Experience of X-linked hypophosphatemic rickets in the Gulf Cooperation Council countries: case series

Summary

X-linked hypophosphatemic rickets (XLH), the most prevalent form of inherited hypophosphatemic rickets, is caused by loss-of-function mutations in the gene encoding phosphate-regulating endopeptidase homolog, X-linked (PHEX). This case series presents 14 cases of XLH from Gulf Cooperation Council (GCC) countries. The patients' medical history, biochemical and radiological investigative findings, as well as treatment responses and side effects from both conventional and burosumab therapy, are described. Cases were aged 2-40 years at diagnosis. There were two male cases and 12 female cases. All cases were treated with conventional therapy which resulted in a lack of improvement in or worsening of the clinical signs and symptoms of rickets or biochemical parameters. Side effects of conventional therapy included nausea, diarrhea, abdominal pain, nephrocalcinosis, and hyperparathyroidism, which affected the patients' quality of life and adherence to treatment. In the 10 patients treated with burosumab, there was a marked improvement in the biochemical markers of rickets, with a mean increase in serum phosphate of +0.56 mmol/L and tubular maximum phosphate reabsorption (TmP) to glomerular filtration rate (GFR) ratio (TmP/GFR) of +0.39 mmol/L at 12 months compared to baseline. Furthermore, a mean decrease in serum alkaline phosphatase (ALP) of -80.80 IU/L and parathyroid hormone (PTH) of -63.61 pmol/L at 12 months compared to baseline was observed in these patients. Additionally, patients treated with burosumab reported reduced pain, muscle weakness, and fatigue as well as the ability to lead more physically active lives with no significant side effects of treatment.

Learning points

Conventional therapy resulted in a suboptimal response, with a lack of improvement of clinical signs and symptoms. Side effects of conventional therapy included nausea, diarrhea, abdominal pain, nephrocalcinosis, and hyperparathyroidism, which affected the patients' quality of life and adherence to treatment. Burosumab demonstrated marked improvements in the biochemical markers of rickets, in addition to reducing pain, muscle weakness, and fatigue. There were no significant side effects associated with burosumab therapy.

Selective peripheral tissue response to high testosterone levels in an infertile woman without virilization signs

Summary

Total testosterone, which is peripherally converted to its biologically active form dihydrotestosterone (DHT), is the first-line hormone investigation in hyperandrogenic states and infertility in premenopausal women. Polycystic ovary syndrome (PCOS), the most common cause of hyperandrogenism and infertility in young women, is often associated with mild elevations of total testosterone. Whereas very high levels of total testosterone (>2-3 SD of normal reference), are most often associated with hyperandrogenic signs, menstrual irregularity, rapid onset of virilization, and demand a prompt investigation. Herein, we report a case of a 32-year-old woman who was referred to the endocrinology outpatient clinic due to secondary amenorrhea and extremely high testosterone levels without any virilization signs. We initially suspected pitfalls in the testosterone laboratory test. Total serum testosterone decreased after a diethyl-ether extraction procedure was done prior to the immunoassay, but testosterone levels were still elevated. An ovarian steroid-cell tumor (SCT) was then revealed, which was thereby resected. Twenty-four hours post surgery, the total testosterone level returned to normal, and a month later menstruation resumed. This case emphasizes that any discrepancy between laboratory tests and the clinical scenario deserves a rigorous evaluation to minimize misinterpretation and errors in diagnosis and therapeutic approach. Additionally, we describe a possible mechanism of disease: a selective peripheral target-tissue response to high testosterone levels that did not cause virilization but did suppress ovulation and menstruation.

Learning points

Total testosterone is the most clinically relevant hormone in investigating hyperandrogenic states and infertility in premenopausal women. Very high total testosterone levels in women (>2-3 SD of normal reference) are most often associated with hyperandrogenic signs, menstrual irregularities, and a rapid onset of virilization. In women with very elevated testosterone levels and the absence of clinical manifestations, laboratory interference should be suspected, and diethyl ether extraction is a useful technique when other methods fail to detect it. Ovarian steroid cell tumors (SCT) encompass a rare subgroup of sex cord-stromal tumors and usually secrete androgen hormones. SCTs are clinically malignant in 25-43% of cases. A selective response of peripheral target tissues to testosterone levels, with clinical manifestations in some tissues and no expression in others, may reflect differences in the conformation of tumor-produced testosterone molecules.

