Leiomyosarcoma

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Leiomyosarcoma
Diagnosis in short

Leiomyosarcoma. H&E stain.

LM fasciclar arrangement (characteristic of smooth muscle), features of malignancy (usually need 2 of 3): † (1) nuclear atypia, (2) tumour cell necrosis, (3) mitoses - variable & definitions suffer from HPFitis
Subtypes major: spindled leiomyosarcoma (leiomyosarcoma NOS), epithelioid leiomyosarcoma, myxoid leiomyosarcoma; minor: leiomyosarcoma with prominent intravascular growth, leiomyosarcoma with osteoclast-type cells, leiomyosarcoma with clear cells, leiomyosarcoma with xanthoma-type cells
LM DDx pleomorphic undifferentiated sarcoma, atypical fibroxanthoma (skin only), EBV-associated smooth muscle tumour, carcinosarcoma, smooth muscle tumour of uncertain malignant potential (STUMP), endometrial stromal sarcoma, atypical leiomyoma (symplastic leiomyoma)
Gross "fleshy" appearance, necrosis, large size
Site uterus, skin, others

Syndromes hereditary leiomyomatosis and renal cell cancer

Prevalence uncommon
Prognosis poor

Leiomyosarcoma is a malignant tumour of smooth muscle. It is seen in various places including the uterus and skin.

General

  • Poor prognosis - usually.
    • In locally advanced/metastatic disease (arising from the uterus) the median survival is 12-14 months.[1]
  • Do not (generally) arise from leiomyomas.
  • Often singular, i.e. one tumour; unlike leiomyomas (which are often multiple).
  • May be a part of hereditary leiomyomatosis and renal cell cancer.

Note:

  • Skin leiomyosarcoma do so well it has been proposed to no longer refer to them as sarcomas.[2]

Gross

Features:

  • "Fleshy" appearance.
  • Necrosis.
  • Large size.
  • Often singular, i.e. one lesion; leiomyomata are often multiple.

Microscopic

Features:

  • Usually a cellular lesion.
  • Fasciclar arrangement:
    • Whorled look at low power.
    • Groups of spindle cells cut peripendicular to their long axis adjacent to groups of spindle cells cut in the plane of their long axis.
  • Features of malignancy (usually need 2 of 3): †
    1. Nuclear atypia.
    2. Tumour cell necrosis.
      • Should be patchy/multifocal.
        • Zonal necrosis is suggestive of vascular cause.
    3. Mitoses - key feature - definitions suffer from HPFitis:
      • >=10 mitoses/10 HPF - if spindled.[3]
      • >=5 mitoses/10 HPF - if epithelioid.[3]
      • >=2 mitoses/10 HPF - if myxoid.[3]
      • >=1 mitosis/10 HPF - if cutaneous.[2]
  • +/-Heterologous elements, e.g. malignant cartilage or bone.[4]

Notes:

  • † In deep soft tissue. 1 of 3 criteria is considered enough.[5]
  • Leiomyosarcoma de facto trumps other sarcomas.[4]
  • Mitotic rate seems to be a relatively weak predictor; modest rate may be malignant and a high rate benign.[6]

DDx:

Images

Uterine:

Cutaneous:

www:

Subtypes

Major variants:[7]

  • Spindled leiomyosarcoma (leiomyosarcoma NOS) - see above.
  • Epithelioid leiomyosarcoma.
  • Myxoid leiomyosarcoma.

Minor variants:[7]

  • Leiomyosarcoma with prominent intravascular growth.
  • Leiomyosarcoma with osteoclast-type cells.
  • Leiomyosarcoma with clear cells.
  • Leiomyosarcoma with xanthoma-type cells.

Epithelioid leiomyosarcoma

Features:[3]

  • >50% epithelial appearance.
  • >=5 mitoses/HPF - definition suffers from HPFitis.

Image:

Myxoid leiomyosarcoma

Features:[3]

  • >=2 mitoses/HPF - definition suffers from HPFitis.
  • May have minimal nuclear atypia.

IHC

Features:

  • Positive for SMC markers.
    • Desmin - present in all three types of muscle.
    • H-caldesmon.
    • Smooth muscle myosin.
  • CD10 -ve.

Others:[7]

  • ER, PR, AR +ve -- 30-40% of the time.
  • CD117 +ve/-ve.
  • p53 +ve.
  • MIB1 high.
  • Kertins usu. -ve -- more often +ve in epithelioid variant.

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SKIN LESION, LEFT SHOULDER (SUTURE AT 12 O'CLOCK), WIDE EXCISION:
- LEIOMYOSARCOMA, MARGINALLY EXCISED.
-- PLEASE SEE TUMOUR SUMMARY.
- DERMAL SCAR.

See also

References

  1. Hadoux, J.; Morice, P.; Lhommé, C.; Duvillard, P.; Balleyguier, C.; Haie-Meder, C.; Gouy, S.; Uzan, C. et al. (Sep 2013). "[Uterine leiomyosarcoma: epidemiology, pathology, biology, diagnosis, prognosis and treatment].". Bull Cancer 100 (9): 903-15. doi:10.1684/bdc.2013.1801. PMID 24004576.
  2. 2.0 2.1 Kraft S, Fletcher CD (April 2011). "Atypical intradermal smooth muscle neoplasms: clinicopathologic analysis of 84 cases and a reappraisal of cutaneous "leiomyosarcoma"". Am. J. Surg. Pathol. 35 (4): 599–607. doi:10.1097/PAS.0b013e31820e6093. PMID 21358302.
  3. 3.0 3.1 3.2 3.3 3.4 Nucci, Marisa R.; Oliva, Esther (2009). Gynecologic Pathology: A Volume in Foundations in Diagnostic Pathology Series (1st ed.). Churchill Livingstone. pp. 281. ISBN 978-0443069208.
  4. 4.0 4.1 Anh Tran, T.; Holloway, RW. (Sep 2012). "Metastatic leiomyosarcoma of the uterus with heterologous differentiation to malignant mesenchymoma.". Int J Gynecol Pathol 31 (5): 453-7. doi:10.1097/PGP.0b013e318246977d. PMID 22833086.
  5. URL: http://surgpathcriteria.stanford.edu/softsmoothmuscle/soft_tissue_leiomyosarcoma/differentialdiagnosis.html. Accessed on: 10 May 2013.
  6. Guo, L.; Liu, T.; Huang, H. (Oct 1996). "[Reappraisal of the pathological criteria for uterine leiomyosarcoma].". Zhonghua Bing Li Xue Za Zhi 25 (5): 266-9. PMID 9388868.
  7. 7.0 7.1 7.2 7.3 Nucci, Marisa R.; Oliva, Esther (2009). Gynecologic Pathology: A Volume in Foundations in Diagnostic Pathology Series (1st ed.). Churchill Livingstone. pp. 284. ISBN 978-0443069208.