Pituitary disorders are a common endocrine problem. Rarely non-endocrine pathology can manifest with pituitary symptoms, leading to delays in accurate diagnosis and treatment.
We report a case of a 46-year-old female, with a 30-pack-year smoking history, who presented with unilateral visual disturbance and headaches. This was on the background of chronic diarrhoea and weight loss. She also reported polyuria, polydipsia, spontaneous galactorrhoea and amenorrhea since cessation of contraception five months prior. She had preserved visual field testing.
Bloods revealed an early morning cortisol of 274 nmol/L[N 140 – 640], ACTH 24 ng/L[N 10-50], TSH 1.4 mU/L[N 0.3-4.5], IGF-1 22nmol/L[N 8.3-32], and Prolactin 1570 mU/L[N 71-566]. A 24-hour urine collection confirmed polyuria with an output of 3.6 litres. MRI noted a pituitary mass(18 x 21 x 16mm) with no other abnormalities. She was subsequently commenced on carbegoline. 12 days later she presented with vomiting and new transaminitis. Her admission was rapidly complicated by respiratory distress and hypotension, with urgent echocardiography revealing cardiac tamponade. 800mL of blood-stained fluid was drained by emergency pericardiocentesis. Repeat prolactin had normalised (8 mU/L). Serial MRI during her admission revealed interval increase in the pituitary mass with encroachment into the suprasellar cistern and small areas of necrosis within the lesion. Cytology from pericardial fluid showed non-small cell carcinoma with subsequent pan computed tomography revealing a right apical lung lesion, extensive mediastinal adenopathy and an adrenal metastasis.
Pituitary metastasis is rare, with an occurrence rate between 1-3.6% (1). Breast and lung cancer are the most common sources (1,2). Even rarer are symptomatic presentations of pituitary metastasis, with one series suggesting 7% (2).
This case highlights a common endocrine problem masquerading as metastatic malignancy which manifested as cardiac tamponade. Diagnosis can often be delayed due to constitutional malignant symptoms that can mimic pituitary dysfunction.