Recurrent Falls Due to Hypoglycemia: Case of an IGF-2-producing Fibrous Tumor of the Pleura

Abstract

This case report delineates the clinical presentation of a 77-year-old male who experienced falls and sustained a humerus fracture attributed to hypoglycemia. Despite the absence of insulin use and normal laboratory results for cortisol, TSH, blood count, and liver and kidney function, a fasting test revealed diminished C-peptide and insulin levels, ruling out insulinoma, exogenous insulin use, or β-cell hyperplasia. Subsequent laboratory investigations demonstrated lowered IGF-1 and elevated IGF-2 levels, indicative of an IGF-2-producing tumor as the etiology of the hypoglycemia. A positron emission tomography computed tomography scan identified a right-sided thoracic cavity tumor, prompting an open resection. Postoperatively, hypoglycemic episodes abated within 2 days, and pathology confirmed a 14.9-cm solitary fibrous tumor. Nonislet cell tumor hypoglycemia (NICTH), also known as Doege Potter syndrome, arises from aberrant production of IGF-2 or its precursors. Elevated IGF-2 levels induce hypoglycemia through heightened glucose uptake on binding to insulin receptors. The literature supports the efficacy of both surgical intervention and corticosteroids in managing NICTH. This case underscores the importance of considering NICTH as a rare etiology in unexplained hypoglycemia cases, advocating for the utility of fasting tests in diagnosis, and suggesting surgical resection as a viable treatment option when radical excision is feasible.

Keywords: IGF-2; NICTH; big IGF-2; hypoglycemia.

Figure 1.

Computed tomography scan. A large solid mass of the right pleura with a diameter of 14 × 14 × 11 cm located above the diaphragm.

Figure 2.

Histology of solitary fibrous tumor. Macroscopy showed a large solid mass of the right pleura with a diameter of 14 × 14 × 11 cm (A). Histology showed a fascicular proliferation of monomorphic, bland spindle cells without prominent mitotic activity and no necrosis (B, C). Tumor cells showed strong nuclear positivity for STAT6 immunohistochemistry confirming the diagnosis of solitary fibrous tumor (D).