Perforation of jejunal lymphoma--ultrasonographic diagnosis of free air over left flank area.

Acute abdomen due to perforation of one of the hollow organs is one of the major challenges for clinicians. Traditionally, pneumoperitoneum shown on X-ray film taken of the decubitus view or in the standing position, is the major key to making a diagnosis of perforation. However, free air is not shown on X-ray film in about one third of cases and sometimes, a standing X-ray cannot be taken in weak patients or for various reasons. In such conditions, abdominal ultrasonography (US) plays a complementary role. Free air is usually detected between the anterior surface of the liver and the anterior abdominal wall by US. However, if free air is not detected on an erect X-ray or not demonstrated over the anterior surface of the liver by US, the diagnosis of perforation of the hollow organ will be difficult. We treated a patient with perforation of a small intestinal lymphoma, which presented as free air over the left flank area by US rather than the anterior surface of liver as is usually the case. Moreover, we located the perforated site pre-operatively by US, which detected focal thickening of a segment of small intestine with intramural slits. Lymphoma of the jejunum with perforation was finally diagnosed after surgery. The value of US is justified in such a condition.