Case presentation

A 66-year-old man presented with chronic watery diarrhoea and progressive weight loss (~15 kg) over 6 months, accompanied by dysgeusia, hair loss, skin hyperpigmentation and onychodystrophy affecting both fingers and toes. He also developed lower limb oedema 4 days before admission. He denied fever, abdominal pain or bloody stools. Physical examination revealed sparse hair, diffuse brown pigmentation over limbs and yellow dystrophic nails (figure 1). Initial laboratory tests showed hypoalbuminaemia (19.3 g/L), hypokalaemia (2.53 mmol/L), hypocalcaemia (1.43 mmol/L) and recurrent electrolyte disturbances. Stool occult blood was weakly positive but no evidence of infection (negative stool culture, HIV, HBV, HCV, cytomegalovirus (CMV)). Upper endoscopy revealed diffuse nodular and polypoid changes in the stomach and duodenum (figure 2A–C). Colonoscopy showed hundreds of polyps throughout the colon and terminal ileum with erythematous mucosa (figure 2D–F). Capsule endoscopy confirmed extensive polypoid lesions with white, elongated villi, mucosal oedema and lymphangiectasia throughout the…