A young man presents reporting diarrhea, fecal urgency, and weight loss. his stool is light-coloured and malodorous, and it tends to float and be difficult to flush. he has also noted tender, red bumps on his shins and reports pain and stiffness in his elbows and knees. sigmoidoscopy reveals discontinuous, granulomatous lesions; no blood is detected in his stool. which diagnosis would his care team first suspect?