Summary

Multiple endocrine neoplasia type 1 (MEN1) requires a high level of suspicion, and late diagnosis can lead to dire outcomes. Genetic counselling is an important part of management, with a lack of evidence surrounding an optimal approach in Aboriginal Australian populations. Our case surrounds a remote-dwelling 48-year-old Aboriginal Australian female who was reviewed by an inpatient endocrine team in 2020 for persistent hypercalcaemia on a background of a parathyroidectomy in 2011 for primary hyperparathyroidism (PHPT), while she was admitted to a local hospital for acute chronic abdominal pain. Relevant medical history included multiple pulmonary embolisms/deep vein thrombosis, myocardial infarction, atrial fibrillation, chronic thromboembolic pulmonary hypertension, right heart failure, human T-lymphotropic virus 1, recurrent abdominal pain, and gastro-oesophageal reflux disorder. Gastroscopies from 2013 and 2015 demonstrated chronic gastritis with hundreds of gastric polyps. Subsequent laboratory studies, neuroendocrine tumour (NET) screening, and CT imaging demonstrated a recurrence of PHPT and a new diagnosis of Zollinger–Ellison syndrome. A 68-gallium-DOTATATE PET/CT was in keeping with metastatic NET. Pituitary studies were normal. Genetic testing confirmed a rare heterozygous variant of c.207dupC in exon 2 of the MEN1 gene. Treatment was symptom based due to terminal comorbidities. Genetic counselling was attempted; however, cultural and logistical barriers were identified and the family declined further testing. Unfortunately, she died in 2021 from multifactorial respiratory failure. This case highlights the need for better approaches to genetic counselling systems for remote Aboriginal Australians and emphasizes the importance of early recognition and the challenges faced in remote areas in making such rare diagnoses.

Learning points

• Remote healthcare systems often lack access to adequate specialist care, resulting in delayed diagnosis of rare conditions and leading to morbidity and mortality.

• Further research and work need to be done to provide culturally appropriate genetic counselling systems in remote Aboriginal Australians.

• A high index of suspicion is required to diagnose MEN1.

• Consider MEN1 in any patient diagnosed with primary hyperparathyroidism, with age <40, and/or with the presence of multiglandular disease or with the presence of Zollinger–Ellison syndrome.

• MEN1 may be under-recognized in Aboriginal Australians.

Summary

Pregnancy in the setting of metastatic paraganglioma is challenging, particularly in the context of tyrosine kinase use. We describe a 26-year-old female with a background of metastatic paraganglioma harboring a pathogenic SDHB variant, requiring sunitinib, which was withheld to facilitate the safe conception and delivery of a healthy baby. She required no alpha- or beta-blockade during her pregnancy and exhibited no signs of tumor progression or symptoms throughout this period. Historically, higher rates of fetal and maternal morbidity and mortality have been experienced in the setting of pregnancy. Although limited data exist on the management of metastatic paraganglioma in pregnant patients, this case suggests that careful treatment modifications, such as temporary tyrosine kinase therapy cessation and vigilant monitoring, can result in successful pregnancies without compromising maternal or fetal well-being.

Learning points

• Paraganglioma in pregnancy has been associated with poor fetal and maternal morbidity and mortality.

• Many of the treatment modalities for metastatic paraganglioma, including tyrosine kinase inhibitors, can affect fertility or cannot be utilized in pregnancy, necessitating the temporary suspension of these treatments.

• This case exemplifies that careful clinical and biochemical monitoring during pregnancy is required to avoid maternal and fetal harm while balancing the risk of disease progression off treatment.

Summary

RET mutations are implicated in 60% of medullary thyroid cancer (MTC) cases. The RET-selective tyrosine kinase inhibitor selpercatinib is associated with unprecedented efficacy compared to previous multi-kinase treatments. Langerhans cell histiocytosis (LCH) is a clonal histiocytic neoplasm usually driven by somatic BRAF mutations, resulting in dysregulated MAPK signalling. We describe a 22-year-old woman with metastatic MTC to regional lymph nodes, lung and liver. Tumour tissue harboured a somatic pathogenic RET variant p.(M918T) and selpercatinib was commenced. She experienced sustained clinical, biochemical and radiological responses. Two years later, she developed rapidly progressive apical lung nodules, prompting biopsy. Histopathology demonstrated LCH with a rare BRAF variant p.(V600_K601>D). The lung nodules improved with inhaled corticosteroids. We hypothesize that selective pressure from RET blockade may have activated a downstream somatic BRAF mutation, resulting in pulmonary LCH. We recommend continued vigilance for neoplasms driven by dysregulated downstream MAPK signalling in patients undergoing selective RET inhibition.

