A 31-year old Yemeni man was admitted to King Faisal Specialist Hospital and Research Centre with a chief complaint of persistent abdominal pain of 3 years' duration. The pain was steady with super-imposed postprandial colicky bouts felt mainly in the periumbilical region. Nausea with occasional vomiting was present. Six months prior to admission he began having soft, watery stools two or three times per day. During this time he lost about 15 kg. He had no rash, arthralgia, melena, cough or fever.Physical examination revealed him to be thin, active, and anxious. Temperature was 36.5°C. Blood pressure was 100/60 mmHg. Clubbing of fingertips was evident. There was no lymphadenopathy, abdominal masses or hepatosplenomegaly. Heart and lungs were normal. Intestinal peristalsis was active. Results of rectal and sigmoidoscopic examinations were normal. Laboratory studies were as follows: Hematocrit 39 percent with RBC mean corpuscular volume of 66 cu microns and a mean corpuscular hemoglobin of 20 pg. White blood count was 7300/mm 3 with 54 percent lymphocytes, of which 4 percent were atypical. Serum iron was 10 μg/dl and total iron binding capacity 150 μg/dl. Results of the D-xylose absorption test were normal. Serum vitamin B12 and folic acid levels were normal. No occult blood, ova, or parasites were found in the stools on three occasions. Sudan III stain of the stools revealed from 75 to more than 100 globules of fat per low power field. Serum albumin was 2.2 gm/dl, serum globulins 2.4 gm/dl, and SGPT 40 to 60 U/ml. Alkaline phosphatase ranged between 59 and 140 units; alkaline phosphatase isoenzymes were predominantly of liver origin. Levels of lactic dehydrogenase, total bilirubin, direct bilirubin, creatine phosphokinase, uric acid, serum phosphorus, and blood urea nitrogen were normal. Blood cholesterol was 127 mg/dl. Pancreatic ultrasonography and liver and bone radionuclide scans were normal. Lymphangiography was attempted but was unsuccessful. Barium enema findings were normal. An upper GI series and small intestinal study showed coarsened small bowel mucosal folds with intervening normal-looking segments. Tuberculin testing with PPD produced a 3-cm indurated erythematous nodule after 24 hours. Rectal biopsy showed normal mucosa.The patient's temperature ranged between normal and 38.2°C with occasional elevation to 39°C and sweating. A laparotomy on the 10th hospital day revealed normal liver, stomach, spleen and colon. The small intestine had long thickened segments with occasional normal segments. Numerous large lymph nodes were present in the mesentery, one of which was excised along with the appendix. The lymph node showed reactive hyperplasia. Occasional noncaseating granulomas were present in the serosa and muscularis of the appendix. No acid-fast bacilli, fungi or parasitic ova were found in the granulomas. There was a neutrophilic exudate in the lumen of the appendix in one section. No malignant lymphoma was noted in these specimens. On the seventh postoperative day a peroral small intestinal biopsy ...