A challenging case of a pituitary macroadenoma and toxic thyroid adenoma with inappropriate TSH secretion

Summary

Thyroid-stimulating hormone-secreting pituitary adenomas (TSHomas) are rare, accounting for less than 1% of all pituitary adenomas. We present a case of hyperthyroidism secondary to a likely TSHoma and coexisting functional thyroid adenoma. Laboratory errors and familial abnormalities in thyroid function tests were ruled out, and a diagnosis of the toxic thyroid adenoma was confirmed on a thyroid uptake scan. However, the triiodothyronine suppression test was contraindicated due to the patient's cardiovascular disease, and the thyrotropin-releasing hormone stimulation test, measurement of glycoprotein hormone alpha-subunit, and genetic testing were unavailable. Magnetic resonance imaging of the brain revealed a suprasellar pituitary macroadenoma measuring 40 mm × 20.3 mm × 17 mm. The patient was initiated on carbimazole; however, thyroid stimulating hormone and thyroxine levels remained elevated. The patient declined trans-sphenoidal surgery and was treated with radioactive iodine to manage the toxic thyroid adenoma, leading to reduced thyroxine levels and symptom improvement. Unfortunately, the patient passed away before long-acting somatostatin analogs became available. This case highlights the diagnostic and therapeutic challenges involved in managing thyrotoxicosis with dual etiology.

Learning points

Hyperthyroidism can have multiple etiologies, which can coexist in the same patient. Persistent discordant thyroid function tests warrant further investigation. The gold standard for diagnosis of TSHomas remains immunohistochemical analysis of the tumor tissue.

Two rare cases of benign struma ovarii with malignant recurrence

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.

A rare diagnosis of Langerhans cell histiocytosis made on thyroid histology with coexisting papillary thyroid cancer and AVP deficiency

Summary

A 48-year-old Asian male, presented to the hospital for an elective total thyroidectomy in the context of 6.3 cm thyroid nodule. The fine needle aspiration cytology of the nodule confirmed papillary thyroid cancer (PTC) with some atypical histiocytes. He has a history of idiopathic arginine vasopressin deficiency (AVP-D) and has been taking oral DDAVP 100 µg daily, self-adjusting the dose based on thirst and polyuria. Additionally, he also has a history of recurrent spontaneous pneumothorax. His total thyroidectomy was aborted due to significant intraoperative bleeding, and his admission was further complicated by post-operative hyponatraemic seizure. Thyroid histology revealed the diagnosis of Langerhans cell histiocytosis (LCH), and further investigation with contrast CT demonstrated multi-organ involvement of the thyroid, lungs, and bones.

Learning points

Langerhans cell histiocytosis (LCH) is a condition that can affect one or more organ systems, including the pituitary, where it can present as AVP deficiency. Strict monitoring of fluid balance, as well as serial monitoring of serum sodium, is essential in all patients with AVP-D in the perioperative setting. Iatrogenic hyponatraemic seizure is an uncommon but serious complication of DDAVP treatment in hospitalised patients with AVP-D. DDAVP dosing must be carefully monitored. LCH with multisystem involvement is an important mimic for metastatic conditions, and histological diagnosis is essential to guide treatment and prognosis. Although LCH without bone marrow involvement is unlikely to increase the risk of bleeding, its effect on tissue integrity may make surgery more challenging. BRAF-V600E mutation is an important driver mutation and a potential therapeutic target in the treatment of LCH.

Imatinib use in the management of a patient with Doege-Potter syndrome

Summary

Doege-Potter syndromeis a paraneoplastic syndrome characterized by nonislet cell tumor hypoglycemia due to a solitary fibrous tumor, which produces insulin-like growth factor II. In this report, we present the case of a 67-year-old male with recurrent and refractory hypoglycemia due to DPS successfully treated with imatinib. He initially presented with neuroglycopenic symptoms and dyspnea secondary to a giant tumor in the left hemithorax, which was totally resected. During follow-up, 7 years later, he presented with thoracoabdominal tumor recurrence associated with severe hypoglycemia and underwent subtotal tumor resection, with a subsequent improvement of symptoms. The following year, he had a recurrence of his intra-abdominal tumor, which was unresectable, associated with severe hypoglycemia refractory to dextrose infusion and corticosteroids, thus receiving imatinib with a favorable response. The clinical presentation, diagnostic approach, progression of the disease, and response to treatment with imatinib in the management of a patient with large, recurrent, and unresectable mesenchymal tumors with insulin-like growth factor-2 secretion causing hypoglycemiahighlight the importance of this case report.

Learning points

Doege-Potter syndrome (DPS) is a rare cause of tumoral hypoglycemia of non-pancreatic origin. Some malignant or benignant neoplasms have ectopic secretion of insulin-like growth factor-2. Total surgical removal is the principal treatment in patients with DPS. Tyrosine kinase inhibitors management in DPS may contribute to improved tumor control in patients with unresectable tumors and severe hypoglycemia.

