Leiomyoma

Leiomyomas are very common benign smooth muscle tumours. They fit into the soft tissue group of lesions.

General

• Often called "fibroids".
• Extremely common... 40% of women by age 40.
• Benign.
  • Can be a cause of AUB (abnormal uterine bleeding).
  • Large & multiple associated with infertility.

Gross

• Sharply circumscribed.
• Gray-white.
• Whorled appearance.

Factor that raise concern for leiomyosarcoma:

• Haemorrhage.
• Cystic degeneration.
• Necrosis.

Microscopic

Features:

• Spindle cells arranged in fascicles.
  • Fascicular appearance: adjacent groups of cells have their long axis perpendicular to one another; looks somewhat like a braided hair that was cut.
• Whorled arrangement of cells.

Negatives:

• Necrosis (low power) - suggestive of leiomyosarcoma.
• Hypercellularity.
• Nuclear atypia seen at low power.
• Few mitoses.

Variants

• Lipoleiomyoma - with adipose tissue.
  • Image: Lipoleiomyoma - low mag. (WC).
• Hypercellular leiomyoma - hypercellularity assoc. with more mutations.
• Atypical leiomyoma (AKA symplastic leiomyoma) - leiomyoma with nuclear atypia.
  • Image: Atypical leiomyoma (WC).

IHC

Work-up of suspicious leiomyomas:

• CD10 (+ve).
• Ki-67 (-ve).
• SMA (+ve).
• Desmin (+ve).

See also

• Leiomyosarcoma.
• Soft tissue lesions.