Summary

Familial renal glucosuria (FRG) is a rare renal tubular disorder characterized by increased urinary glucose excretion despite normoglycemia. It is most commonly caused by pathogenic variants in the solute carrier family V member 2 (SLC5A2) gene. This gene encodes the sodium–glucose cotransporter 2, crucial for glucose reabsorption. We report the case of a 44-year-old male referred to the endocrinology outpatient clinic for unexplained glucosuria despite well-controlled diabetes mellitus with metformin and gliclazide therapy. His main complaints were nocturia and an unintentional 5 kg weight loss in 1 year. A 24-h urinary collection revealed overt glucosuria (23.3 g/1.73 m²/24 h), generalized aminoaciduria, and increased uric acid excretion (fractional excretion: 6.4%). Whole-exome sequencing revealed a novel heterozygous c.469-1G>A likely pathogenic variant in the SLC5A2 gene. Specific analysis of the maturity-onset diabetes of the young type (MODY) gene panel showed no pathogenic variants in the hepatocyte nuclear factor-1A (HNF-1A; MODY3) nor in other MODY-associated genes. We assume that the association of glucosuria, aminoaciduria, and increased uric acid excretion can be explained by the combination of diabetes and the likely pathogenic SLC5A2 variant in this patient. In conclusion, we describe a well-controlled diabetic patient with FRG, associated with a novel heterozygous c.469-1G>A likely pathogenic variant in the SLC5A2 gene.

Learning points

• The diagnosis of a renal tubular disorder should be considered in patients with unexplained glucosuria and diabetes mellitus, especially if the latter is well controlled.

• FRG usually presents with glucosuria but may be associated with generalized aminoaciduria and hyperuricosuria.

• Genetic analysis should be considered in patients with young-onset diabetes and glucosuria, particularly with a positive family history.

Summary

Moyamoya syndrome (MMS) refers to a rare cerebrovascular disorder characterized by progressive stenosis of the intracranial internal carotid arteries and their proximal branches, leading to an increased risk of stroke. While prevalent in Asia, this condition is considerably less common in Western countries, including Europe. The association between MMS and Graves’ disease (GD) has been well documented, primarily in Asian and American populations, notably Latin Americans. In this report, we report the first case of GD with MMS in a Caucasian woman from Western Europe. The precise mechanisms underpinning the correlation between these two conditions remain poorly elucidated but are hypothesized to involve hemodynamic alterations, the toxic effects of anti-thyroid-stimulating hormone receptor antibodies, or a shared genetic predisposition. Our clinical case underscores the significance of thyroid disease screening in suspected MMS cases, as the management of thyroid dysfunction may suffice to improve neurological symptoms.

Learning points

• The association between Graves’ disease (GD) and Moyamoya syndrome (MMS) can manifest in a Caucasian European patient.

• Screening for thyroid disease is essential when MMS is suspected, as treating GD might effectively alleviate neurological symptoms.

• The mechanisms linking GD and MMS remain incompletely understood but may involve hemodynamic shifts, the toxic effect of anti-TSH receptor antibodies, or shared genetic factors.

Summary

Bardet–Biedl syndrome (BBS) is a rare, autosomal recessive, multisystem non-motile ciliopathy of progressive onset. It is primarily characterised by rod–cone dystrophy, early-onset obesity and related complications, postaxial polydactyly, renal and genitourinary abnormalities, learning disabilities, and hypogonadism. The diagnosis is based on Beales’ modified diagnostic criteria. We present a case of two monozygotic female twins, 17 years of age at presentation, referred for obesity since childhood. The initial hormonal work-up was negative and no dysmorphic features were noted. They were diagnosed with exogenous obesity. However, after ophthalmologic problems became apparent, rod–cone dystrophy was observed and genetic testing was performed. A mutation in the BBS2 gene led to the diagnosis of BBS, although the full diagnostic criteria were not met. This case not only highlights the need to raise awareness for BBS but also exposes two limitations of the current diagnostic standard. The first limitation is the low sensitivity of the clinical diagnostic model, due to the progressive onset and the high variability of the syndrome. The second limitation is the unclear role of genetic testing. As genetic testing becomes more widely available, genetic diagnosis preceding clinical diagnosis will become more common, leading to a diagnostic conundrum. We propose an update of the diagnostic model. A less strict application in the presence of confirmed genetic mutations should be applied, as this could facilitate earlier diagnosis and intervention. This is important because therapeutic agents are being developed that could have a significant impact on quality of life and prognosis.

