P-02 A case of solitary fibrous tumor originating from the adrenal gland presenting with hypoglycemia

Abstract

Introduction

Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm usually located in the pleura and associated with NAB2-STAT6 gene fusion. According to the World Health Organization (WHO) classification, although most SFTs are considered well benign, some SFTs have cytological atypia, hypercellularity, tumor necrosis, Ki-67 greater than 5%, high mitotic rate (>4 per high-power field (HPF)) and/or the presence of infiltrative surgical margins are considered malignant. SFT with severe hypoglycemia is called Doege-Potter syndrome which occurs with ectopic secretion of a prohormone of insulin-like growth factor 2 (IGF-2) from tumor tissue. We present a case who applied with severe hypoglycemia and was diagnosed with a solitary fibrous tumor thought to originate from the adrenal gland located in the right retroperitoneal region.

Clinical Case

A 61-year-old female patient was admitted to the hospital after hypoglycemia was detected in her application due to clouding of consciousness. While the patient's glucose level was 23 mg/dL, insulin:0.4 µIU/mL, C-peptide:<0.01 ng/mL, serum cortisole: 24,20 (µg/mL), growth hormone (GH): 13,20 ng/ mL and insulin-like growth factor I (IGF-1) 38 ng/mL were measured. Insulinoma was excluded and because of IGF-2 level could not be measured in our hospital, low serum insulin and IGF-1 levels suggested high serum IGF-2 levels. HbA1c, adrenal gland, and pituitary function tests were normal (Table 1). A mass lesion of approximately 145×133 mm in size, with heterogeneous contrast, containing cystic areas, was seen, which was thought to originate from the right adrenal gland in the upper abdomen tomography taken due to the presence of a palpable abdominal mass on physical examination (Figure 1). Urine catecholamines were found to be normal, and the plasma aldosterone concentration (PAC)/plasma renin activity (PRA) ratio was 2.56. The patient was operated under intravenous infusion of 10% dextrose due to persistent hypoglycemia. The immunohistochemical evaluation showed CD34, SOX-1 and STAT6 positivity and negativity for S-100, HMB45, straight muscle actin, desmin, caldesmon and melan A, thus confirming the diagnosis of a solitary fibrous tumor. After the operation, the patient's hypoglycemia disappeared. Since there are cases in the literature in which Doege-Potter syndrome was diagnosed without measuring IGF-2, we think that our patient had IGF-2-related hypoglycemia.

Conclusion

The development of hypoglycemia in Doege-Potter syndrome has been associated with the secretion of large amounts of IGF-2 by tumor tissue, resulting in decreased IGF-1 and Insulin-like growth factor-binding protein 3 (IGFBP-3) concentrations. In these patients, the tumor originates from mesenchymal tumors of low malignant potential. In our case, the Ki-67 proliferation index was around 2%, it was considered benign, and the patient's symptoms completely regressed after resection.

Figure 1.

CT images of the patient

A mass in the right retroperitoneal area, associated with the adrenal gland and containing areas of necrosis, is seen on non-contrast (a) and contrast-enhanced (b) CT scans.

 

Table 1.

Laboratory workup