Littoral cell angioma mimicking hepatic tumor
A 53-year-old woman presented with a 10-year history of intermittent abdominal pain, swelling and continuous vomiting. The patient denied presence of fever, nausea, and weight loss. There were no significant findings at physical examination. An abdominal ultrasound exam revealed a 10.4 × 10.0 cm mass of heterogeneous echogenicity in the left upper abdomen. Axial unenhanced CT scan (Fig. a) confirmed an ill-defined heterogeneous mass 9.1 cm in diameter that filled the left abdominal quadrant, located between the left lobe of the liver and the spleen. The CT attenuation of the mass was around 26–53 HU on non-enhanced scan. After intravenous contrast medium injection the mass enhanced gradually and heterogeneously (Fig. b–e), but was still hypodense relative to the spleen. There was no accompanying lymphadenopathy or evidence of malignant process elsewhere in the abdomen. Because the origin of the mass was unknown and a primary malignancy could not be excluded, the patient underwent an explorative laparotomy. During the operation, a well-encapsulated mass was found under the left hepatic lobe and the pedicle arising from the spleen. Resection of the mass and the spleen was performed.\nGross examination of the spleen showed splenomegaly (580 g, 15 × 10 × 9 cm) with an ill-defined brownish nodule (5 × 8 × 8 cm). Histologic examination (Fig. ) revealed that the lesion was composed of variably sized vascular channels lined with flat and tall endothelial cells, with papillary fronds extending into the vascular channels. No atypical cells or mitosis were present. The endothelial lining cells of the vascular channels were positive for CD31 and CD68, factor VIII and negative for CD34, CD21, and CD8. These findings were considered diagnostic of benign splenic littoral cell angioma.