The Hounsfield scale applies to medical grade CT scans.

 

Substance

                       HU

Air                                         

−1000

Lung

−700

Soft Tissue

−300 to -100

Fat

−84

Water

0

CSF

15

Blood

+30 to +45

Muscle

+40

Bone

+700(cancellous bone)to +3000 (dense bone)

 

A practical application of this is in evaluation of tumors, where, for example, an adrenal tumor with a radiodensity of less than 10 HU is rather fatty in composition and almost certainly a benign adrenal adenoma.

 

CT machines were the first imaging devices for detailed visualization of the internal three-dimensional anatomy of living creatures, initially only as tomographic reconstructions of slice views or sections. Since the early 1990s, with advances in computer technology and scanners using spiral CT technology, internal three-dimensional anatomy is viewable by three-dimensional software reconstructions, from multiple perspectives, on computer monitors.  Bycomparison,conventional Xray images are two-dimensional projections of the true three-dimensional anatomy.

Tumor Node Metastasis (TNM) Staging System

The stage of a cancer is a description (usually numbers I to IV with IV having more progression) of the extent the cancer has spread. The stage often takes into account the size of a tumor, how deeply it has penetrated, whether it has invaded adjacent organs, how many lymph nodes it has metastasized to (if any), and whether it has spread to distant organs. Staging of cancer is the most important predictor of survival, and cancer treatment is primarily determined by staging. Thus, staging does not change with progression of the disease as it is used to assess prognosis. Patients' cancer, however, may be restaged after treatment but the staging established at diagnosis is rarely changed.

Cancer staging can be divided into a clinical stage and a pathologic stage. In the TNM (Tumor, Node, Metastasis) system, clinical stage and pathologic stage are denoted by a small "c" or "p" before the stage (e.g., cT3N1M0 or pT2N0).


  • Clinical stage is based on all of the available information obtained before a surgery to remove the tumor. Thus, it may include information about the tumor obtained by physical examination, radiologic examination, and endoscopy.
  • Pathologic stage adds additional information gained by examination of the tumor microscopically by a pathologist.
Because they use different criteria, clinical stage and pathologic stage often differ. Pathologic staging is usually considered the "better" or "truer" stage because it allows direct examination of the tumor and its spread, contrasted with clinical staging which is limited by the fact that the information is obtained by making indirect observations at a tumor which is still in the body. However, clinical staging and pathologic staging should complement each other. Not every tumor is treated surgically, therefore pathologic staging is not always available. Also, sometimes surgery is preceded by other treatments such as chemotherapy and radiation therapy which shrink the tumor, so the pathologic stage may underestimate the true stage.

Overall stage grouping
Overall Stage Grouping is also referred to as Roman Numeral Staging. This system uses numerals I, II, III, and IV (plus the 0) to describe the progression of cancer.
  • Stage 0 carcinoma in situ.
  • Stage I cancers are localized to one part of the body.
  • Stage II cancers are locally advanced.
  • Stage III cancers are also locally advanced. Whether a cancer is designated as Stage II or Stage III can depend on the specific type of cancer; for example, in Hodgkin's Disease, Stage II indicates affected lymph nodes on only one side of the diaphragm, whereas Stage III indicates affected lymph nodes above and below the diaphragm. The specific criteria for Stages II and III therefore differ according to diagnosis.
  • Stage IV cancers have often metastasized, or spread to other organs or throughout the body.
 
Within the TNM system, a cancer may also be designated as recurrent, meaning that it has appeared again after being in remission or after all visible tumor has been eliminated. Recurrence can either be local, meaning that it appears in the same location as the original, or distant, meaning that it appears in a different part of the body.


In This Issue
The Majority of Splenic Masses Are Splenic Hemangiosarcomas
NEVOG News
Hounsfield Scale
TNM Staging System
CT Corner
Continuing Education Opportunities
Tech Tip
Newsletter Archive
Abstract
CT Corner 

 

See the case study video below to illustrate how we are using CT as a valuable tool in our hospital group: 

 

Paige - Female, American Eskimo Mix, "Spleen Mass"

 

Continuing Education Opportunities

Drs. Henry, Briere and Reese lead CE courses throughout the year for practicing veterinarians on a wide range of topics in veterinary surgery. Register online   

 

May 22, 2012:

Dr. Michelle Fulks, "Pediatric Emergencies: from Birth and Beyond"  

Tech Tip 

Approximately 5 years ago CCVS converted to paper disposable gowns and drapes and BVS recently converted as well. Two reasons for the conversion were improved sterility and the cost analysis. We would like to share our cost analysis and source analysis with you.

