Overview of Sertoli Cell Tumor in Dogs
A Sertoli cell tumor is a tumor in the testicles that involves the specific cells called Sertoli cells that can occur in dogs. Sertoli cell tumors are usually slow growing and noninvasive, although 10 to 20 percent may be malignant.
The specific cause of tumor development is unknown, but dogs that are cryptorchid, which means they have a testicle that has not descended into the scrotum, are 10 times more likely to develop a tumor. Cryptorchid testicles are generally intra-abdominal (within the abdomen), but may be under the skin in the inguinal area, or the area of the body where the hind leg meets the body wall.
Breeds at greater risk of cryptorchidism like Weimaraners and Shetland sheepdogs are more likely to develop a Sertoli cell tumor. Boxers are at increased risk of all testicular tumors regardless of cryptorchidism. Dogs are more likely to develop a Sertoli cell tumor with age.
Sertoli cell tumors are the most common tumors that cause a male feminizing syndrome due to changes in sex hormone production. About 25 percent of dogs with this tumor develop the male feminizing syndrome. Sertoli cell tumors can also cause a severe bone marrow disorder (bone marrow hypoplasia).
Most dogs that present with Sertoli cell tumors are not ill, and many are simply found during a routine physical examination.
What to Watch For
Signs of Sertoli Cell Tumor in Dogs may include:
Soft or firm swellings in one or both testicles
A single enlarged testicle or asymmetric testicles
Generalized scrotal enlargement
Infertility in the breeding stud dog
If male feminization is present:
Enlargement of the mammary glands
A symmetrical hair loss
Hyperpigmentation, which causes the skin to darken or turn black
Decreased libido and a pendulous prepuce
Diagnosis of Sertoli Cell Tumor in Dogs
A good physical examination including palpation (feeling) of the testicles
Complete blood count (CBC)
Urinalysis with or without culture and sensitivity
Thoracic (chest) and abdominal radiographs (x-rays)
Abdominal and or scrotal ultrasound
Plasma estrogen levels
Serum inhibin concentrations
Fine needle aspiration
Biopsy and histopathology (microscopic analysis of tissue) of removed testicle or tumor
Treatment of Sertoli Cell Tumor in Dogs
Surgical removal of the involved testes (orchiectomy)
Chemotherapy if the tumor has metastasized
Supportive care if associated disease conditions are present
Home Care and Prevention
Watch the incision daily for any sign of swelling or discharge. The scrotal sack may be slightly swollen postoperatively, but the swelling should slowly resolve within a week or two.
If skin sutures are used, they should be removed in 7 to 10 days. If your dog begins to lick the area excessively, an Elizabethan collar may be required.
Seek veterinary care if your dog has a fever or feels ill postoperatively. If your dog had bone marrow hypoplasia due to a Sertoli cell tumor, close monitoring of blood tests will be required.
An excellent preventive measure is to have your dog neutered (castrated) at an early age.
In-depth Information on Sertoli Cell Tumor in Dogs
Usually Sertoli cell tumors are found as incidental findings on a routine physical exam or an owner may notice a swelling on his dog’s testicle. In most cases, the tumor causes no clinical problems; however, Sertoli cell tumors have the potential to be malignant and may cause other serious disease conditions.
Cryptorchid testicles with Sertoli cell tumors may become large enough to cause abdominal distention and pressure on other abdominal organs. This may cause abdominal discomfort or interference with internal organ function. Sertoli cell tumors may also produce excessive estrogen or decreased androgen production, which are changes in sex hormone concentrations. This increase in estrogen levels may lead to serious secondary conditions.
One such condition is known as a male feminizing syndrome. About 25 percent of Sertoli cell tumors cause this syndrome, but the percentage is even greater if a cryptorchid tumor is involved. The elevated estrogen hormones cause the male dog to take on some female characteristics, as well as display other typical signs.
The clinical signs associated with the feminizing syndrome include:
Enlargement of the mammary glands, possibly with the production of milk
Skin changes that follow a pattern typical of an “endocrine alopecia”: symmetrical hair loss starting in the hindquarters and genitalia
Increased skin pigmentation
A pendulous prepuce
Atrophy of the non-neoplastic testicle
Prostatic enlargement and disease (squamous metaplasia and prostatitis) may additionally be seen due to the changes in hormone levels. A much more severe and potentially life-threatening condition associated with chronic (long standing) elevated estrogen levels and Sertoli cell tumors is estrogen-induced bone marrow hypoplasia.
