INTRODUCTION: The solitary fibrous tumours of the pleura (SFPT) are uncommon and discovered fortuitously or in patients with non-specific respiratory symptoms. When associated with hypoglycaemia it is commonly referred as Doege-Potter syndrome. This syndrome is described in 2–4% of SFPTs. We present two cases of Doege-Potter syndrome with increased production of “big” IGF-II.
CASE PRESENTATION: Case 1. A 68-years-old woman was presented with a large pleural mass and low blood glucosae level (1,4 mmol/L). She had a long history of headache and decreased consciousness with one-year worsening dyspnoea and rihgt-sided chest pain. The chest x-ray (CXR) and CT revealed an enormous opacity occuping almost the entire right hemithorax. After transthoracic fine-needle aspiration, hystological and immunohistochemical analysis diagnosed a benign SFPT. Although surgical resection of such hudge tumour with hypoglycaemia is usually currative, our patient declined surgery and opted for conservative treatment of intravenous glucosa.Case 2. This is a case report of a 55-year-old woman with a large SFTP who was admitted with a loss of consciousness due to hypoglycemia (0.2 mmol/L), transient dysarthria and right-sided hemiparesis. She had 10-year history of dizziness, headaches and impaired concentration, and 12-months history of progressive dyspnea, right-sided chest pain, urinary incontinence, confusion and impaired consciousness. A possibility of a disease of the central nervous system was ruled out by CT and MRI scans. CXR and CT indicated a huge heterogenous mass lesion at the right thoracic cavity. Transthoracic fine-needle aspiration was performed. Based on macroscopic appearance, histological pattern and immunoprofile, the tumor was diagnosed as benign SFTP. Pulmonary function tests demonstrated a moderate restrictive pattern of impaired ventilation. Doppler echocardiography demonstrated moderate pulmonary hypertension. She underwent a standard posterolateral thoracotomy with complete excision of the tumor. There was a large lobulated and pedunculated tumor at the base of pulmonary ligament not adherent to surrounding structures, with subsequent atelectasis of the right middle and lower lobes. Postoperative recovery was complete and uneventful with normal blood glucose levels. Three years after the surgery, there were no symptoms or signs of tumor relapse.
DISCUSSIONS: In 1930, Doege first described the tumor of non-beta cells associated with hypoglycemia, presenting the patient with fibrous tumor of mediastinum. Brusseli et al. in 1981 published the study on eight SFTP patients among whom 4% had hypoglycemia. Giant fibrous tumors cause hypoglycemia by different mechanisms, such as: IGF-II secretion, increased consumption of glucose in so huge tumor, proliferation of insulin receptors in tumor cells, reduced gluconeogenesis and lower effective glucagon secretion. IGF-II secretion is thought to be the most likely mechanism of hypoglycemia origin in patients with SFTP because some solitary fibrous tumors produce excessive quantity of “big” IGF-II because of sudden expression of pro-IGF-II gene in tumor cells. In presented cases, benign SFTPs were diagnosed after fine-needle biopsy, using the histological and immunohistochemical analysis - tumor cells exhibited diffuse cytoplasmic positivity of vimentin, were positive for bcl-2 with no cytonuclear abnormalities. Strong and uniform reactivity of CD34 were manifested in spindle and round cells. The tumors’ cells showed immunoreactivity for IGF-II and E-domain of pro-IGF-II in its Golgi areas. Therefore, we assumed that hypoglycemia has been caused by increased production of “big” IGF-II. In order to examine the other possible causes of hypoglycemia in both patients, we performed the encrinological tests and excluded the most common causes of hypoglycemia (insulinoma, exogenous insulin, adrenal insufficiency, hypopituitarism).
CONCLUSION: The presence of SFPTs with IGF-II secretion possibly producing insulin like neuropeptides, were considered the most likely mechanism of hypoglycemia origin. Clinicians should be aware of this rare, but important cause of hypoglycemia.
DISCLOSURE: Branislava Milenkovic, No Financial Disclosure Information; No Product/Research Disclosure Information