Sertoli Cell Tumor
Dr. Douglas Brum
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.
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.