Learning points

• Patients with RET-altered MTC can experience rapid disease improvement and sustained disease stability with selective RET blockade (selpercatinib).

• LCH is a clonal neoplasm driven by MAPK activation, for which the most common mechanism is BRAF mutation.

• Both MTC and pulmonary LCH are driven by dysregulated MAPK signalling pathway activation.

• We hypothesise that the RET-specific inhibitor selpercatinib may have caused the activation of dormant LCH secondary to selective pressure and clonal proliferation.

Summary

Struma ovarii is an ovarian teratoma that comprises 2–5% of all ovarian teratomas. Malignant transformation of struma ovarii occurs in less than 5% of all cases, and metastatic disease is even rarer. We report two cases initially diagnosed with benign struma ovarii that presented malignant transformation, specifically highly differentiated follicular carcinoma of the ovary (HDFCO), some years after the first diagnosis. Case 1 concerns a 37-year-old female featuring HDFCO of the right ovary with multiple metastatic foci, who was diagnosed with benign struma ovarii 14 years ago. Case 2 concerns a 26-year-old female diagnosed with HDFCO of the left ovary. This patient was initially diagnosed with benign struma ovarii 6 years ago that recurred 4 years after the diagnosis. Both patients were treated with surgery, adjunctive total thyroidectomy, and radioactive iodine (¹³¹I) therapy.

Learning points

• Malignant transformation of struma ovarii is very rare (<5%).

• Diagnosis of HDFCO without extra ovarian dissemination is difficult due to the resemblance of its histological appearance with normal thyroid tissue.

• There is no consensus on the postoperative treatment of malignant struma ovarii (MSO). Clinical and histological features of MSO should be assessed for the postoperative treatment decisions.

• TSH suppression and thyroglobulin level measurements are necessary for patient follow-up.

Summary

Functioning gonadotroph tumors are rare neoplasms that can cause ovarian hyperstimulation syndrome (OHSS) in women of reproductive age. Here, we present a case of a follicle-stimulating hormone (FSH)-producing pituitary neuroendocrine tumor (PitNET) with irregular menstrual cycles and OHSS in a Japanese woman. A 34-year-old woman with bilateral multi-cystic ovarian mass was referred to our hospital for ovarian surgery. The imaging feature of magnetic resonance imaging (MRI) of the ovary and elevated estradiol levels with normal FSH and low luteinizing hormone (LH) levels led us to suspect the presence of a functioning gonadotroph PitNET. MRI revealed a 19-mm pituitary tumor, and increased tracer uptake was observed in the pituitary lesion on ¹¹¹In-pentetreotide scintigraphy. Transsphenoidal tumor resection resulted in the resolution of the ovarian enlargement, normalization of her menstrual cycles, and spontaneous pregnancy. Immunohistochemistry (IHC) of the resected tumor for pituitary transcription factors, including steroidogenesis factor 1 (SF1) and estrogen receptor alpha, demonstrated positive immunoreactivity, whereas IHC for pituitary-specific positive transcription factor 1 was negative, suggesting that the tumor belonged to the SF1 lineage of PitNETs (gonadotroph tumor). The tumor cells showed positive expression of FSHβ, while LHβ was mostly negative. Consistent with the high pituitary tumor uptake observed on ¹¹¹In-pentetreotide scintigraphy, the pituitary tumor showed positive expression of somatostatin receptor 2A. Detailed clinical and histological evaluations will provide useful information to understand these rare functioning gonadotroph tumors better.

Learning points

• Functioning gonadotroph tumors are very rare neuroendocrine tumors of pituitary origin.

• Women of reproductive age presenting with bilateral multi-cystic ovarian enlargement, irregular menstrual cycles, and hyperestrogenemia under unsuppressed follicle-stimulating hormone (FSH) levels should be evaluated for FSH-producing tumor.

