Leiomyosarcoma

Leiomyosarcomas are extremely rare malignant neoplasms that originate from smooth muscle cells and may be considered the malignant counterpart of a leiomyoma. They are classified as soft-tissue tumors and account for approximately 8% of malignant soft-tissue tumors ¹⁰.

Pathology

Location 

Leiomyosarcomas can potentially occur anywhere there is smooth muscle. Commonly described sites include the following:

• uterus: uterine leiomyosarcoma: most common, (accounting for up to one-third of uterine sarcomas ⁸)

• retroperitoneum: retroperitoneal leiomyosarcoma; most common non-uterine site ¹¹

• stomach ¹: gastric leiomyosarcoma

• esophagus ⁵: esophageal leiomyosarcoma  

• small intestine: leiomyosarcoma of the small intestine 

• liver: hepatic leiomyosarcoma

• bladder

• nasopharynx 

• bone ⁶: primary leiomyosarcoma of bone

• venous structures ¹⁰

  • inferior vena cava leiomyosarcoma

  • pulmonary artery leiomyosarcoma

• central nervous system: primary intracranial leiomyosarcoma

Other sites include:

• spermatic cord: spermatic cord leiomyosarcoma

• pulmonary artery: primary pulmonary artery leiomyosarcoma

• skin: cutaneous leiomyosarcoma ¹³

Radiographic features

Morphological imaging features would be invariably dependent on the site (refer to individual articles). Generally, they tend to be large masses, especially in cases of abdominopelvic lesions.

CT

• generally heterogeneous

• commonly demonstrate central low attenuation representing necrosis ¹²

• calcification exceedingly rare

MRI

The tumor frequently demonstrates cystic foci. Signal characteristics include:

• T1: isointense to muscle 

• T2 non-fat suppressed: intermediate to hypointense to neighboring fat 

• T2 FS: predominantly hyperintense 

Differential diagnosis

For a meaningful differential, it is necessary to consider site-specific tumors.