Learning points

• Due to the low prevalence, the significant inter-and intrafamilial variation, and the slowly evolving phenotype, monogenic forms of obesity such as Bardet–Biedl syndrome are difficult to diagnose. Despite advances in the understanding of the presentation, pathophysiology and access to accurate genetic characterisation, a substantial number of diagnoses are still made by ophthalmology, as recognition of BBS in other departments of medicine, remains limited.

• Clinical diagnosis of BBS is based on Beales’ modified diagnostic criteria which require the presence of four primary features or three primary features plus two secondary features. This model has its limitations. Due to the progressive onset of clinical symptoms, patients generally do not meet the diagnostic criteria early in life, leading to a delay in diagnosis. In addition, the role of genetic testing remains controversial. However, as it becomes more widely available, genetic diagnosis may precede a full clinical diagnosis.

• BBS has an impact on the quality of life and prognosis of both the patient and the family. Obesity management strategies are an important part of the multidisciplinary approach, as there is no cure available. Setmelanotide has shown promising results in a phase 3 trial, but its effect in clinical practice remains unproven.

Summary

Mitotane is used for treatment of advanced adrenocortical carcinoma. It is administered when the carcinoma is unresectable, metastasized, or at high-risk of recurrence after resection. In addition, mitotane is considered to have direct adrenolytic effects. Because of its narrow therapeutic–toxic range, therapeutic drug monitoring (TDM) is warranted. In 2020, a left-sided adrenal gland tumor was found (5.8 cm) in a 38-year-old man. Considering the size of this lesion and inability to exclude an adrenocortical carcinoma on imaging, a laparoscopic adrenalectomy was performed. Histopathologic examination determined presence of an adrenocortical carcinoma (pT2N0M0 ENSAT stadium II; ki67 10–15%). There was no evidence for residual or metastatic disease but given the high risk of recurrence, adjuvant therapy with mitotane was initiated. During TDM, a sudden and spuriously high level of mitotane was observed but without signs or symptoms of toxicity. After exploration, it was found that this high concentration was completely due to uncontrolled hypertriglyceridemia. After correction thereof, mitotane levels were again in the therapeutic range. This observation underscores the importance of TDM sampling in a fasting state with concurrent control of prevalent or incident dyslipidemia.

Learning points

• TDM of mitotane is advocated to achieve therapeutic levels while avoiding toxicity. For correct TDM, sampling should be done at least 12 h after last intake of mitotane.

• Although sampling in fasting conditions in not explicitly mentioned in the guidelines, fasting state should be considered as elevated serum triglyceride levels might cause spuriously high mitotane levels.

• In patients undergoing treatment with mitotane and presenting with too high or unexplained fluctuating mitotane levels without signs or symptoms of toxicity, hypertriglyceridemia as a possible cause should be investigated.

• If dyslipidemia occurs in patients under mitotane treatment, other causes than mitotane (e.g. alcohol abuse and diabetes) should be considered and appropriate treatment should be initiated.

Summary

Primary hyperparathyroidism most commonly presents with hypercalcaemia. Rarely, parathyroid apoplexy or haemorrhage mimicking a thyroid bleeding cyst is the first presentation of a parathyroid adenoma. A woman presented with a sudden-onset painful ‘goitre’. Ultrasound showed a cystic nodule located posterior to rather than in the right thyroid lobe, suggesting parathyroid adenoma bleeding. Biochemistry showed mild primary hyperparathyroidism. ^99mTc-pertechnetate/sestamibi showed no uptake in the nodule, which was interpreted as a cold thyroid nodule. ¹⁸F-fluorocholine PET/CT showed uptake in the nodule, suggestive of a parathyroid adenoma. Persistent mild primary hyperparathyroidism complicated by nephrolithiasis and osteopenia favoured parathyroidectomy over a wait-and-see approach. The patient was referred for parathyroidectomy along with right thyroid lobectomy. Pathology showed an adenoma, with an eccentrically located cystic structure filled with red blood cells surrounded by a thickened fibrous capsule. In conclusion, cervical pain/haemorrhage with hypercalcaemia points to the diagnosis of parathyroid apoplexy, mimicking a thyroid bleeding cyst. Workup with ultrasound and, if available, ¹⁸F-choline PET/CT allows for timely surgery, minimizing the risk of recurrent and severe bleeding.

Learning points

• A bleeding cyst may be located posterior to rather than in the thyroid, suggesting a parathyroid haemorrhage.

• Neck pain and/or haemorrhage along with primary hyperparathyroidism point to parathyroid apoplexy.

• A two-step presentation has been described, with a first phase of local symptoms to be followed by visible and possibly life-threatening compressing bleeding.

• Therefore, an expedited workup is needed, allowing for timely surgery.