Subacute thyroiditis presenting as a painful suspicious thyroid nodule

Summary

We report a case of subacute thyroiditis in a 40-year-old female who initially presented with painful thyroid nodules without clinical and biochemical evidence of hyperthyroidism. Thyroid ultrasound was done to evaluate the thyroid nodules and fine-needle aspiration (FNA) was performed in view of the suspicious features. As the FNA showed a follicular lesion of undetermined significance or atypia of undetermined significance (FLUS/AUS, Bethesda III), she was advised for surgical excision. She was subsequently diagnosed with subacute thyroiditis based on her clinical symptoms, biochemical evidence of hyperthyroidism, raised erythrocyte sedimentation rate (ESR) as well as low uptake on thyroid scintigraphy. The thyroid lesions disappeared after symptomatic treatment. It is important to recognise that subacute thyroiditis can present with painful thyroid lesions with ultrasound features similar to suspicious thyroid nodules which can resolve with the resolution of the thyroiditis.

Learning points

Subacute thyroiditis can present with atypical features such as the absence of pain, normal erythrocyte sedimentation rate or absence of hyperthyroidism. In subacute thyroiditis, ultrasound findings are commonly described as focal or multifocal lesions with poorly defined and heterogeneous and hypoechoic echogenicity which can be misdiagnosed as malignancy. Thyroid lesions can resolve with the resolution of thyroiditis with or without symptomatic treatment.

Identification of a novel hepatocyte nuclear factor-1 alpha (HNF1A) variant in maturity onset diabetes of the young type 3 (HNF1A-MODY)

Summary

We identified an adolescent young woman with new-onset diabetes. Due to suspicious family history, she underwent genetic testing for common monogenic diabetes (MODY) genes. We discovered that she and her father carry a novel variant of uncertain significance in the HNF1A gene. She was successfully transitioned from insulin to a sulfonylurea with excellent glycemic control. Based on her family history and successful response to sulfonylurea, we propose that this is a novel pathogenic variant in HNF1A. This case highlights the utility of genetic testing for MODY, which has the potential to help affected patients control their diabetes without insulin.

Learning points

HNF1A mutations are a common cause of monogenic diabetes in patients presenting with early-onset diabetes and significant family history. Genetic testing in suspected patients allows for the identification of mutations causing monogenic diabetes. First-degree relatives of the affected individual should be considered for genetic testing. The use of sulfonylurea agents in patients with HNF1A-MODY can reduce dependence on insulin therapy and provide successful glycemic control.

Initial treatment of myxedema coma using oral levothyroxine: a case report from Tanzania

Summary

Myxedema coma is a severe complication of hypothyroidism, commonly affecting women over 60 years of age, causing slow, progressive multi-organ dysfunction, and mental deterioration. Due to improved diagnostics and treatment of hypothyroidism, myxedema coma has become uncommon. However, it is hardly reported in resource-limited settings. We present an elderly female with a history of total thyroidectomy due to multi-nodular goiter. She presented with features of heart failure, excessive weight gain, and cold sensation. Although the patient was on levothyroxine replacement therapy, her laboratory tests were suggestive of overt primary hypothyroidism. During the course of her hospitalization, she developed subcutaneous bleeding with frank hematuria. This led to an altered mental state and hypotension that were suggestive of myxedema coma. Stroke and pulmonary embolism were ruled out as potential differential diagnoses of her current state. She was treated with a high dose of oral levothyroxine followed by 150 μg of oral levothyroxine daily, which resulted in a favorable outcome despite being a fatal emergency. She was also treated with intravenous hydrocortisone and furosemide. Oral thyroid hormone replacement may be an effective option in those resource-limited settings where intravenous thyroid hormone replacement is not available. However, early diagnosis and treatment with an adequate dose of thyroid hormones are crucial to achieve a favorable outcome.

Learning points

Myxedema coma is an uncommon complication of hypothyroidism with a fatal outcome. The diagnosis of myxedema coma is based on clinical suspicion, especially in patients with hypothyroidism and in the presence of precipitating factors. Although diagnostic and scoring criteria based on clinical, laboratory, and imaging features have been proposed, no consensus has been reached. This article shows an alternative treatment option for myxedema coma using oral levothyroxine, which led to a favorable outcome.

Graves' disease in an adolescent presenting with increased intracranial pressure and bilateral papilledema

Summary

Increased intracranial pressure (ICP) can present with symptoms of headache, vomiting, visual changes, and tinnitus. Papilledema may be seen on physical exam. Thyroid disease has been a rare secondary cause of increased ICP. We present a 16-year-old female who had a worsening headache for 6 months. She was found to have signs, symptoms, physical exam findings, and diagnostic studies consistent with both increased ICP and previously undiagnosed Graves' disease. The patient was treated with a 19-month course of methimazole 40 mg daily. Her headache and papilledema resolved shortly after medication initiation. The timeline of symptoms and resolution of her increased ICP symptoms with treatment of Graves' disease suggests that hyperthyroidism was the underlying cause of her increased ICP. Clinicians should consider Graves' disease as the etiology in pediatric patients presenting with signs and symptoms of increased ICP with papilledema.

