A 19-year-old female patient presented with a circumscribed palpable mass lesion thought to be a fibroadenoma based on clinical exam and imaging. Needle biopsy showed an undifferentiated malignancy.

Section shows a high-grade spindle cell neoplasm with pushing borders image, compressing adjacent breast tissue image. Further work-up showed this tumor to be a rhabdomyosarcoma. Staging studies were negative.



  • Malignant mesenchymal neoplasm derived from connective tissue elements of the breast

    • Sarcomas of the breast are rare

    • Sarcomatous-appearing tumors more likely to be metaplastic carcinoma or malignant phyllodes

    • Mammary sarcoma should be diagnosis of exclusion

  • Sarcoma involving breast tissue can be broadly divided into 3 categories

    • Idiopathic (de novo) sporadic cases (primary)

    • Post therapy (secondary)

    • Metastatic

  • Any sarcoma that occurs elsewhere can occur in the beast as a primary tumor

    • Angiosarcoma is most common primary sarcoma followed by liposarcoma


Environmental Exposure

  • Etiology of most soft tissue sarcomas remains unknown

  • Primary mammary sarcoma of the breast can be de novo or secondary to prior treatment for carcinoma

    • Sporadic sarcomas tend to occur in younger age group

    • Sarcomas associated with prior use of breast external beam radiation therapy

      • Most common: Angiosarcoma, malignant fibrous histiocytoma, fibrosarcoma

    • Sarcomas association with chronic lymphedema that occurs after surgery with or without radiation treatment

      • Stewart-Treves syndrome

      • Lymphedema-associated lymphangiosarcoma



  • Incidence

    • Mammary sarcomas: < 0.1% of breast malignancies

      • Primary sarcomas (other than angiosarcoma) are exceedingly rare

      • Annual incidence of breast sarcomas: 4.6 cases per 1,000,000 women


  • Most common presentation: Palpable mass

    • Often rapidly enlarging

Natural History

  • Based on histologic type of tumor, grade, and stage at presentation

  • May show aggressive behavior with high likelihood for local/systemic recurrence

    • Hematogenous dissemination

      • Metastases to lungs, bone marrow, and liver are most common

      • Metastases to axillary lymph node are exceedingly rare


  • Surgical approaches

    • Surgical excision with clean margins

      • Total mastectomy is most common

      • Smaller lesion may be treated with breast-conserving therapy

    • Axillary dissection is not indicated given the rarity of lymph node involvement

  • Adjuvant therapy

    • Any role for adjuvant chemotherapy &&/or radiation therapy is unclear


  • Primary mammary sarcomas have prognosis similar to that of their soft tissue counterparts

    • Based on histologic type, grade, and stage of tumor

  • Tumor size is significantly associated with overall survival (risk ratio = 1.3 per 1 cm increase)

  • Tumor grade is prognostically significant in some but not all reports

Post-Irradiation Sarcoma

  • Radiation therapy (RT) is important in adjuvant treatment of breast cancer

    • Complications include development of post-irradiation malignancy

  • Criteria for defining a post-irradiation sarcoma

    • Histological confirmation of sarcoma

    • Prior history of RT

      • Latency periods of several years until development of sarcoma

      • Development of sarcoma within previously irradiated field

    • Risk for development of post-irradiation sarcoma

      • 0.03-0.8% with long-term follow-up (15 years)


Mammographic Findings

  • Lobulated or ill-defined mass

    • Architectural distortion

Ultrasonographic Findings

  • Circumscribed or spiculated mass

    • Ultrasound is generally better for delineating size of lesion



  • Superficial lesions tend to be smaller than those located deep in the breast

    • Larger lesions may show areas of hemorrhage and necrosis

  • Mean: 5.7 cm (range: 0.3-12.0 cm)


Histologic Features

Jul 6, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Sarcomas

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