The Transformation of a Nonfunctioning Islet Cell Tumor of the Pancreas into a Proinsulinoma under Conditions of Lung Metastasis

Abstract

We herein report the first case of a nonfunctioning islet cell tumor that transformed into a proinsulinoma during the process of metastasis to the lungs. This phenomenon was confirmed in a 69-year-old woman with an advanced pancreatic islet cell tumor and multiple liver metastases who later developed multiple lung metastases. She underwent pancreatic resection followed by the administration of chemotherapy and survived for seven years. Although the patient initially had hyperglycemia due to diabetes mellitus, she conversely began to manifest hypoglycemic attacks 63 months postoperatively with the concomitant development of multiple lung metastases. An autopsy revealed that only the tumor in the lungs produced proinsulin; no other hormones were detected.

Metastatic Insulinoma Presenting as a Liver Cyst

“…Our case illustrates that the tumor burden of functioning PanNET may not always correlate with the severity of the symptoms. Alternatively, a neuroendocrine tumor may acquire functionality during the disease progression and a nonfunctioning tumor may transition into a functioning tumor [8].…”

Long-Term Efficacy of S-1 Chemotherapy plus Administration of Octreotide for a Patient with Metastatic Neuroendocrine Tumor (Gastrinoma)

“…Hence, we decided to administer chemotherapy with S-1 and octreotide. To the best of our knowledge, several patients with pancreatic NETs who were treated with S-1 have been reported in the Japanese and English literature (Table 1) [6, 7, 8, 9, 10, 11, 12, 13, 14, 15]. S-1 was used as a single agent, as well as in combination therapy.…”

“…S-1 consists of a combination of drugs such as octreotide, gemcitabine, and streptozocin. The anti-growth effect of S-1 containing chemotherapy varies from partial response to progressive disease by case reports [6, 7, 8, 9, 10, 11, 12, 13, 14, 15]. …”

Morphologically ‘invisible’ proinsulin – secreting adenoma detected by Ga‐68 Exendin‐4 (GLP‐1 Receptor) positron emission tomography/CT

“…However, this suggestion should be handled with caution, due to relatively small case numbers. One case has been reported where not the primary tumour of the pancreas itself but only its lung metastases were secreting proinsulin …”

“…One case has been reported where not the primary tumour of the pancreas itself but only its lung metastases were secreting proinsulin. 16 In the presented case, besides aiming to treat the patient's symptoms, we remained determined to find a focus of the secreted proinsulin to detect a potential malignancy in an early stage of disease.…”