• Raising awareness of OHSS due to functioning gonadotroph tumors is crucial to prevent unnecessary ovarian surgery.

• Comprehensive histological analysis may provide useful information to better understand the characteristics of functioning gonadotroph tumors.

Summary

Non-islet cell tumour hypoglycemia (NICTH), typically mediated by insulin-like growth factor 2 (IGF-2), is a rare but highly morbid paraneoplastic syndrome associated with tumours of mesenchymal or epithelial origin. Outside of dextrose administration and dietary modification which provide transient relief of hypoglycemia, resection of the underlying tumour is the only known cure for NICTH. Available medical therapies to manage hypoglycemia include glucocorticoids, recombinant growth hormone, and pasireotide. We report two cases of IGF-2 mediated hypoglycemia. The first was managed surgically to good effect, highlighting the importance of a timely diagnosis to maximise the likelihood of a surgical cure. The second patient had unresectable disease and was managed medically, adding to a growing number of cases supporting the efficacy of glucocorticoids and recombinant growth hormone in NICTH.

Learning points

• Recurrent fasting hypoglycemia in the setting of a malignancy should raise suspicion of non-islet cell tumour hypoglycemia (NICTH), which is typically mediated by IGF-2.

• The initial workup for NICTH should include a serum glucose, C-peptide, insulin, insulin antibodies, beta-hydroxybutyrate, IGF-2, IGF-1, and sulphonylurea screen during a spontaneous or induced hypoglycemic episode.

• An IGF-2/IGF-1 ratio above 10 is highly suggestive of IGF-2-mediated hypoglycemia if the IGF-2 level is normal or elevated. False positives may be seen with sepsis and cachexia as both IGF-2 and IGF-1 are subnormal in these cases. A low IGF binding protein 3 (IGFBP3), such as in renal failure, may also result in a falsely normal or low IGF-2/IGF-1 ratio.

• Surgical resection of the associated tumour is curative in most NICTH cases.

• When the tumour is unresectable, moderate-dose glucocorticoids, low-dose glucocorticoids in combination with recombinant growth hormone, and pasireotide are medical therapies with promising results in controlling NICTH.

Summary

Carcinoid heart disease is a rare complication of carcinoid syndrome, resulting in right-sided valvular heart disease and subsequent heart failure due to long-term exposure to vasoactive substances. The management of this condition is complex, often requiring surgical intervention. Current perioperative regimens entail the use of prophylactic somatostatin analogs to prevent carcinoid crisis; however, regimens vary widely among practitioners and evidence supporting their efficacy in this clinical setting is mixed. This case report describes the perioperative management of a 65-year-old man with carcinoid heart disease requiring tricuspid and pulmonary valve replacement surgery. As an adjunct to somatostatin analog therapy, the novel tyrosine hydroxylase inhibitor, telotristat, was initiated preoperatively. This combination resulted in normalization of preoperative urinary 5-HIAA levels. The patient successfully underwent tricuspid and pulmonic valve replacement without evidence of carcinoid crisis. This clinical case is the first published documenting the use of telotristat in the perioperative period in a patient with carcinoid syndrome and carcinoid heart disease and was associated with a good long-term outcome despite the high-risk nature of the case.

Learning points

• Carcinoid crisis is a life-threatening complication of carcinoid syndrome, resulting in hemodynamic instability, bronchospasm, and arrhythmia.

• Cardiac surgical patients with carcinoid syndrome present a unique challenge as they are subject to physiologic conditions and medications which can potentiate intraoperative carcinoid crisis.

• Perioperative management of patients with carcinoid syndrome currently entails the use of prophylactic somatostatin analogs; however, these agents do not prevent carcinoid crisis in all cases.

• Telotristat, a tryptophan hydroxylase inhibitor, shows promise as an adjunctive therapy to somatostatin analogs to reduce the risk of intraoperative carcinoid crisis.