Summary

The Covid-19 vaccination has been rapidly implemented among patients with cancer. We present two cases of patients with endocrine tumours who developed lymphadenopathy following a Covid-19 vaccination. In the case of a patient with multiple endocrine neoplasia (MEN) 1 syndrome, an 18-fluorodeoxyglucose (18FDG)-PET/CT showed positive axillary lymph nodes. Further work-up with fine needle aspiration showed a reactive pattern following a Covid-19 vaccination in the ipsilateral arm shortly before the 18FDG-PET/CT. A second patient, in follow-up for thyroid cancer, developed clinical supraclavicular lymphadenopathy after a Covid-19 vaccination. Follow-up ultrasound proved the lesion to be transient. These cases demonstrate lymphadenopathy in response to a Covid-19 vaccination in two patients susceptible to endocrine tumours and metastatic disease. With growing evidence about the pattern and occurrence of lymphadenopathy after mRNA Covid-19 vaccination, recommendations for scheduling and interpretation of imaging among cancer patients should be implemented to reduce equivocal findings, overdiagnosis, and overtreatment, while maintaining a good standard of care in oncological follow-up.

Learning points

• Reactive lymphadenopathy is very common after an mRNA vaccination against Covid-19 and should be part of the differential diagnosis in patients with endocrine tumours who recently received a Covid-19 mRNA vaccination and present with an ipsilateral lymphadenopathy.

• A good vaccine history is essential in assessing the risk for lymphadenopathy and if possible, screening imaging in patients with endocrine tumours should be postponed at least 6 weeks after the previous vaccination.

• For now, a multidisciplinary care approach is recommended to determine the necessary steps in the diagnostic evaluation of lymphadenopathy in the proximity of a Covid-19 vaccination.

Summary

Complicated Rathke’s cleft cyst (RCC) is a rare occurrence of symptomatic bleeding or growth of a previously asymptomatic (and often undiagnosed) intrasellar cyst derived from remnants of Rathke’s pouch, situated on the midline between the adeno- and neurohypophysis. Symptoms may be identical to those of pituitary apoplexy: acute onset of headache, hypopituitarism, and neurological disturbances. Both syndromes may also exhibit a similar appearance of a large haemorrhagic sellar mass at initial radiological evaluation. We report on two patients who presented with headache and complete hypopituitarism. Based on the initial MRI, they were first diagnosed with pituitary apoplexy but managed conservatively with hormone therapy alone because of the absence of severe visual or neurological threat. Upon follow-up at 4 months, clinical evolution was good in both patients but their pituitary mass had not reduced in size and, after careful radiologic reviewing, was more indicative of a large midline complicated RCC. In conclusion, the diagnosis of complicated RCC is challenging because it can mimic pituitary apoplexy clinically, biologically, and radiologically. Clinicians should distinguish between the two entities using specific radiological signs or evolution of the mass at MRI if the patient does not undergo surgery. To our knowledge, we report conservative management of this rare condition for the first time, though it seems appropriate in the absence of neurological compromise or visual compression. Long-term follow-up is however mandatory.

Learning points

• Complicated Rathke’s cleft cyst can mimic pituitary apoplexy, presenting with sudden onset of headache, hypopituitarism, and visual and neurological compromise in the most severe cases.

• At diagnosis, pituitary MRI may not be able to differentiate between the two entities, showing a large haemorrhagic mass inside the sella, with little or no normal pituitary tissue visible. Patients are often diagnosed with apoplexy at this stage and may undergo pituitary surgery.

• When surgery has not been performed initially in these patients, repeat imaging at 3–6 months is unchanged and does not show the expected involution usually seen after adenoma apoplexy.

• Conservative management with hormonal replacement seems a valid option in the absence of visual or neurological deficits that would require trans-sphenoidal surgery.

Summary

Pituitary carcinoma is a rare type of malignancy and only accounts for 0.1–0.2% of all pituitary tumours. Most pituitary carcinomas are hormonally active and they are mostly represented by corticotroph and lactotroph carcinomas. Corticotroph carcinoma can present as symptomatic Cushing’s disease or can evolve from silent corticotroph adenoma which is not associated with clinical or biochemical evidence of hypercortisolism. We hereby present a case of a bone-metastasized corticotroph pituitary carcinoma masquerading as an ectopic adrenocorticotropic hormone (ACTH) syndrome in a patient with a history of a non-functioning pituitary macro-adenoma. Our patient underwent two transsphenoidal resections of the primary pituitary tumour followed by external beam radiation therapy. Under hydrocortisone substitution therapy she developed ACTH-dependent hypercortisolism without arguments for recurrence on pituitary MRI and without central-to-peripheral ACTH-gradient on inferior petrosal sinus sampling, both suggesting ectopic production. Ultimately, she was diagnosed with an ACTH-secreting vertebral metastasis originating from the primary pituitary tumour. This case report demonstrates the complex pathophysiology of pituitary carcinoma and the long diagnostic work-up. Certain features in pituitary adenoma should raise the suspicion of malignancy.

