Breast
Sarcoma
Leiomyosarcoma
Author: Emily S. Reisenbichler, M.D.
Topic Completed: 1 July 2016
Minor changes: 19 March 2021
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Leiomyosarcoma [title] breast
Table of Contents
Definition / general | Essential features | Etiology | Clinical features | Radiology description | Prognostic factors | Case reports | Treatment | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Cytology images | Positive stains | Negative stains | Molecular / cytogenetics description | Differential diagnosisCite this page: Reisenbichler ES. Leiomyosarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/breastmalignantLMS.html. Accessed October 15th, 2021.
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
Etiology
- 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
- Occur most frequently in the 4th and 7th decades of life, typically in post-menopausal women (Case Rep Pathol 2012;2012:491984)
- Average size of 5 cm
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
- 18 year old woman with leiomyosarcoma invading the breast skin (Breast 2011;20:389)
- 19 year old woman with primary leiomyosarcoma clicinally suspected to be fibroadenoma (Case Rep Pathol 2012;2012:491984)
- 51 year old woman with primary breast leiomyosarcoma located in the premammary zone / subcutaneous fat (Clin Imaging 2015;39:1105)
- 59 year old woman with leiomyosarcoma arising in irradiated region after breast conserving surgery (Surg Case Rep 2015;1:76)
Treatment
- 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
Parenchyma
Desmin
Images hosted on other servers:
Cellular pleomorphic tumor
Nipple areola complex
Densely cellular tumor
Cigar shaped nuclei
SMA+
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
Molecular / cytogenetics description
- Loses of 16q and 1p (Oncogene 2010;29:845)
Differential diagnosis
- Leiomyosarcomatous differentiation in a malignant phyllodes tumor
- Metaplastic (spindle cell) carcinoma
- Myofibroblastoma