Summary

Unawareness of postprandial hypoglycemia for 5 years was identified in a 66-year-old man at a local clinic. The patient was referred to our hospital because of this first awareness of hypoglycemia (i.e. lightheadedness and impaired consciousness) developing after lunch. In a 75 g oral glucose tolerance test, the plasma glucose concentration was decreased to 32 mg/dL (1.8 mmol/L) at 150 min with relatively high concentrations of insulin (8.1 μU/mL), proinsulin (70.3 pmol/L), and C-peptide (4.63 ng/mL). In a prolonged fasting test, the plasma glucose concentration was decreased to 43 mg/dL (2.4 mmol/L) at 66 h with an insulin concentration of 1.4 μU/mL and a C-peptide concentration of 0.49 ng/mL. Computed tomography showed an 18 mm hyperenhancing tumor in the uncinate process of the pancreas. A selective arterial calcium stimulation test showed an elevated serum insulin concentration in the superior mesenteric artery. The patient was then diagnosed with insulinoma and received pancreaticoduodenectomy. Continuous glucose monitoring (CGM) using the Dexcom G6 system showed unawareness of hypoglycemia mainly during the daytime before surgery. When the sensor glucose value was reduced to 55 mg/dL (3.1 mmol/L), the Dexcom G6 system emitted an urgent low glucose alarm to the patient four times for 10 days. Two months after surgery, an overall increase in daily blood glucose concentrations and resolution of hypoglycemia were shown by CGM. We report a case of insulinoma with unawareness of postprandial hypoglycemia in the patient. The Dexcom G6 system was helpful for assessing preoperative hypoglycemia and for evaluating outcomes of treatment by surgery.

Learning points

• Insulinoma occasionally leads to postprandial hypoglycemia.

• The CGM system is useful for revealing the presence of unnoticed hypoglycemia and for evaluating treatment outcomes after surgical resection.

• The Dexcom G6 system has an urgent low glucose alarm, making it particularly suitable for patients who are unaware of hypoglycemia.

Summary

A 55-year-old patient was admitted to our department for the management of a repetitive alteration of consciousness. Biological investigation results were consistent with endogenous hyperinsulinemic hypoglycemia. Insulinoma was therefore suspected. Abdominal computed tomography and endoscopic ultrasound showed no obvious pancreatic mass.Somatostatin receptor scintigraphy showed abnormal radioactive uptake in both the pancreatic tail and the uncinate process. Contrariwise, abdominal magnetic resonance imaging showed a unique lesion in the pancreas tail. The patient was then proposed for pancreatic surgery. Both intraoperative manual palpation and intraoperative ultrasonography of the pancreas showed a single corporal lesion of 1.5 cm. No lesion was found in the uncinate process. After a left pancreatectomy, the lesion was histopathologically confirmed to be a well-differentiated neuroendocrine tumor. The symptoms of the patient resolved almost immediately following the surgery. The follow-up is one and a half years to date.

Learning points

• The exact preoperative localization of the pancreatic mass remains the most challenging part of insulinoma diagnostic workup.

• The radiologist’s experience is the best warrantor to a precise localization of the tumor.

• ¹¹¹In-DTPA-octreotide uptake in the pancreatic uncinate process may be physiological and its interpretation must, therefore, be vigilant.

• Manual palpation along with intraoperative ultrasonography is considered as the most effective method for the localization of insulinomas during open surgery.

Summary

Large-cell neuroendocrine carcinoma (LCNEC) is a rare neuroendocrine prostatic malignancy. It usually arises after androgen deprivation therapy (ADT), while de novo cases are even more infrequent, with only six cases described. The patient was a 78-year-old man with no history of ADT who presented with cervical lymphadenopathy. Diagnostic approaches included PET/CT, MRI, CT scans, ultrasonography, biopsies, and cytological and immunohistochemical evaluations. Results showed a poorly differentiated carcinoma in the thyroid gland accompanied by cervical lymph node enlargement. Thyroid surgery revealed LCNEC metastasis to the thyroid gland. Additional metastases were identified in both the adrenal glands. Despite appropriate treatment, the patient died of the disease. De novo LCNEC of the prostate is a rare, highly aggressive tumor with a poor prognosis. It is resistant to most therapeutic agents, has a high metastatic potential, and is usually diagnosed at an advanced stage. Further studies are required to characterize this tumor.

Learning points

• De novo LCNECs of the prostate gland can metastasize almost anywhere in the body, including the thyroid and adrenal glands.

• LCNECs of the prostate are usually associated with androgen-depriving therapy, but de novo cases are also notable and should be accounted for.

• Further studies are required to fully understand and treat LCNECs more effectively.