Learning points

• The diagnosis of pituitary carcinoma can only be made based on documented metastasis, therefore, due to the often long latency period between the detection of the primary tumour and the occurrence of metastasis, the diagnostic work-up most often spans over multiple years.

• Pituitary carcinoma including corticotroph carcinoma is very rare in contrast to pituitary adenoma and only accounts for 0.1–0.2% of all pituitary tumours.

• Histopathology in pituitary adenoma should certainly accomplish the following goals: accurate tumour subtyping and assessment of tumoural proliferative potential.

• Repeated recurrence of pituitary adenoma after surgical resection, a discrepancy between biochemical and radiological findings, resistance to medical and radiation therapy, and silent tumours becoming functional are all hallmarks of pituitary carcinoma.

• Silent corticotroph adenomas are non-functioning pituitary adenomas that arise from T-PIT lineage adenohypophyseal cells and that can express adrenocorticotropic hormone on immunohistochemistry, but are not associated with biochemical or clinical evidence of hypercortisolism. Silent corticotroph adenomas exhibit a more aggressive clinical behaviour than other non-functioning adenomas.

• Treatment options for corticotroph carcinoma include primary tumour resection, radiation therapy, medical therapy, and chemotherapy. Sometimes bilateral adrenalectomy is necessary to achieve sufficient control of the cortisol excess.

Summary

The pandemic caused by severe acute respiratory syndrome coronavirus 2 is of an unprecedented magnitude and has made it challenging to properly treat patients with urgent or rare endocrine disorders. Little is known about the risk of coronavirus disease 2019 (COVID-19) in patients with rare endocrine malignancies, such as pituitary carcinoma. We describe the case of a 43-year-old patient with adrenocorticotrophic hormone-secreting pituitary carcinoma who developed a severe COVID-19 infection. He had stabilized Cushing’s disease after multiple lines of treatment and was currently receiving maintenance immunotherapy with nivolumab (240 mg every 2 weeks) and steroidogenesis inhibition with ketoconazole (800 mg daily). On admission, he was urgently intubated for respiratory exhaustion. Supplementation of corticosteroid requirements consisted of high-dose dexamethasone, in analogy with the RECOVERY trial, followed by the reintroduction of ketoconazole under the coverage of a hydrocortisone stress regimen, which was continued at a dose depending on the current level of stress. He had a prolonged and complicated stay at the intensive care unit but was eventually discharged and able to continue his rehabilitation. The case points out that multiple risk factors for severe COVID-19 are present in patients with Cushing’s syndrome. ‘Block-replacement’ therapy with suppression of endogenous steroidogenesis and supplementation of corticosteroid requirements might be preferred in this patient population.

Learning points

• Comorbidities for severe coronavirus disease 2019 (COVID-19) are frequently present in patients with Cushing’s syndrome.

• ‘Block-replacement’ with suppression of endogenous steroidogenesis and supplementation of corticosteroid requirements might be preferred to reduce the need for biochemical monitoring and avoid adrenal insufficiency.

• The optimal corticosteroid dose/choice for COVID-19 is unclear, especially in patients with endogenous glucocorticoid excess.

• First-line surgery vs initial disease control with steroidogenesis inhibitors for Cushing’s disease should be discussed depending on the current healthcare situation.

Summary

Vitamin D intoxication in children is rare but its incidence is increasing as vitamin D is supplemented more often and in higher doses. Children with cystic fibrosis (CF) are at risk for vitamin D intoxication due to incorrect compounded preparations of liposoluble vitamins. Here, we report a severe vitamin D intoxication in a 4-year-old girl with CF, due to an error in the compounded vitamin A, D, E, and K preparation, presenting clinically with weight loss, constipation, polydipsia, polyuria, and nycturia. The administered compounded preparation contained 10 000-fold the prescribed vitamin D dose. The patient was treated with hyperhydration, loop diuretics, and bisphosphonates. Serum calcium levels normalized after 4 days but serum 25-hydroxyvitamin D levels remained elevated even up to 2 months after treatment.

Learning points

• Vitamin D intoxication should be ruled out when patients with cystic fibrosis (CF) present with acute polyuria, constipation, and weight loss.

• Prompt treatment is necessary to avert life-threatening complications.

• Regularly measuring serum calcium and 25-hydroxyvitamin D concentrations in children with CF receiving vitamin A, D, E, and K supplements is important during their follow-up.