Elevated levels of estrogen have a toxic effect (estrogen toxicity) on the bone marrow, and bone marrow hypoplasia may develop where the cells in the bone marrow are damaged and cannot function properly. Since the cells in the bone marrow normally produce red blood cell, white blood cells and platelets (cells that help in clotting), decreases in all three cell lines may be seen (pancytopenia). This may lead to anemia (from the decreased red blood cells), infections (from the decreased white blood cells), and bleeding tendencies (from the decreased platelets). Bone marrow hypoplasia is the most serious potential sequelae of Sertoli cell tumors.
Other diseases that have similar clinical symptoms as Sertoli cell tumors include:
Other testicular tumors. Interstitial cell tumors and seminomas are other testicular tumors that cause masses on the testes. Both tumors are usually benign, and require aspiration or biopsy to confirm diagnosis.
Orchitis and epididymitis. Inflammations of the testicle and epididymis, the tube-like structure along side the testicle, are usually caused by a bacterial infection. The condition generally is painful, and dogs tend to feel ill. Affected dogs may also have a fever. If the infection is severe, the swelling in the testicle may begin to spread up the scrotum and into the inguinal area. Epididymitis may sometimes be caused by Brucella infection.
Testicular torsion is a twisting of the testicle where blood supply and or lymphatic drainage is compromised. The testicle is usually symmetrically enlarged and painful. The condition is often associated with testicular neoplasia. Testicular torsions occur with greater frequency in abdominal cryptorchid testes.
A spermatocele also called a sperm granuloma may occur due to a cyst-like dilation of the epididymis. Sperm may become trapped inside the dilation, and an inflammatory response may occur. This response may produce a small swelling in the epididymis. It is a benign condition, but may result in infertility.
An inguinoscrotal hernia occurs when abdominal contents pass into the scrotal sac. Most commonly, it is fatty tissue or a loop of bowel that enters through the inguinal canal. It is not a common condition.
If the tumor is located on a cryptorchid testicle and abdominal distention is present, other causes of abdominal swelling would need to be considered, for example other intra-abdominal masses or fluid accumulation.
If the typical alopecia (hair loss) is present with the feminizing syndrome, causes of endocrine alopecia need to be considered. These include: thyroid, adrenal, and growth hormone disorders as well as other causes of estrogen imbalances including oral estrogen administration.
In-depth Information on Diagnosis
Complete physical examination. All intact male dogs should have their testicles palpated as part of their routine physical exam. Most testicular tumors are found incidentally during the exam, since most dogs do not display any symptoms of illness. On the other hand, dogs with the feminization syndrome have typical physical exam changes that suggest a hormonal cause of the problem.
The complete blood count evaluates the red and white blood cells. The test is especially useful if a Sertoli cell tumor is causing bone marrow hypoplasia. Decreased red cell counts (anemia) and low white cell counts would be expected in this serious condition. The reticulocytes (young, recently released red cells from the bone marrow) might be counted to determine whether the bone marrow was responding to the anemia appropriately by producing new young red cells. The reticulocyte count would be low (non-regenerative) if the anemia was due to estrogen toxicity. The only way to confirm the diagnosis of bone marrow hypoplasia is through a bone marrow aspirate and microscopic evaluation of the cell types.
Just as the red and white cell lines are decreased with bone marrow hypoplasia, the platelets (also produced in the bone marrow), may also be decreased. This test is especially important to run if any excessive bleeding or bruising is noted.
The biochemical profile evaluates for liver or kidney disease, diabetes, and changes in electrolytes. Since most dogs are older if they have a Sertoli cell tumor, if is a valuable screening test for other concurrent diseases. If the tumor is malignant, and has metastasized (spread), elevations in liver enzymes might be noted. Additionally, all animals that are to undergo a surgical procedure should have a biochemical profile done as part of their preoperative blood work.
If the testicular swelling is caused by an infection, a urinalysis (with a culture and sensitivity) might show bacteria and an increased white blood cell count. A urinalysis is also needed to fully assess kidney function.
Thoracic radiographs are useful any time a Sertoli cell tumor is suspected. Since these tumors have malignant potential, chest x-rays are taken to determine if the tumor has spread to the lungs. In older animals it is also a good preoperative screening test to evaluate for evidence of heart disease or other lung conditions. In the cryptorchid dog, abdominal radiographs are taken, as many larger tumors may be easily visualized. Abdominal x-rays are also useful in evaluating the size and shape of other abdominal organs. Occasionally, with metastatic disease, the sublumbar (under the lumbar vertebrae) lymph nodes may be enlarged, and visible radiographically.
An abdominal ultrasound is useful to identify a mass within the abdomen as can be seen with a cryptorchid Sertoli cell tumor. The rest of the abdomen can also be checked for signs of tumor spread and other organ involvement. In non-cryptorchid dogs, generalized scrotal swelling is sometimes present. This may prevent accurate identification of a specific mass. A scrotal ultrasound is an excellent test to determine if a tumor is present in a swollen scrotum.
