Behçet Disease Oral Aphthous Ulcers

A 32-year-old man from Turkey presents with recurrent painful oral ulcers over the past 18 months. The lesion marked **A** in the diagram shows a sharply demarcated ulcer with a yellow-white fibrinous base and erythematous halo on the buccal mucosa. He also reports a history of genital ulceration and intermittent eye pain with photophobia. Serological tests are negative for HSV and aphthous stomatitis minor. A pathergy test performed with a sterile needle prick shows a papule at 48 hours. Which of the following best characterizes the underlying pathophysiology of the recurrent oral aphthous ulceration marked **A** in this patient?