This is a case report of amyloid goitre in a 40-year-old female patient with cystic fibrosis (CF), complicated by chronic suppurative and obstructive lung disease, pancreatic insufficiency, malabsorption, and CF related diabetes mellitus (CFRD). She presented to the CF clinic in 2010 with new onset goitre. She was clinically and biochemically euthyroid. Thyroid ultrasound in May 2010 confirmed the presence of a dominant thyroid nodule measuring 3.5x3.5x1.5cm in the right lobe extending to the isthmus. The nodule had normal vascular signature. Fine needle aspiration biopsy (FNAB) cytology was reported as benign follicular pattern with some cystic degeneration.

Repeat ultrasound 12 months later demonstrated significant nodular enlargement (5.4x4.3x2.9cm), which replaced the right lobe and extending into the isthmus. The nodule was now non-vascular, poorly defined, and isoechoic. Repeat FNAB demonstrated benign cystic degeneration in a colloid nodule (Bethesda Category II). The patient declined the thyroidectomy recommendation secondary for fear of reduced lung clearance post-surgery.

Concurrently, the patient was diagnosed with renal amyloidosis in June 2012 (from increasing microalbuminuria). This raised the suspicion of thyroid amyloidosis. Because of worsening airway symptoms during an infective exacerbation of lung disease, and dysphagia, total thyroidectomy was performed in October 2012. The right lobe of thyroid weighed 42g and left lobe weighed 7g. Microscopy and Congo red staining demonstrated widespread amyloidosis in the thyroid.

Thyroid goitre secondary to amyloidosis is rare. Although thyroid amyloidosis has been reported in patients with chronic suppuratives lung diseases such as bronchiectasis, there are only two reported cases in living adult cystic fibrosis patients^1 2 . This is likely secondary to the shorter life expectancy in CF. Hence, with improved supportive therapy and life expectancy, amyloidosis needs to be considered as a potential disease process in patients with CF.