Learning points

Symptoms of increased intracranial pressure (ICP) include headache, vomiting, transient visual changes, and tinnitus. Secondary causes of increased ICP should be considered in males, young children, older patients, and those not overweight. Clinicians should consider Graves' disease as the etiology in pediatric patients presenting with signs and symptoms of increased ICP with papilledema. They should assess for orbitopathy and thyromegaly and inquire about symptoms that would be indicative of hyperthyroidism.

Posterior reversible encephalopathy syndrome in a patient with a metastatic pancreatic neuroendocrine tumour and ectopic Cushing's syndrome

SUMMARY

We report a rare case of posterior reversible encephalopathy syndrome (PRES), precipitated by ectopic Cushing's syndrome, in a patient with a metastatic pancreatic neuroendocrine tumour. A 55-year-old female presented as a hypertensive emergency with seizures and severe biochemical disturbance, including alkalosis, hypokalaemia and hyperglycaemia. MRI showed vasogenic oedema in the parieto-occipital region, consistent with a diagnosis of PRES. She had a significantly raised serum cortisol (>6000 nmol/L) which did not suppress with dexamethasone. Plasma adrenocorticotropic hormone (ACTH) concentrations were neither suppressed nor raised but were consistently within the normal reference range. The unexpected finding of a normal ACTH may be explained by either tumour secretion of unmeasured ACTH-related peptides, immunoassay antibody interference or episodic ACTH secretion. PRES is usually reversible with prompt and appropriate treatment. Hypercortisolism associated PRES is rare and may be associated with a worse outcome.

LEARNING POINTS

PRES secondary to ectopic Cushing's syndrome is very rare. PRES in this context may indicate a worse prognosis. In ectopic Cushing's syndrome, if the serum ACTH level is normal, consider testing for ACTH-related peptides or interfering antibodies. Further research is required to establish the best treatment approach and to improve patients' outcomes.

Atypical progeroid syndrome (p.E262K LMNA mutation): a rare cause of short stature and osteoporosis

SUMMARY

Lamin A/C (LMNA) gene mutations cause a heterogeneous group of progeroid disorders, including Hutchinson-Gilford progeria syndrome, mandibuloacral dysplasia, atypical progeroid syndrome (APS) and generalized lipodystrophy-associated progeroid syndrome (GLPS). All of those syndromes are associated with some progeroid features, lipodystrophy and metabolic complications but vary differently depending on a particular mutation and even patients carrying the same gene variant are known to have clinical heterogeneity. We report a new 30-year-old female patient from Russia with an APS and generalized lipodystrophy (GL) due to the heterozygous de novo LMNA p.E262K mutation and compare her clinical and metabolic features to those of other described patients with APS. Despite many health issues, short stature, skeletal problems, GL and late diagnosis of APS, our patient seems to be relatively metabolically healthy for her age when compared to previously described patients with APS.

LEARNING POINTS

Atypical progeroid syndromes (APS) are rare and heterogenic with different age of onset and degree of metabolic disorders, which makes this diagnosis very challenging for clinicians and may be missed until the adulthood. The clinical picture of the APS depends on a particular mutation in the LMNA gene, but may vary even between the patients with the same mutation. The APS due to a heterozygous LMNA p.E262K mutation, which we report in this patient, seems to have association with the generalized lipodystrophy, short stature and osteoporosis, but otherwise, it seems to cause relatively mild metabolic complications by the age of 30. The patients with APS and lipodystrophy syndromes require a personalized and multidisciplinary approach, and so they should be referred to highly specialized reference-centres for diagnostics and treatment as early as possible. Because of the high heterogeneity of such a rare disease as APS, every patient's description is noteworthy for a better understanding of this challenging syndrome, including the analysis of genotype-phenotype correlations.

A rare case of ectopic ACTH syndrome caused by primary renal neuroendocrine tumor

SUMMARY

Ectopic adrenocorticotropic hormone (ACTH) secretion is responsible for 5-15% of Cushing's syndrome (CS). Neuroendocrine tumor (NET) is a common cause of ectopic ACTH syndrome (EAS). However, primary renal NET is exceedingly rare. Fewer than 100 cases have been reported and only a few cases presented with CS. Because of its rarity and lack of long-term follow-up data, clinical manifestations, biological behavior and prognosis are not well understood. Here, we report the case of a 51-year-old man who presented with clinical and laboratory findings compatible with EAS. CT scan revealed a lesion of uncertain nature at the lower pole of the left kidney. Octreotide scan found a filling defect at the lower pole of left kidney. It was difficult to determine if this finding was the true etiology or an incidental finding. Unfortunately, the patient's clinical status rapidly deteriorated with limited medical treatment. The patient underwent left nephrectomy and left adrenalectomy. Histopathological examination confirmed NET with oncocytic features. Immunohistochemistry staining was positive for ACTH. The patient's condition gradually improved. Additionally, glucocorticoid replacement was required only 6 months during a gradual recovery of hypothalamic pituitary adrenal axis achieved approximately three years after tumor removal. Although extremely rare, primary renal NET should be considered as a cause of EAS particularly in a patient with rapid clinical deterioration. Thorough investigation, early diagnosis and careful management are crucial to reduce morbidity and mortality.

