In this patient, abdominal CT scan revealed a large retroperitoneal solid mass heterogeneously enhanced after contrast injection (Fig. 1). This mass was centered on the inferior under renal vena cava which was no more individualized. It had irregular borders and was associated with iliac veins thrombosis. It invaded the lumbar segment of right ureter. It invaded the right psoas muscle and was in contact with the spine. Onward, it came in contact with the third duodenum. The inferior vena cava above renal was permeable (Fig. 2).
The patient underwent CT-guided needle core biopsy. Histological examination showed a malignant mesenchymal proliferation. An immunohistochemical study was performed. Morphological and immunohistochemical features were consistent with leiomyosarcoma1,2.
Answer to question: b.
Diagnosis: Histológico (biopsia guiada por TC): Leiomiosarcoma.