• inflammatory bowel disease
• erythema nodosum
• calprotectin

A 12-year-old girl was admitted to the paediatric ward with a 5-week history of increasing tiredness. Her mother noted that she looked pale and had began to lose her hair. Her mother described that she had been complaining of a painful ‘cyst’ in her perineal area which was discharging pus. She also complained of a painful swollen right elbow which had appeared spontaneously in absence of any trauma. On questioning, she revealed that ‘9 out of 10’ of her bowel motions contained dark red blood mixed in with stool.

On examination, the patient appeared lethargic with generalised pallor. Angular stomatitis and aphthous ulcers on the buccal mucosa were noted. Her abdomen was soft, non-tender with no masses palpable. Her perineum was inspected with a chaperone, which revealed a vulva ulcer at the 11 o'clock position with active bleeding. Multiple skin tags were noted in the perianal area. Musculoskeletal examination demonstrated a tender, swollen, warm but non-erythematous left elbow with restricted range of motion (ROM) …