LEARNING POINTS

Primary renal NET is an extremely rare cause of ectopic ACTH syndrome. Ectopic ACTH syndrome has a rapid onset with severe clinical manifestations. In this case, the patient's condition deteriorated rapidly, resulting from severe hypercortisolism. Resection of the tumor is the most effective treatment. Localization of ectopic ACTH-secreting tumors is very challenging. Multimodality imaging including CT, MRI, octreotide scan, and positron emission tomography plays a crucial role in identifying the tumors. However, each imaging modality has limitations.

Successful long-term use of pioglitazone in Berardinelli-Seip lipodystrophy-associated diabetes

SUMMARY

Berardinelli-Seip congenital lipodystrophy (BSCL) is a rare autosomal recessive disease, characterized by the absence of subcutaneous adipose tissue, leptin deficiency and severe metabolic complications, such as insulin resistance, diabetes mellitus, and dyslipidemia. The most common mutation occurs in BCSL2 which encodes seipin, a protein involved in adipogenesis. We report a patient with BSCL who was diagnosed with diabetes at 11 years old. He was started on metformin 1000 mg twice daily, which lowered glycated hemoglobin (HbA1c) to less than 7%. Four months later, HbA1c raised above 7.5%, indicating secondary failure to metformin. Therefore, we added the peroxisome proliferator-activated receptor-gamma (PPARG) agonist, pioglitazone. Since then and for the last 5 years his HbA1c has been within the normal range. These findings indicate that pioglitazone should be considered as a valid alternative in the treatment of diabetes in BSCL patients. To the best of our knowledge, this is the first specific report of successful long-term treatment with pioglitazone in a patient with BSCL.

LEARNING POINTS

Berardinelli-Seip congenital lipodystrophy (BSCL) is a recessive genetic disorder associated with severe insulin resistance and early onset diabetes, usually around puberty. Failure of oral antidiabetic medication occurs within the first years of treatment in BSCL patients. When failure to achieve metabolic control with metformin occurs, pioglitazone may be a safe option, lowering insulin resistance and improving both the metabolic control and lipodystrophic phenotype. Herein we show that pioglitazone can be a safe and efficient alternative in the long-term treatment of BSCL patients with diabetes.

Recurrent primary hyperparathyroidism: a diagnostic and management dilemma

SUMMARY

Primary hyperparathyroidism requires a surgical approach to achieve a long-term cure. However, post-surgical recurrence significantly complicates the management of this condition. A number of causes for recurrent disease are well understood and several diagnostic modalities exist to localise the culprit parathyroid adenoma although none of them is efficacious in localisation of the recurrent lesion. In this case report, we highlight a novel causative mechanism and describe a unique diagnostic sequence that enabled curative treatment to be delivered.

LEARNING POINTS

In the case described herein, we describe a novel location for a parathyroid adenoma causing recurrent PHPT. The case elucidates well the difficulties presented by such cases in terms of surgical planning and show the utility of PVS in such cases. Based on this case, we make the following recommendations: Meticulous care must be taken to prevent seeding of adenomatous tissue during primary excision. To consider the use of PVS in patients with discordant imaging in the setting of recurrent/persistent PHPT as a method to localise the causative adenoma. Same day PVS and surgery is a viable option for patients who either represent an anaesthetic risk or who are extremely anxious about the prospect of two separate procedures. Disordered calcium homeostasis is an important but forgotten cause of dysphagia which can be extremely debilitating for affected patients.

An infant with congenital nephrogenic diabetes insipidus presenting with hypercalcemia and hyperphosphatemia

SUMMARY

We report a male infant with congenital nephrogenic diabetes insipidus (NDI) who presented with hypercalcemia and hyperphosphatemia since birth. Serum sodium started to increase at 39 days. Although there was no polyuria, urine osmolality was 71 mOsm/kg, when serum osmolality was 296 mOsm/kg with plasma arginine vasopressin 22.5 pg/mL. He was thus diagnosed as NDI. An undetectable level of urine calcium and unsuppressed intact parathyroid hormone suggested hyperparathyroidism including calcium-sensing receptor mutations that could cause hypercalcemia-induced NDI. Polyuria became apparent after the initiation of i.v. infusion for the treatment of hypernatremia. Low calcium and low sodium formula with hypotonic fluid infusion did not correct hypernatremia, hypercalcemia, or hyperphosphatemia. Hydrochlorothiazide and subsequently added celecoxib effectively decreased urine output and corrected electrolytes abnormalities. Normal serum electrolytes were maintained after the discontinuation of low calcium formula. The genetic analysis revealed a large deletion of the arginine vasopressin receptor-2 (AVPR2) gene but no pathogenic variant in the calcium-sensing receptor (CASR) gene. Whether hypercalcemia and hyperphosphatemia were caused by dehydration alone or in combination with other mechanisms remains to be clarified.

