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Open access

Mara Ventura, Leonor Gomes, Joana Rosmaninho-Salgado, Luísa Barros, Isabel Paiva, Miguel Melo, Diana Oliveira and Francisco Carrilho

Summary

Intracranial germinomas are rare tumors affecting mostly patients at young age. Therefore, molecular data on its etiopathogenesis are scarce. We present a clinical case of a male patient of 25 years with an intracranial germinoma and a 16p11.2 microdeletion. His initial complaints were related to obesity, loss of facial hair and polydipsia. He also had a history of social-interaction difficulties during childhood. His blood tests were consistent with hypogonadotropic hypogonadism and secondary adrenal insufficiency, and he had been previously diagnosed with hypothyroidism. He also presented with polyuria and polydipsia and the water deprivation test confirmed the diagnosis of diabetes insipidus. His sellar magnetic resonance imaging (MRI) showed two lesions: one located in the pineal gland and other in the suprasellar region, both with characteristics suggestive of germinoma. Chromosomal microarray analysis was performed due to the association of obesity with social disability, and the result identified a 604 kb 16p11.2 microdeletion. The surgical biopsy confirmed the histological diagnosis of a germinoma. Pharmacological treatment with testosterone, hydrocortisone and desmopressin was started, and the patient underwent radiotherapy (40 Gy divided in 25 fractions). Three months after radiotherapy, a significant decrease in suprasellar and pineal lesions without improvement in pituitary hormonal deficiencies was observed. The patient is currently under follow-up. To the best of our knowledge, we describe the first germinoma in a patient with a 16p11.2 deletion syndrome, raising the question about the impact of this genetic alteration on tumorigenesis and highlighting the need of molecular analysis of germ cell tumors as only little is known about their genetic background.

Learning points:

  • Central nervous system germ cell tumors (CNSGTs) are rare intracranial tumors that affect mainly young male patients. They are typically located in the pineal and suprasellar regions and patients frequently present with symptoms of hypopituitarism.

  • The molecular pathology of CNSGTs is unknown, but it has been associated with gain of function of the KIT gene, isochromosome 12p amplification and a low DNA methylation.

  • Germinoma is a radiosensitive tumor whose diagnosis depends on imaging, tumor marker detection, surgical biopsy and cerebrospinal fluid cytology.

  • 16p11.2 microdeletion syndrome is phenotypically characterized by developmental delay, intellectual disability and autism spectrum disorders.

  • Seminoma, cholesteatoma, desmoid tumor, leiomyoma and Wilms tumor have been described in a few patients with 16p11.2 deletion.

  • Bifocal germinoma was identified in this patient with a 16p11.2 microdeletion syndrome, which represents a putative new association not previously reported in the literature.

Open access

Alicia R Jones, Alan McNeil, Christopher Yates, Bala Krishnamurthy and Peter S Hamblin

Summary

A variety of neoplastic, inflammatory and congenital conditions can cause pituitary stalk thickening. Differentiating between these causes is important as targeted treatment may be offered. Diagnostic work-up consists of a thorough history, examination, biochemical analysis and imaging. We present the case of a 33-year-old male who presented with diabetes insipidus and had pituitary stalk thickening on magnetic resonance imaging. Further investigations revealed an elevated CSF βhCG, which raised the possibility of an intracranial germ cell tumor. However, when repeated on four different assays, the βhCG levels were discordant. On serial imaging, the pituitary stalk thickening reduced slightly, which would be unexpected for a germ cell tumor. This case raises the difficulties interpreting CSF βhCG, as not all immunoassays for βhCG have been validated for use in CSF. The Roche Diagnostics Elecsys and Siemens Centaur assays have been validated for CSF βhCG, and so we advocate using one of these methods. If unavailable or serum/CSF results are ambiguous, serial MRI is appropriate, with pituitary stalk biopsy considered if the stalk measures >6.5 mm or other imaging abnormalities are present.

Learning points:

  • Most adult patients with central diabetes insipidus have imaging abnormalities on a pituitary MRI. The most common abnormalities are loss of the posterior pituitary bright spot and pituitary stalk thickening, both of which are non-specific.

  • Causes of pituitary stalk thickening include neoplastic, inflammatory, infective and congenital lesions.

  • Investigation of pituitary stalk thickening should encompass the many possible causes and include biochemical analyses as well as imaging of the chest, abdomen and pelvis. Further investigations should be guided by the clinical context, but may include testicular ultrasound, CSF analysis and pituitary stalk biopsy.

  • Germ cell tumors involving the pituitary stalk may be suspected on clinical grounds, but in the absence of a tissue diagnosis (biopsy) confirmation may be difficult and relies on biochemical assessment of blood and possibly CSF as well as serial MRI imaging.

  • CSF βhCG levels should be analyzed on an instrument validated for use in CSF or on multiple instruments, and the pitfalls of testing this marker (false negative in some germ cell tumors, false positives in other conditions, lack of internationally agreed reference ranges for diagnosing germ cell tumors) should be considered when interpreting the results.

Open access

Rayna Patel, Waheed Mustafa, Michael T Sheaff and Sami Khan

Summary

IgG4-related disease (IgG4-RD) is a rare but increasingly recognised condition, emerging as a clinical entity following the observation of the associations of autoimmune pancreatitis. IgG4-RD is characterised by extensive infiltration of IgG4-positive plasma cells into multiple organs and raised serum IgG4 levels. Clinical manifestations of IgG4 disease classically include autoimmune pancreatitis, lacrimal or salivary gland infiltration (formerly known as Mikulicz disease) and retroperitoneal fibrosis. More rarely, IgG4 disease can cause pituitary hypophysitis. Although most frequently described in middle-aged males, the epidemiology and pathogenesis of the disease remain largely undefined. Nevertheless, an understanding of the wide variety of clinical manifestations of this multi-system condition is undeniably important given the often excellent outcomes following treatment. We describe an unusual presentation of IgG4 disease with isolated diabetes insipidus secondary to pituitary hypophysitis. The patient in question subsequently developed chest pain secondary to mediastinal lymphadenopathy and tubulo-interstitial nephritis leading to renal dysfunction. He was successfully treated with oral steroids and had regular follow-up, and remains well at follow-up 2 years later.

Learning points

  • IgG4 disease, although rare, is increasing in prevalence largely due to increased recognition of its clinical manifestations, including autoimmune pancreatitis, lacrimal or salivary gland infiltration, retroperitoneal fibrosis and, more rarely, lymphocytic hypophysitis presenting as diabetes insipidus.

  • IgG4 disease is highly treatable, and symptoms may show complete resolution with administration of steroids, highlighting the importance of correct and timely diagnosis.

  • Causes of lymphocytic hypophysitis are varied and not distinguishable radiologically. Given the difficulty in biopsying the pituitary, careful attention must be paid to the systemic clinical presentation to provide clues as to the underlying disorder.