Management of Ovarian Dysgerminoma Associated with Pseudo-Meigs Syndrome in a Dog

Dysgerminoma is a type of germ cell tumor which is usually malignant and occurs in the ovary. In general, this type of ovarian tumor is rare in dogs and only occurs between 6-12% of cases found. The signs of it greatly vary depending on the origin of the tumor tissue, the size of tumor, and the presence of development of secondary cancer/ tumor. How to treat malignant ovarian tumors in dogs is currently not welled establish due to the lack of evidence and cases.

 

A 10 year old intact female Chihuahua had first showed signs of progressive abdominal pressure and a cough. Her last estrus was approximately 4 months prior to the symptoms. A physical exam reveal an enlarged abdomen, mild muscle weakness, dyspnea (difficulting breathing), and a crackle sound in the lung. A hematologic study was done on her blood and  found mild leukocytosis, and a decrease is packed cell volume. Her serum chemistry showed hyperglycemia (excess of glucose in her bloodstream). A radiographic examination found pleural effusion, which is when there is an unusual amount of fluid surrounding the lung, in this case the right side, and an abdominal mass with multiple cysts and abdominal fluid.

 

Thoracocentesis (removal of fluid from lungs)  and abdominocentesis (removal of fluid from abdomen) are done to relieve the pressure in the abdomen. The mass had caused the stomach, liver, kidney, small intestine and spleen to dislocate. Distinct pulmonary metastasis was not observed (which is lung cancer) after all examinations the doctors suspected a malignant ovarian or uterine tumor due to the location of tumor.

 

Chemotherapy treatment was given to the dog after owner refused surgical removal. Palliative chemotherapy was started and the dog was described as “well tolerated”. After 6 months, CT scans were done and although the mass increased in size, the pleural and abdominal effusions did not reoccur and again metastasis was not detected. The duration of the chemotherapy was prolonged up to 6 weeks depending on the dog's condition. One year after treatment, the dog was marked as exercise intolerant and having lots of panting.

 

The Chihuahua received the intravenous carboplatin chemotherapy 13 times and lived for 431 days. At the autopsy, hemorrhagic abdominal fluid and an enlarged right ovary was found. The histopathological examination of the ovarian mass showed cords of polygonal cell. These are cells that have large vesicular nuclei and prominent nucleoli with almost no cytoplasm. Infrequent multifocal hemorrhage and necrosis (death of cells in organ) was also observed. The scientists observed and determined a diagnosis of ovarian dysgerminoma.

 

Ovarian tumors associated with pleural effusion and ascites (abdominal swelling) are referred to as Meigs syndrome in humans. However, those are usually benign tumors. Pseudo-meigs syndrome is when it is a malignant tumor, as presented in this case. The cause of this is poorly understood. One theory suggested that pleural effusion in pseudo-Meigs’ syndrome is caused by transfer of ascites through the defect in diaphragm and effusions disappear after removal of tumor. In this case, the mass was not surgically removed but the pleural effusion and ascites spontaneously disappeared after chemotherapy and did not reoccur.

 

Surgical removal is the treatment of choice for most ovarian tumors, but often hard to compare to therapeutic responses, such as chemotherapy, due to lack of research evidence on treatments for such tumors. Previously, doctors had treated a limited number of dogs with a combination of surgery and chemotherapy, but the prognosis was described as poor. However, in this case the dog managed to live for 431 days with only the treatment of chemotherapy.

 

To conclude this study demonstrated that pleural effusions and abdominal swelling associated with a tumor can develop in a dog without metastasis (secondary cancer spot) like pseudo-Meigs syndrome. To their knowledge, this is the first case of ovarian dysgerminoma complicated by pseudo-Meigs syndrome in a dog, specifically in a chihuahua.


 

Summary by: Katherine Handley


Citation

 

Kang MH, Min SH, Choi YK and Park HM, 2017. Management of ovarian dysgerminoma associated with Pseudo-Meigs’s syndrome in a dog. Pak Vet J, 37(1): 111-113.