Plasma estrogen levels may be elevated if a male feminizing syndrome is present, but a normal estrogen level does not prohibit the diagnosis.
Swabs of the prepuce may be examined microscopically. The preputial swabs of animals under the influence of elevated estrogen levels typically have cells that are cornified, which is a specific change in the cell characteristics that occur due to higher estrogen levels.
Inhibin is a specific protein that is produced by the Sertoli cells in the testes. Dogs with Sertoli cell tumors generally have elevated levels of this protein. The test is not typically done since it needs to be sent to a specialized laboratory.
With the aid of ultrasound, an abdominal mass can be aspirated by fine needle. The collected cells are then examined microscopically (cytology). A fine needle aspirate is generally a safe and effective method of tissue evaluation, but may not be diagnostic, since only a small amount of cells are collected. Intra-scrotal testicular masses generally do not require ultrasound for aspiration.
A biopsy provides a better sample as a core of tissue is obtained for histopathology (microscopic examination of tissue). Biopsy usually provides more accurate information since a larger amount of tissue can be evaluated. Biopsy of cryptorchid testicles are done using ultrasound as a guide or at surgery. Many times the biopsy is combined with the full removal of the entire tumor (excisional biopsy). Based on the previous diagnostics, it is not always needed to biopsy a tumor prior to its removal.
In-depth Information on Treatment
The treatment of Sertoli cell tumors depends on the location of the tumor and if there are any associated clinical syndromes. Since the prognosis varies so greatly, from excellent to poor, the treatment of each tumor must be individualized. Many dogs with Sertoli cell tumors feel fine and are asymptomatic. The treatment of these animals usually is fairly direct and carries a good prognosis. However, since there is a higher incidence of malignancy in cryptorchid tumors, they need to be treated more aggressively. Other animals may have acute abdominal pain or a distended abdomen and may require rapid intervention. Dogs that have the male feminization syndrome have a good prognosis, as long as there is no evidence of malignancy or bone marrow disease. Animals that have bone marrow hypoplasia due to estrogen toxicity must be treated very aggressively, but tend to do poorly.
Specific treatment for Sertoli cell tumors include:
Orchiectomy (castration). The treatment of choice for Sertoli cell tumors, either scrotal or cryptorchid is the surgical removal of the affected testicle. Both testes are removed due to the high incidence of tumors involving both testicles. Cryptorchid testicles often require major abdominal surgery, and a more prolonged hospital stay. A complete evaluation of all internal organs should be done at surgery to check for evidence of metastatic disease.
Chemotherapy is an option if the tumor has spread. Some of the drugs that have been used in treatment include: cisplatin, cyclophosphamide, vinblastine and methotrexate. Unfortunately, the prognosis of metastatic Sertoli cell tumor is grave regardless of therapy. Chemotherapy may decrease the tumor volume, and improve an animal’s quality of life for a few months but it is not a cure.
Dogs that have bone marrow hypoplasia may be quite ill and require significant care. Therapy for anemia, infection, and potential bleeding problems needs to be addressed. Intravenous fluids, broad-spectrum antibiotics, and blood or platelet transfusions may be needed to stabilize the patient prior to the surgical removal of the tumor. Bone marrow stimulating factors may also be used in an attempt to speed the recovery of the bone marrow cells, although its efficacy is uncertain. Specifically, erythropoietin is used to stimulate the red blood cell lines and granulocyte colony-stimulating factor (G-CSF) may be used for the white blood cell lines. Multiple blood transfusions may be needed to sustain an animal before the bone marrow recovers. Signs of bone marrow improvement may take 3 to 6 weeks, but not be normal for several months. Unfortunately, most animals with bone marrow involvement do not respond to therapy.
Follow-up Care for Dogs with Sertoli Cell Tumor
Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your pet does not improve rapidly.
Administer all medications as directed. Alert your veterinarian if you are experiencing problems treating your dog.
The incision and scrotum should be checked daily for any signs of swelling or discharge. Routine castration usually does not require antibiotics, but if there is a significant amount of discharge from the incision or swelling, infection may be present and require antibiotic treatment. Occasionally blood may ooze into the scrotum post-operatively causing a scrotal hematoma (blood clot). Scrotal hematomas may become quite large and can be painful, but they usually resolve on their own.
If bone marrow disease was present, a CBC and platelet count should be followed closely looking for improvement in the red and white blood cell counts as well as platelets. Prophylactic antibiotics may need to be given long term, while the white blood cell counts are depressed, in an attempt to decrease the incidence of infection.