[The role of ultrasonography in the diagnosis and staging of gastroenteric lymphoma].

Ultrasonography (US) plays an important role in the diagnosis, staging and follow-up of gastrointestinal lymphomas particularly when associated with complementary techniques such as echo-guided biopsy and endoscopic ultrasonography. Besides the well-known ultrasonographic "pseudo-kidney" image as sign of gastrointestinal pathology, the "spoke wheel" image is suggestive of gastroenteric lymphoma. This lesion is due to the lymphomatous infiltration of intestinal wall that looks ipoechoic compared to the iperechoic lumen. An early abdominal US study performed after clinical suspicion, should allow a presumptive identification of the enteric tract involved on the basis of the relationship between the "pseudokidney" image and the other abdominal organs. US study of the abdomen may be useful also to demonstrate enlarged retroperitoneal or visceral lymph nodes both in primary gastroenteric or systemic lymphomas. Fine needle biopsy (FNB) of deep lymph nodes is mandatory when superficial enlarged lymph nodes are not found showing a specificity and sensitivity of 100% and 66% respectively. The typical image of gastric wall on endoscopic US is constituted of five layers; the second one represents the lamina propria with the lymphatic tissue. The thickness increase of this layer suggest the diagnosis of gastric lymphoma. Therefore the endoscopic US examination is particularly important when the endoscopic features and the endoscopic biopsies are negative. Finally endoscopic US may be used to guide FNB of gastrointestinal tract lesions.