LEARNING POINTS

Congenital NDI can present with neonatal hypercalcemia and hyperphosphatemia. Hypercalcemia and hyperphosphatemia can be treated with low calcium and low sodium formula, hydration, hydrochlorothiazide, and celecoxib. Genetic testing is sometimes necessary in the differentiating diagnosis of hypercalcemia associated with NDI.

A novel SOX10 nonsense mutation in a patient with Kallmann syndrome and Waardenburg syndrome

SUMMARY

The underlying genetic drivers of Kallmann syndrome, a rare genetic disorder characterized by anosmia and hypogonadotropic hypogonadism due to impairment in the development of olfactory axons and in the migration of gonadotropin-releasing hormone (GNRH)-producing neurons during embryonic development, remain largely unknown. SOX10, a key transcription factor involved in the development of neural crest cells and established as one of the causative genes of Waardenburg syndrome, has been shown to be a causative gene of Kallmann syndrome. A 17-year-old male patient, who was diagnosed with Waardenburg syndrome on the basis of a hearing impairment and hypopigmented iris at childhood, was referred to our department because of anosmia and delayed puberty. As clinical examination revealed an aplastic olfactory bulb and hypogonadotropic hypogonadism, we diagnosed him as having Kallmann syndrome. Incidentally, we elucidated that he also presented with subclinical hypothyroidism without evidence of autoimmune thyroiditis. Direct sequence analysis detected a nonsense SOX10 mutation (c.373C>T, p.Glu125X) in this patient. Since this nonsense mutation has never been published as a germline variant, the SOX10 substitution is a novel mutation that results in Kallmann syndrome and Waardenburg syndrome. This case substantiates the significance of SOX10 as a genetic cause of Kallmann syndrome and Waardenburg syndrome, which possibly share a common pathway in the development of neural crest cells.

LEARNING POINTS

Kallmann syndrome and Waardenburg syndrome possibly share a common pathway during neural crest cell development. SOX10, a key transcription factor involved in the development of neural crest cells, is a common causative gene of Kallmann syndrome and Waardenburg syndrome. Careful evaluation about various phenotypic features may reveal the unknown genetic drivers of Kallmann syndrome.

Rare presentation of collapse and cardiomyopathy in phaeochromocytoma

SUMMARY

A phaeochromocytoma is a rare neuroendocrine tumour derived from the chromaffin cells of the adrenal medulla. Tumours can produce excessive amounts of catecholamines. The presenting symptoms can vary but often include the classic triad of episodic headaches, sweating and palpitations. Due to catecholamine excess, patients can develop cardiomyopathy. Bradycardia and collapse could be the result of sinus node dysfunction or transient dysregulation of the autonomic nervous system. Patients with co-existing diabetes can have improvement or resolution of their diabetes after successful adrenalectomy. We report a case of an 87-year-old lady who initially presented with sweating, palpitations and collapse, resulting in a permanent pacemaker insertion. She was later found to have a large adrenal incidentaloma with subsequent markedly elevated plasma metanephrine levels. She later presented with chest pain and in acute pulmonary oedema with normal coronary arteries visualised on coronary angiogram. After surgical excision of her phaeochromocytoma, her diabetes resolved with her HbA1c improving from 68 to 46 mmol/mol, with no further requirement for diabetic medications. Her pulmonary oedema improved with no ongoing need for diuretic therapy. This case highlights that phaeochromocytomas can affect multiple systems and there should be a very high index of suspicion in patients presenting with sweating, palpitations, hypertension and a history of diabetes and even in those with collapse.

LEARNING POINTS

There should be a high index of suspicion for phaeochromocytomas in patients with palpitations, diaphoresis, anxiety, hypertension and diabetes. Rarely phaeochromocytomas can present as bradycardia and collapse due to sinus node dysfunction or transient autonomic dysregulation and that should be considered in older patients. Catecholamine cardiomyopathy can occur in phaeochromocytoma with potential resolution after successful surgical excision. Diabetes can resolve after successful surgical treatment of a phaeochromocytoma.

