Retroperitoneal leiomyosarcoma

Last revised by Joshua Yap on 11 May 2023

Retroperitoneal leiomyosarcomaleiomyosarcoma arising within the retroperitoneum, is one of the commonest primary retroperitoneal neoplasms. The retroperitoneum is considered the most common extrauterine site for leiomyosarcoma. 

They are more common in women.

Symptoms are often non-specific with abdominal pain being one of the most frequent complaints. The tumors can reach large sizes at the time of detection. 

They arise from smooth muscle within arteries, veins, or bowel.

The most frequent site is the inferior vena cava (50%), which is discussed separately: inferior vena cava leiomyosarcoma.

They can be:

  • completely extravascular: 62%

  • completely intravascular: 5%

  • have extraluminal and intraluminal components: 33%

Metastases to the liver and lung are common when the tumor is intravascular.

Like other sarcomas, imaging findings are non-specific. Retroperitoneal leiomyosarcomas tend to develop massive cystic components which undergo degeneration. Unlike other sarcomas, fat and calcification are not typically present.

Contiguous involvement of a vessel may clear and would favor this over other types of sarcoma. 

  • T1: intermediate to low signal intensity

  • T2: intermediate to high signal intensity

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