 

Name of Product: Smart Gown Fully Impervious (AAMI level 4) surgical gowns Catalog   #89015 size large- 20/case

 

Cost and Vendor: Cardinal Health- $86.42/case ($4.32 each)

 

Reason:

1. Cloth gowns are not impervious to fluids, such that there is rapid strike-through once the gown material gets wet. This can lead to increased infection rates, which can be disastrous, especially when orthopedic implants are in use. Cloth drapes have the same problem with fluids penetration.

 

2. CCVS studied the expense involved in laundering, repackaging, and sterilizing the cloth gowns (and drapes), taking into account the technician time, energy for the laundering and sterilization, and expense for materials (sterilization wrap, laundry detergent, and water). They discovered that it was more cost efficient to purchase disposable gowns, so they transitioned to Cardinal's disposable gowns. An additional gown fee was not created, since they didn't charge separately for the previous cloth gown usage.

 

CCVS decided to stock two types of disposable gowns: the Smart Gown listed above, which is impervious at the highest level of protection (AAMI level 4). These are used for orthopedic procedures and any soft tissue surgery that might result in a lot of fluid that could strike through a lesser AAMI level gown (hemoabdomens, GDV's, splenectomies, and some dystocias). They also stock an AAMI level 3 gown, called Royal Silk, which is used for other soft tissue procedures where a lot of fluid is not anticipated. These are less expensive, and more commonly used in general practices for spays and neuters. The less expensive gowns are used for "dryer" or non-orthopedic procedures in our referral practices. Which is why they opted to stock two types of gowns. .

 

Royal Silk by Cardinal Health- catalog #9518 (size large): 20/case; $56.82/case ($2.84 each).

 

Visit Our Newsletter Archive 
Read our March newsletter article about Using the Caudal Superficial Epigastric Skin Flap for Hind Limb Defects by visiting our newsletter archive!
Abstract

Comparison between malignant and nonmalignant splenic masses in dogs using contrast-enhanced computed tomography Vet Radiol Ultrasound.  

Wendy D Fife1; Valerie F Samii; Wm Tod Drost; John S Mattoon; Stacy Hoshaw-Woodard

 

The ability of computed tomography (CT) to distinguish malignant from nonmalignant splenic masses was evaluated in 21 dogs with 24 masses. CT scans of the abdomen were performed pre- and postintravenous contrast medium administration before splenectomy or euthanasia. Splenic masses were evaluated objectively based on Hounsfield units (HU) and volume. Subjective criteria included location within the spleen (head, body, or tail), margination, homogeneity, and attenuation compared to the remaining splenic parenchyma. Characteristics of malignant and nonmalignant masses were compared. The nonmalignant masses were divided into splenic hematomas and nodular hyperplasia for further analysis. Fourteen (58.3%) of the masses were nonmalignant; 10 (41.7%) were malignant. Malignant splenic masses had significantly lower attenuation values, measured in HU, than nonmalignant splenic masses, on both pre- and postcontrast images (P<0.05). On postcontrast images, there was a significant difference in attenuation characteristics among all three subsets of splenic masses (malignant, hematoma, hyperplasia), with nodular hyperplasia having the highest HU values (90.3), hematomas having intermediate HU values (62.5), and malignant splenic masses having the lowest HU values (40.1). A receiver operator characteristic curve of postcontrast medium HU values revealed 55 as the best threshold value to distinguish malignant from nonmalignant masses, with those less than the threshold value being malignant. Abdominal CT is a useful diagnostic imaging modality for evaluation of focal canine splenic masses, with a significant difference in imaging characteristics between malignant and nonmalignant masses.


2004 Jul-Aug;45(4):289-97.

1Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH 43210, USA