A 62-year-old Mongol woman was referred to our hospital for further evaluation of an intra-abdominal mass seen on an abdominal computed tomography (CT) scan. She had visited her primary care physician for recently aggravated chronic constipation and intermittent abdominal discomfort. These symptoms had persisted for more than 20 years. Whenever these symptoms were exacerbated, she took medications such as painkillers and laxatives prescribed by several private hospitals. She had no other gastrointestinal symptoms, and there was no change in body weight. Additionally, there were no respiratory or cardiovascular symptoms.
Her medical history was significant for the following illnesses. In 1994, she attended hospital for intermittent lower abdominal pain and constipation; on this occasion she was found to have a large retroperitoneal mass on an abdominal CT scan. Additionally, a chest CT scan showed small, well defined nodular lesions in both peripheral lung fields. A sonography-guided fine needle aspiration biopsy of the retroperitoneal mass was performed. The cytological findings revealed an atypical spindle cell tumor, and differential diagnoses of malignant fibrous histiocytoma, leiomyosarcoma, fibrosarcoma and malignant schwannoma were considered. At that time, she was diagnosed with retroperitoneal sarcoma with lung metastases. She received six cycles of ifosfamide (1440 mg/m2 on days one to five) and etoposide (80 mg/m2 on days one to five). After completion of the planned chemotherapy, there were no significant interval changes in the size of the retroperitoneal mass. Additionally, she received six cycles of CYVADIC (cyclophosphamide 500 mg/m2, doxorubicin 50 mg/m2, vincristine 1.5 mg/m2 on day one, dacarbazine 250 mg/m2 on days one to five) chemotherapy. She was then lost to follow-up and had received no further treatment since then.
In November 2005 and January 2007, she visited the Department of Respiratory Medicine at our hospital due to symptoms of upper respiratory infection. She underwent abdominal and chest CT scans on both these visits. Between 2005 and 2007, her CT findings showed no significant change in the size of the retroperitoneal mass and lung metastatic nodules. At eight years before the diagnosis of retroperitoneal sarcoma was established, she had undergone a total hysterectomy for uterine leiomyoma at Korea Cancer Center Hospital, Seoul, Korea. Apart from these incidents, she had no other medical problems and her family history was unremarkable. She had no history of alcohol use or smoking.
On physical examination, her breath sounds were clear and there were no palpable lymph nodes. Her abdomen was soft and obese, and there was no abdominal tenderness on palpation. No abdominal masses were identified on palpation, and there was no organomegaly. Her blood pressure was 140/90 mmHg, hemoglobin concentration was 15.6 g/dL, white blood cell count was 7600 cells/μL, and platelet count was 205,000 cells/μL. Her serum lactate dehydrogenase (LDH) level was mildly increased to 564 U/L. Other laboratory findings were within their normal ranges. Serum levels of tumor markers cancer antigen (CA) 125, CA 19-9, and carcinoembryonic antigen (CEA) were normal. An abdominal CT scan showed multiple large, well defined, highly enhanced masses in the retroperitoneum and pelvic cavity, and there were no significant changes in the sizes of the masses since November 2005 (Figure 1). A chest CT scan showed multiple, tiny to small cavitary and cystic metastatic nodules in both lungs, and there was also no interval change since November 2005 (Figure 1). There was no significant mediastinal or hilar lymphadenopathy. A F-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) scan showed conglomerated bulky masses with inhomogeneous FDG uptake (maximum standard uptake value (SUVmax) of 4.0) in the retroperitoneum and pelvic cavity. We planned to perform a CT-guided percutaneous lung biopsy, but her pulmonary lesions were too small to be biopsied. Therefore, a partial resection of the retroperitoneal mass was performed for the purposes of debulking and establishing a histopathological diagnosis. During surgery, a huge, fixed, hard mass with a smooth surface was found around the abdominal aorta; this mass was hypervascular and fixed. A retroperitoneal mass of size 12.2 × 6.3 × 4.5 cm was removed. On gross examination, the retroperitoneal mass weighed 283g and was a pale brown color with a whitish homogeneous cut surface. Microscopically, the resected mass was characterized by spindle cell proliferation. Immunohistochemical (IHC) staining for pancytokeratin (AE1/AE3), CD117, PDGFR, CD34, actin, desmin, and S-100 protein was performed. IHC staining results were positive for actin and desmin (Figure 2). The mitotic activity was < 1 mitosis event per 50 high-power fields (HPFs) with mild to focally moderate nuclear atypia and there was no evidence of tumor cell necrosis. The final pathological diagnosis was a retroperitoneal STUMP tumor, with a recommendation for careful clinical follow-up. Additional IHC staining for Ki-67, p53, estrogen receptor (ER), and progesterone receptor (PR) was performed. The Ki-67 labeling index was less than 5%, and results were negative for p53. IHC staining results for both ER and PR were positive (Figure 2). We considered angioembolization as treatment for the tumors because of the tumor hypervascularity. Angioembolization was performed with polyvinyl alcohol particles (Boston Scientific, Fremont, California, USA) and multiple microcoils (Tornado, Cook, Bloomington, IN, USA) twice in five months. Both the lumbar arteries, the right internal iliac artery and the left renal capsular artery supplying the tumors were embolized. At one month after the last angioembolization, an abdominal CT scan was performed. There was no significant interval change in the size and extent of the retroperitoneal masses.