Figure 1: An overview of the patient‘s course of disease
The patient was first diagnosed with an intrathoracic SFT and DPS in 2016. After initial R0 resection, DPS recurred in 2021. Since complete resection was rendered untenable, a debulking surgery took place. In November 2022 hypoglycemic symptoms reemerged.
Initially the patient was admitted to a tertiary hospital in 2016 with recurrent confusion, palpitations, reduced appetite, halitosis, and hypoglycemia. She denied dyspnea, fever, night sweats, and unintentional weight loss. Her medical history and physical examination were unremarkable, except for 30 years of passive nicotine exposure and decreased breath sounds in the left lower thorax.
A CT-scan showed a mass primarily located in the left thorax. Laboratory chemistry revealed low serum levels of insulin, proinsulin, and C-peptide. Histology following percutaneous biopsy confirmed the diagnosis of DPS. Tumor extirpation with lower lobe and partial diaphragm resection were performed successful. Pathological examination confirmed the resection status as R0, with a tumor mass of 11.5 cm x 18 cm x 22 cm, weighing 1300 g. Regular follow-up thoracic CT-scans showed slight pleural effusion, but no further signs of malignancy up to five years after the surgery. The patient experienced no further hypoglycemic episodes at this stage.
In 2021, almost five years after the initial diagnosis, the patient reported dyspnea (NYHA II), recurring episodes of dizziness, lethargy, and hypoglycemic syncopes. Once again clinical examination showed slightly decreased breath sounds on the left thoracic side. CT-scans revealed a corresponding tumor mass infiltrating the mediastinum, pericardium, and diaphragm. Due to the tumor morphology R0 resection was deemed unfeasible by the treating physicians. Debulking surgery at the same external tertiary hospital revealed multiple gelatinous, liquified tumor lesions instead of a solid tumor at this time.
The successful debulking surgery improved the patient’s clinical symptoms, who no longer experienced hypoglycemic episodes. Histological examinations of the resected tumor showed fusiform cells with oval, vesicular, and relatively monomorphic nuclei. The tumor was covered with mesothelium (AE1/3(+)) and was CD34(+), BCL2(+), Vimentin(+), AE1/3(-), CD56(-) with a Ki67 index of 10%. There was no overexpression of p53, one mitosis per high-power field (HPF) and necrosis in more than 10% of the tumor.
In November 2022, only one year after the second surgery, another routine control detected rapid tumor progression, with a substantial increase in tumor size. Without clinical symptoms for the first 9 months after her debulking surgery, the patient then gradually experienced recurring hypoglycemic episodes, with increasing intensity and frequency. She reported up to five hypoglycemic episodes per day, with blood glucose levels dropping down to as low as 30 mg/dl (1.7 mmol/l). Uninterrupted sleeping was no longer possible at this stage. The patient had to wake up at night to consume foods with a high glycemic index in order to artificially maintain blood glucose levels above 50 mg/dl (2.8 mmol/l).
Radiological imaging showed significant tumor progression compared to the preceding six months. A total of 82 intrathoracic lesions were identified. Additionally, atelectasis of the left lower lobe was assessed. [68Ga]DOTATATE/PET-CT revealed variable and focally increased SSTR-expression of the SFT and further lesions in the pericardial fat tissue (Figure 2)