A case of non–islet cell tumor hypoglycemia caused by recurrent renal cell carcinoma as a result of the production of high-molecular-weight insulinlike growth factor–2 was reported online in the Journal of Clinical Oncology.
Malignant fibrous histiocytoma is the most common origin of non–islet cell tumor hypoglycemia (NICTH), while NICTH caused by renal cell carcinoma is rare, Dr. Shingo Kimura of the Tohoku University, Sendai, Japan, and associates reported (J. Clin. Oncology 2014 April [doi:10.1200/JCO.2013.49.5374]).
The 60-year-old male patient had a history of radial nephrectomy for a left renal tumor 17 years earlier, but no recurrence had been observed as of the 10-year postoperative follow-up. Computed tomography found a relatively homogeneous, hypervascular 20-cm tumor in the left retroperitoneal space. It was widely adherent to the stomach, pancreas, and colon.
Once the tumor was removed, hypoglycemia disappeared immediately, and the patient has remained free from hypoglycemia and tumor recurrence for 1 year postoperatively.
Hypoglycemia can be induced by several different tumors, including islet cell and non–islet cell tumors, the researchers noted. The most common cause of NICTH is the overproduction of the proprotein insulinlike growth factor–2 (IGF-2) because of its high molecular weight. The structure and function of IGF-2 are similar to those of insulin, and the protein may interfere with the insulin receptor and lead to hypoglycemia.
In the patient, there were strongly positive indications of IGF-2 in both the primary renal tumor and the retroperitoneal tumor; however, hypoglycemia had not been observed in the primary renal tumor. While NICTH originating from renal cell carcinoma is rare, three cases have been reported. However, this is the first case of recurrent renal cell carcinoma that led to NICTH, the researchers said.
The authors reported no financial conflicts of interest.