Gynecomastia as a presenting symptom of Graves' disease in a 49-year-old man

SUMMARY

Gynecomastia is a symptom with a potential high disease burden. It has a variety of underlying causes, such as malignant, drug-related or hormonal. The presence of gynecomastia can be explained in thyrotoxicosis due to a concomitant disbalance of sex hormones. Interestingly, it rarely is the presenting symptom of Graves' disease. A 49-year-old man presented to our outpatient clinic with right-sided gynecomastia. After thorough history taking, more symptoms of thyrotoxicosis were present. Treatment was started with thiamazole and later levothyroxine. Three months after this treatment the gynecomastia and other symptoms resolved completely. A disbalance of sex hormones due to an increased expression of the protein sex hormone-binding globulin (SHBG) caused by thyrotoxicosis could result in gynecomastia. In vitro and in vivo research in mice suggest that the pathophysiology of thyrotoxicosis-associated gynecomastia is due to upregulation of hepatocyte nuclear factor-4α (HNF4A) in liver cells. Subsequent increase of SHBG results in a decrease of free testosterone levels.

LEARNING POINTS

Gynecomastia is a common finding (up to almost 40%) on physical examination in patients with hyperthyroidism. In gynecomastia, thyroid function tests should be examined on initial presentation because of the relative simple treatment. The pathophysiology of thyrotoxicosis-associated gynecomastia is well understood by a sex-hormonal disbalance due to an increased expression of SHBG. Due to the well explainable pathophysiology, reduction of symptoms can be expected after treatment. The underlying mechanism of an increased expression of SHBG is not well understood. However, in vitro and in vivo research in mice suggests that thyrotoxicosis causes an increased expression of HNF4A in liver cells. Thus, upregulating the expression of SHBG. Interestingly, HNF4A is suspected to play an important role in MODY. Future research will clarify the importance of this gene and might open up new insights for therapy.

Metastatic medullary thyroid carcinoma presenting as ectopic Cushing's syndrome

SUMMARY

A 41-year-old male presented to the Emergency Department with a 6-month history of back and hip pain. Skeletal survey revealed bilateral pubic rami fractures and MRI of the spine demonstrated multiple thoracic and lumbar fractures. Secondary work up for osteoporosis was undertaken. There was no evidence of hyperparathyroidism and the patient was vitamin D replete. Testosterone (T) was low at 1.7 nmol/L (8.6-29.0) and gonadotrophins were undetectable. The patient failed a 1 mg dexamethasone suppression test (DST) with a morning cortisol of 570 nmol/L (<50) and subsequently a low dose DST with a cortisol post 48 h of dexamethasone of 773 nmol/L (<50) and an elevated ACTH 98 ng/L. A corticotropin-releasing factor (CRF) test suggested ectopic ACTH secretion. The patient was commenced on teriparatide for osteoporosis and metyrapone to control the hypercortisolaemia. A positron emission tomography (PET) scan to look for the source of ACTH secretion demonstrated right neck adenopathy. Biopsy and subsequent lymph node dissection were performed and histology revealed a metastatic neuroendocrine tumour. Immunostaining was positive for calcitonin and thyroid transcription factor 1 (TTF1). Serum calcitonin was also significantly elevated at 45 264 ng/L (<10). The patient proceeded to a total thyroidectomy and left neck dissection. Histology confirmed a 7 mm medullary thyroid carcinoma (MTC). Post-operatively, the patient commenced vandetanib therapy and achieved a clinical and biochemical response. After approximately 18 months of vandetanib therapy, the patient developed recurrent disease in his neck. He is currently on LOXO-292 and is doing well 36 months post-diagnosis.

LEARNING POINTS

Unexplained osteoporosis requires thorough investigation and the workup for secondary causes is not complete without excluding glucocorticoid excess. MTC should be considered when searching for sources of ectopic ACTH secretion. Resistance to tyrosine kinase inhibitors is well described with MTC and clinicians should have a low threshold for screening for recurrent disease.

Challenges in the functional diagnosis of thyroid nodules before surgery for TSH-producing pituitary adenoma

SUMMARY

A 50-year-old woman with thyroid-stimulating hormone (TSH)-producing pituitary adenoma (TSHoma) was diagnosed due to symptoms of thyrotoxicosis. Preoperatively, she showed thyrotoxicosis with the syndrome of inappropriate secretion of TSH (SITSH) and had a 5 cm nodule in her thyroid gland. Octreotide was administered preoperatively, which helped lower her serum TSH level but not her thyroid hormone level. These findings were atypical for a patient with TSHoma. The TSHoma was completely resected, and the TSH level dropped below the sensitivity limit shortly after surgery. Interestingly, however, thyroid hormone levels remained high. A clear clue to the aetiology was provided by consecutive thyroid scintigraphy. Although preoperative thyroid scintigraphy did not show a hot nodule and the mass was thought to be a non-functional thyroid nodule, the nodule was found to be hot in the postoperative phase of TSH suppression. By focusing on the atypical postoperative course of the TSHoma, we were able to conclude that this was a case of TSHoma combined with an autonomously functioning thyroid nodule (AFTN).

