A 72-year-old man was referred to our hospital for treatment of hypoglycemia and a large pelvic tumor. Magnetic resonance imaging (MRI) revealed a lobulated tumor with iso- and high-intensity areas combined in T2-weighted images.The tumor was resected, and hypoglycemic symptoms disappeared immediately.
A 72-year-old man was admitted to the emergency department for a hypoglycemic attack. The computed tomography (CT) scan detected a large tumor in the pelvic cavity, and he was referred to our hospital for closer examination. The patient had no relevant medical history and was not on any medication. On admission, his blood glucose level was 52 mg/dl (normal range 70–109 mg/dl); serum insulin level, 1.0 μIU/ml (normal range 3–15 μIU/ml); C-peptide level, 0.2 ng/ml (normal range 0.43–2.35 ng/ml), and IGF-I level, 31 ng/ml (normal range 58–198 ng/ml).
Contrast-enhanced CT indicated a heterogeneous spheroid mass with little contrast-enhancement measuring 13 × 9 × 11 cm in the pelvic cavity. CT-angiography revealed the presence of feeding vessels branching from the right and left internal iliac arteries. Magnetic resonance imaging (MRI) revealed a lobulated tumor with iso- and low-intensity areas combined in T1-weighted images, and iso- and high-intensity areas combined in T2-weighted images. No clear invasion to any adjacent organs was identified. Positron emission tomography (PET)-CT revealed heterogeneous accumulation on the tumor with a maximum standardized uptake value (SUVmax) of 2.5.
Hypoglycemia was observed despite continuous glucose infusion, and glucocorticoid administration was initiated prior to tumor resection. The tumor was located retroperitoneally, fed by the superior vesical artery, and was completely excised. Operation time was 388 min, and intraoperative blood loss was 1410 ml.
Macroscopically, the tumor was solid and composed of partially necrotic grayish-white tissue; the tumor measured 15 × 8 × 8 cm and had a fibrous capsule. When observed under the microscope, the tumor was composed of spindle cells arranged in no particular pattern. Seven mitoses were counted per 10 high-power fields (HPF). Immunohistochemical staining revealed that the tumor was positive for signal transducers and activators of transcription 6 (STAT6), CD99, bcl-2, insulin-like growth factor-2 (IGF-II), and CD34, and negative for CD31, EMA, S-100, SMA, and desmin. From these findings, we diagnosed this tumor as an SFT with malignant potential that secreted IGF II, which caused hypoglycemia.
The postoperative course was uneventful, and hypoglycemic symptoms disappeared immediately after surgery. There has been no tumor recurrence during the 1 year of follow-up.