Last author update: 1 July 2016
Last staff update: 16 December 2021

Copyright: 2002-2022,, Inc.

PubMed Search: Leiomyosarcoma [title] breast

Emily S. Reisenbichler, M.D.
Page views in 2021: 1,106
Page views in 2022 to date: 641
Cite this page: Reisenbichler ES. Leiomyosarcoma. website. Accessed July 5th, 2022.
Definition / general
  • Malignant smooth muscle neoplasm of the breast
Essential features
  • Rare, < 1% of all breast malignancies
  • Less than 50 primary leiomyosarcomas of the breast reported in the literature
  • Should be distinguished from metastatic tumor
  • Primary tumors likely arise from smooth muscle of the nipple or vascular wall
  • Have been reported to occur secondary to radiation (Surg Case Rep 2015;1:76)
Clinical features
Radiology description
  • Mammographically presents as a mass or architectural distortion
  • By ultrasound, lesions are homogenously hypoechoic, lobular or oval with microlobulated or indistinct margins (Acta Radiol 2011;52:597)
Prognostic factors
  • Type of surgery does not affect prognosis as long as the tumor is excised with an adequate (2 - 3 cm) margin (Breast 2011;20:389)
  • Due to the rare nature of this tumor, no specific prognostic features are established in primary leiomyosarcoma arising in the breast
  • If the tumor is cutaneous and limited to the dermis of the breast skin (i.e. atypical intradermal smooth muscle neoplasm), rather than arising in the mammary parenchyma, prognosis is excellent without metastases
Case reports
  • As no axillary lymph node metastases have been reported with primary breast leiomyosarcoma, sentinel lymph node excision is not indicated (Breast 2011;20:389)
  • Wide excision with at least 2 cm margin, but 3 cm margin is recommended (Breast 2011;20:389)
  • In tumors larger than 3 cm, or with inadequate excision, radiotherapy may be indicated
  • Adjuvant chemotherapy may result in greater clinical response in radiation induced sarcomas (Surg Case Rep 2015;1:76)
Gross images

Images hosted on other servers:

Lobulated elastic tumor

Microscopic (histologic) description
  • Intersecting fascicle of spindled cells with abundant eosinophilic cytoplasm and cigar shaped nuclei demonstrating variable pleomorphism, mitotic activity and necrosis
  • Tumor borders are typically infiltrative
Microscopic (histologic) images

Contributed by Emily S. Reisenbichler, M.D.

Interesecting fascicles, pleomorphic nuclei and mitotic activity

AFIP images

Nuclear pleomorphism and mitotic activity

Dense cellularity and intersecting fascicles

Contributed by Dr. Mark R. Wick

Dermis involvement



Images hosted on other servers:

Cellular pleomorphic tumor

Nipple areola complex

Densely cellular tumor

Cigar shaped nuclei


Alpha smooth muscle actin

Cytology description
  • Large, dissociated round to spindle cells, medium to large, with abundant vacuolated cytoplasm with occasional intranuclear cytoplasmic invaginations
  • Mitotic activity, including abnormal forms, nuclear atypia and a necrotic background favor a malignant process
  • Immunohistochemistry is typically required to distinguish leiomyosarcoma from other malignant spindle cell tumors of the breast (Diagn Pathol 2006;1:13)
Cytology images

Images hosted on other servers:

Various images

Positive stains
Negative stains
Molecular / cytogenetics description
Differential diagnosis
Back to top
Image 01 Image 02