Non-islet cell tumor hypoglycemia caused by intrathoracic solitary fibrous tumor: a case report

BACKGROUND: Non-islet cell tumor hypoglycemia (NICTH) is defined as a form of hypoglycemia caused by an extrapancreatic tumor. Solitary fibrous tumor (SFT) associated with hypoglycemia is rare. CASE PRESENTATION: A 76-year-old woman, who had frequently experienced hypoglycemic symptoms such as presyncope for the prior 6 months, visited our hospital to undergo detailed examinations. Her fasting glucose level was low at 49 mg/dl. The blood levels of IRI and C-peptide were also low at 0.2 μU/ml and 0.21 ng/ml, respectively. Chest computed tomography revealed a mass measuring 15 cm in the left thoracic cavity. Percutaneous needle biopsy yielded a diagnosis of intrathoracic SFT associated with NICTH. The tumor was removed by video-assisted thoracoscopic surgery. Histological examination showed a tumor composed of simple spindle-shaped cells with an irregular arrangement. Immunohistochemical staining was positive for CD34, bcl-2, and vimentin and negative for alpha SMA and mesothelin. These results confirmed the diagnosis of SFT. Her hypoglycemic symptoms resolved rapidly after surgery. The clinical course has since remained favorable with no signs of recurrence. CONCLUSION: We report a case of non-islet cell tumor hypoglycemia caused by intrathoracic SFT. The high-molecular-weight IGF-II produced by the tumor has been regarded as the cause of NICTH.