A 48-year-old woman was admitted to our hospital due to abdominal pain and distension for one month, diarrhea for three weeks, and urological symptoms including dysuria, frequency and urgency for one week. Watery stools were 3-5 times a day, without blood. She complained of associated fever with a maximum temperature of 39℃. She also reported with obvious weight loss of a month duration.
Laboratory findings on admission revealed the following: hemoglobin 97g/L (normal range, 115~150 g/L); white blood cells(WBC) 7.47×109/L (normal range, 3.5~9.5×109/L) with 83.5% neutrophils (normal range, 40%~75%) and lymphocytes 9.6% (normal range, 20%~50%); C-reactive protein 118mg/L (normal range, <8.20mg/L). Routine stool test showed yellow, mushy, occult blood ±. Urinalysis showed red blood cells of 199/hpf and WBC of 10/hpf (normal range, 0~2/hpf). Serum neuron specific enolase was 27.20ng/ml (normal range, <16.3ng/ml) and carbohydrate antigen 125 was 52.80U/ml (normal range, <35ng/ml). Patient tested negative for HIV.
Initially, the patient underwent an abdominal MRI (Fig 1, 2). It demonstrated that varied thickening wall of entire small bowel, part of colon, and rectum with iso or hypo-intensity on T2WI, reduced diffusion on DWI, whereas low signal intensity on ADC map, and markedly homogeneous enhancement. In order to make a comprehensive assessment, a whole-body PET/CT (Fig 1, 2) was performed. The maximum intensity projection (MIP) showed the intestine in the left side of abdomen and pelvic cavity with diffuse increased FDG-activity, the spleen (SUVmax 4.8~5.3) and skeleton (SUVmax 7.6~8.8) were also with diffuse FDG-avid. The coronal CT and fused PET/CT revealed diffuse wall thickening of entire small bowel, part of colon and rectum with increased FDG-uptake (SUVmax 4.0~10.2), obviously in the proximal jejunum that showed a thick-walled prominent dilated loop with an air-fluid level. There were some swollen mesenteric lymph nodes with increased FDG-uptake (SUVmax 3.3~5.7). Multiple low-density lesions were FDG-avid (SUVmax 4.4~8.8) in the liver.
Given the high suspicion for malignancy, the patient underwent gastrointestinal endoscopes and histopathology. The results showed extensive ulcerations in the gut (Fig 3), and the result of biopsy pathology were suggestive of MEITL (Fig 3). The lymphoma cells are small to medium-sized, and monomorphic, expressing characteristically CD3, CD8, CD56 and so on, Ki-67 value of this patient was around 40%. Bone marrow biopsy demonstrated no evidence of lymphoma involvement.
MEITL is a primary intestinal T-cell lymphoma caused because of malignant proliferation of intraepithelial lymphocytes[2]. The most common site is small bowel, followed by large bowel, stomach, with frequent involvement of mesenteric and para-aortic or iliac lymph nodes. It can spread to lung (lesions are often accompanied with necrosis), liver, prostatic and central nervous system[2-5]. The SUVmax of all lesions in our case varied from 3.3 to 10.2, which was similar to Chan’s report[1]. On PET/CT, MEITL needs to be differentiated from EATL and some aggressive B-cell lymphomas. EATL occurs as hypermetabolic lesions with high SUVmax, against a background of diffuse FDG accumulation of mild SUVmax evolving from refractory coeliac disease[5]. The SUVmax in B-cell lymphoma were generally obviously higher than those of MEITL[6]. Unfortunately, the prognosis of MEITL is extremely poor with a reported median survival of only seven months and one-year overall survival is only 36%[7], which is mostly due to late diagnosis and lack of targeted therapy. This patient died 3 months after she was diagnosed with MEITL.