Small Intestinal Adenocarcinoma Presenting With Internal High Echoes: A Case Report

An 82-year-old female was referred to our hospital due to repeated vomiting. CT showed a heterogeneously enhanced mass, 50 mm in size, with cavitation in the lower abdomen. Ultrasound revealed a well-circumscribed polygonal mass with internal high echoes. Positron emission tomography (PET) of the target mass showed a maximal standardized uptake value of 18.6. Single-balloon endoscopy, however, failed to directly visualize the mass. Although serum CEA and CA19-9 levels were within normal ranges, sIL-2R was slightly elevated at 954 U/mL. Ultrasound findings, however, prompted us to operate on the target mass under the tentative diagnosis of ileal adenocarcinoma. The operation revealed that the tumor was located in the terminal ileal diverticulum and involved the surrounding small intestine. The diverticulum was not Meckel's diverticulum and was located on the mesentery side. The mass did not pathologically contain any ectopic tissues and had atypical cells, mainly growing in a tubular fashion at the epithelium and in a cribriform fashion in the muscular propria. Immunostaining showed positivity for CK7 and CDX2, partial positivity for MUC5AC, and negativity for CK20, CD10, CD56, synaptophysin, and chromogranin. These pathological findings led to the diagnosis of ileal moderately-differentiated adenocarcinoma. The patient recovered uneventfully, was discharged on the 10th day after surgery, and was scheduled for outpatient follow-up without adjuvant chemotherapy given her advanced age. Diagnostic physicians should note that moderately- or well-differentiated adenocarcinomas have internal high echoes, which can be an important diagnostic clue for the differential diagnosis of small intestinal tumors.