Endocrine Abstracts

JOINT3915

Background: Tuberous sclerosis complex (TSC) is a rare inherited neurocutaneous disorder characterised by a diverse range of benign growths, or hamartomas, affecting multiple organ systems. These can involve the brain, eyes, heart, lungs, liver, kidneys, and skin. The expression of TSC varies considerably between individuals. Clinical diagnosis is typically supported by imaging and genetic testing, with characteristic brain lesions such as glioneuronal hamartomas, subependymal nodules, subependymal giant cell astrocytomas, white matter lesions, and arachnoid cysts being commonly observed. Pituitary stalk interruption syndrome PSIS is diagnosed primarily through magnetic resonance imaging (MRI) of the brain which shows the characteristic abnormalities of the pituitary stalk and posterior pituitary location, while TSC diagnosis often involves genetic testing, clinical evaluation, and imaging studies to identify the characteristic brain lesions. Though both of TSC and pituitary stalk interruption syndrome (PSIS) is rare, the co-occurrence of these two conditions is even less frequent.

Clinical Case Description: A 41-year-old female with a medical history of TSC presented with polydipsia and polyuria. Laboratory tests revealed hypernatremia, alongside highly diluted urine, which led to a diagnosis of arginine vasopressin deficiency (AVP-D) (diabetes insipidus). The patient’s history of TSC included bilateral renal angiomyolipomas (AML), learning difficulties, epilepsy, autism, and lymphangioleiomyomatosis affecting the lungs, kidneys, and lymphatic system. Upon initiation of Desmopressin treatment, her sodium levels normalised, and her carers reported significant improvement in her symptoms, including a reduction in excessive thirst and inappropriate fluid intake. In the past, she had been observed licking condensation from windows due to her heightened thirst. MRI of the pituitary gland, performed under sedation, revealed a hypoplastic anterior pituitary, an absent infundibulum, and agenesis of the posterior pituitary gland, findings that are consistent with pituitary stalk interruption syndrome (PSIS). Notably, the anterior pituitary profile was unremarkable.

Conclusion: This case highlights the rare and complex interplay between TSC and PSIS, the occurrence of both in a single patient is uncommon. Further research into the genetic mechanisms behind these conditions may provide insights into their co-occurrence and potential management strategies.