Leiomyoma

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A leiomyoma is a very common benign tumour of smooth muscle. Leiomyomas fit into the soft tissue group of lesions. They are extremely common in the uterus. They may also be seen in the skin.

General

  • Benign.

Cutaneous leiomyomas

  • May be part of Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC).[1][2]

Uterine leiomyomas

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

Gross

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

Factors 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.

Uncommon present - see note:

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

Note:

  • Leiomyosarcoma is diagnosed if all of the following are present: (1) high mitotic rate (dependent on site), (2) marked nuclear atypia (seen at low power), (3) necrosis.

Variants

  • Lipoleiomyoma - with adipose tissue.
  • Hypercellular leiomyoma - hypercellularity assoc. with more mutations.[3]
  • Atypical leiomyoma (AKA symplastic leiomyoma) - leiomyoma with nuclear atypia.
  • Benign metastasizing leiomyoma.[4]
    • This is just what it sounds like. Some believe these are low grade leiomyosarcomas

IHC

Work-up of suspicious leiomyomas:[5]

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

See also

References

  1. URL: http://www.ncbi.nlm.nih.gov/books/NBK1252/. Accessed on: 2 September 2011.
  2. URL: http://ccr.cancer.gov/staff/gallery.asp?profileid=12822. Accessed on: 2 September 2011.
  3. http://www3.interscience.wiley.com/journal/119360394/abstract
  4. Patton, KT.; Cheng, L.; Papavero, V.; Blum, MG.; Yeldandi, AV.; Adley, BP.; Luan, C.; Diaz, LK. et al. (Jan 2006). "Benign metastasizing leiomyoma: clonality, telomere length and clinicopathologic analysis.". Mod Pathol 19 (1): 130-40. doi:10.1038/modpathol.3800504. PMID 16357844. http://www.nature.com/modpathol/journal/v19/n1/full/3800504a.html.
  5. STC. 25 February 2009.