LEARNING POINTS

The diagnosis of autonomously functioning thyroid nodules (AFTNs) depends on suppressed serum TSH levels. If thyroid hormones are resistant to somatostatin analogue therapy or surgery for TSHoma, complications of AFTN as well as destructive thyroiditis need to be considered. It is important to revisit the basics when facing diagnostic difficulties and not to give up on understanding the pathology.

B cell targeting by molecular adjuvants for enhanced immunogenicity

INTRODUCTION

Adjuvants are critical components of vaccines to improve the quality and durability of immune responses. Molecular adjuvants are a specific subclass of adjuvants where ligands of known immune-modulatory receptors are directly fused to an antigen. Co-stimulation of the B cell receptor (BCR) and immune-modulatory receptors through this strategy can augment downstream signaling to improve antibody titers and/or potency, and survival in challenge models.

AREAS COVERED

C3d has been the most extensively studied molecular adjuvant and shown to improve immune responses to a number of antigens. Similarly, tumor necrosis superfamily ligands, such as BAFF and APRIL, as well as CD40, CD180, and immune complex ligands can also improve humoral immunity as molecular adjuvants.

EXPERT OPINION

However, no single strategy has emerged that improves immune outcomes in all contexts. Thus, systematic exploration of molecular adjuvants that target B cell receptors will be required to realize their full potential as next-generation vaccine technologies.

An LGG-derived protein promotes IgA production through upregulation of APRIL expression in intestinal epithelial cells

p40, a Lactobacillus rhamnosus GG (LGG)-derived protein, transactivates epidermal growth factor receptor (EGFR) in intestinal epithelial cells, leading to amelioration of intestinal injury and inflammation. To elucidate mechanisms by which p40 regulates mucosal immunity to prevent inflammation, this study aimed to determine the effects and mechanisms of p40 on regulation of a proliferation-inducing ligand (APRIL) expression in intestinal epithelial cells for promoting immunoglobulin A (IgA) production. p40 upregulated April gene expression and protein production in mouse small intestine epithelial (MSIE) cells, which were inhibited by blocking EGFR expression and kinase activity. Enteroids from Egfr^fl/fl, but not Egfr^fl/fl-Vil-Cre mice with EGFR specifically deleted in intestinal epithelial cells, exhibited increased April gene expression by p40 treatment. p40-conditioned media from MSIE cells increased B-cell class switching to IgA⁺ cells and IgA production, which was suppressed by APRIL receptor-neutralizing antibodies. Treatment of B cells with p40 did not show any effects on IgA production. p40 treatment increased April gene expression and protein production in small intestinal epithelial cells, fecal IgA levels, IgA⁺B220⁺, IgA⁺CD19⁺, and IgA⁺ plasma cells in lamina propria of Egfr^fl/fl, but not of Egfr^fl/fl-Vil-Cre, mice. Thus p40 upregulates EGFR-dependent APRIL production in intestinal epithelial cells, which may contribute to promoting IgA production.

TGF-β1 stimulates mouse macrophages to express APRIL through Smad and p38MAPK/CREB pathways

A proliferation-inducing ligand (APRIL), a new TNF family member, supports B-cell survival and tumor cell proliferation. APRIL is secreted as a soluble protein by macrophages, dendritic cells and activated T cells. However, factors involved in regulation of APRIL expression are as yet unknown. In this study, we investigated the effect of TGF-β1 on APRIL expression in P388D1, a mouse macrophage cell line. TGF-β1 induced APRIL mRNA expression in a time- and dose-dependent manner. One nanogram per milliliter of TGF-β1 was optimal and APRIL transcripts appeared as early as 3 h after stimulation. Based on our studies, which included overexpression of Smad3, DN-Smad3, and sh-Smad3, we found that Smad3 mediates APRIL transcription at least partially. Further, experiments using inhibitors revealed that p38MAPK and CREB are also involved in TGF-β1-induced APRIL expression. These results suggest that TGF-β1, through Smad3 and p38MAPK/CREB signaling pathways, stimulates APRIL expression in macrophages.

SLE--systemic lupus erythematosus: a BLySful, yet BAFFling, disorder

BLyS/BAFF (B-lymphocyte stimulator/B-cell activating factor) is a vital B-cell survival factor. Overexpression of BLyS in mice may lead to systemic-lupus-erythematosus-like (SLE-like) disease, and BLyS overexpression is common in human SLE. Treatment of SLE-prone mice with a BLyS antagonist ameliorates disease progression and enhances survival, making BLyS an attractive therapeutic target in human disease. However, several unresolved issues remain, including what is the contributory role of APRIL (a tumor-necrosis-factor superfamily member related to BLyS) in the 'autoimmunogenic' effects of BLyS, identification of the 'optimal' BLyS antagonist, and identification of those SLE patients most likely to benefit from BLyS antagonist therapy.