A 20-year-old woman was hospitalized in the digestive department on February 24, 2020, because of abdominal pain and diarrhea for 3 days and bloody stool for 11 hours. The history of the present illness was further investigated. The patient experienced intermittent pain and discomfort in the right lower abdomen without obvious induction 7 months prior and recurrent aphthous ulcer in the mouth and vulva 6 months prior. More than two months ago, nodular erythema recurred on both sides of the shank without induction. In the past two months, the weight dropped by 2.5 kg. Laboratory test results were as follows: fecal occult blood test, positive; HGB, 78 g/L; ESR, 46 mm/h; CRP, 38.5 mg/L. No abnormalities were found in the stool bacterial culture, infection, tumor, or other immunological indices. Paired test results were positive. Abdominal CT revealed a suspected incomplete intestinal obstruction. On February 25, 2020, enteroscopy showed scattered multiple round ulcers of approximately 0.6-2.0 cm that could be seen in the ileum, which were characterized by white moss and obvious edema of the surrounding mucosa ( Figure 1B ). The biopsy results of the large ulcers showed that the acid-fast bacilli microscopic examination and Mycobacterium tuberculosis rpoB gene examination were negative, and the pathology showed acute and chronic mucosal inflammation.
On March 4, 2020, the patient was transferred to the rheumatology department for further treatment. She was diagnosed with severe intestinal BS, with a DAIBD score of 105. The patient was treated with prednisone (30 mg PO daily), azathioprine (ASA, 100 mg PO daily), and SASP. Two weeks later, AZA was stopped due to a decrease in leukocyte levels, which was switched to cyclophosphamide (CTX, 100 mg PO once every other day) after the recovery of leukocyte levels. After 3 months, prednisone was gradually decreased to 10 mg daily. Although the oral ulcer, vulvar ulcer, and nodular erythema significantly improved, the pain persisted in the right lower abdomen. Therefore, the treatment combined with thalidomide was based on the original treatment.
In September 2020, enteroscopy revealed that the ileal ulcer had not healed. Therefore, CTX was discontinued and the patient was switched to TOF (5 mg PO twice a day). Three months later, enteroscopy revealed that the ileal ulcer had healed. In March 2021, the prednisone dose was gradually reduced to zero. In July 2021, TOF was adjusted to 5 mg daily. THD was discontinued in October 2021. To date, the patient's DAIBD score, ESR, and CRP level have been in remission ( Figure 2 ).