Breast

Sarcoma

Other sarcomas



Last author update: 1 February 2017
Last staff update: 2 December 2022

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PubMed Search: Breast sarcomas

Emily S. Reisenbichler, M.D.
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Cite this page: Reisenbichler ES. Other sarcomas. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/breastmalignantRMS.html. Accessed February 8th, 2023.
Leiomyosarcoma
Definition / general
  • Malignant smooth muscle neoplasm of the breast

Essential features
  • Rare, < 1% of all breast malignancies
  • < 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

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

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 > 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., Mark R. Wick, M.D. and AFIP

Interesecting fascicles, pleomorphic nuclei and mitotic activity

Nuclear pleomorphism and mitotic activity

Dense cellularity and intersecting fascicles


Dermis involvement

Parenchyma

Desmin



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:

Spindle cell lipoma



Positive stains

Negative stains

Molecular / cytogenetics description

Differential diagnosis
Low grade myofibroblastic sarcoma
Definition / general
  • Spindle cell sarcoma with myofibroblastic differentiation
  • Also called myofibrosarcoma

Essential features
  • Uncommon tumor overall, occurring predominantly in the head and neck or extremities with only rare reports within the breast
  • At least moderate cytologic atypia must be seen focally
  • Not part of WHO breast classification

Prognostic factors
  • Frequently recurs, particularly when incompletely excised
  • Low rates of metastasis but lung is most common site when it occurs (Am J Surg Pathol 2001;25:219)

Case reports

Treatment

Gross description
  • Well circumscribed tumor with firm, pale cut surface, despite infiltrative microscopic growth

Microscopic (histologic) description
  • Spindle cells in a fascicular or storiform growth pattern
  • Variable stromal collagen
  • Cells demonstrate pale eosinophilic cytoplasm and the nuclei must show at least moderate atypia focally and hyperchromasia
  • Diffusely infiltrative borders

Microscopic (histologic) images

Contributed by Mark R. Wick, M.D.

Low grade myofibroblastic sarcoma



Positive stains

Negative stains

Electron microscopy description
  • Prominent rough endoplasmic reticulum, peripheral myofilaments and the fibronectin fibrils of the fibronexus junctions (J Clin Pathol 2009;62:236)

Molecular / cytogenetics description
  • Gains at 1p11 → p36.3 (66%), 12p12.2 → p13.2 (45%), 5p13.2 → p15.3 (31%), +22 (28%), loss at 15q25 → q26.2 (24%) (Am J Clin Pathol 2009;131:701)
  • Complex DNA copy number changes
  • Higher average number of chromosomal aberrations than seen in nodular fasciitis

Differential diagnosis
Osteosarcoma
Definition / general
  • Malignant osteoid producing neoplasm

Essential features
  • Exceedingly rare tumor in the breast with < 150 reported cases in the literature
  • Comprised of cytologically malignant cells with osteoid production, lacking morphologic or immunohistochemical evidence of an epithelial / carcinomatous component
  • Must extensively sample tumors to exclude diagnoses of malignant phyllodes with osteosarcomatous differentiation and metaplastic carcinoma with osteogenic matrix production
  • Some experts believe that most, if not all, reported osteosarcomas of the breast actually represent matrix producing carcinomas (Breast 2013;22:13)

Etiology

Clinical features
  • Typically presents in the fifth or sixth decade of life
  • Large, palpable mass

Radiology description
  • Irregular hyperdense mass by mammography
  • Hypoechoic mass by ultrasound

Prognostic factors

Case reports

Treatment
  • Complete resection with negative margins
  • Routine axillary lymph node dissection not necessary due to tendency to metastasize to lungs rather than regional lymph nodes
  • Utility of adjuvant radiation or chemotherapy is unclear due to rarity of this tumor type in this location

Gross description
  • Well circumscribed large tumor with firm to gritty cut surface
  • Difficulty in sectioning possible if abundant osteoid production present

Gross images

Contributed by Nitin Marwaha, M.D.
Missing Image

Well circumscribed, bony hard mass



Microscopic (histologic) description
  • Spindle to epithelioid cells with nuclear atypia, hyperchromasia and mitotic activity, including atypical forms
  • Lace-like osteoid production
  • Absence of an in situ carcinoma component

Microscopic (histologic) images

Contributed by Emily S. Reisenbichler, M.D. and Nitin Marwaha, M.D.

Osteosarcoma, 40x magnification

Osteosarcoma, 60x magnification

Missing Image Missing Image Missing Image Missing Image

45 year old woman with right breast mass



Positive stains

Negative stains
  • Cytokeratins (typically high molecular weight keratins such as CK5 / 6) and myoepithelial markers (such as p63): to rule out a metaplastic carcinoma

Differential diagnosis
Rhabdomyosarcoma
Definition / general
  • Malignant neoplasm with skeletal muscle differentiation

Essential features
  • Comprises < 3% of all adult primary soft tissue sarcomas and exceedingly rare as a primary breast tumor
  • Primary rhabdomyosarcoma of the breast is most commonly alveolar subtype and is seen more frequently in the pediatric / adolescent population (Med Pediatr Oncol 1997;29:181)
  • Typically composed of small, round to spindled cells, with eosinophilic cytoplasm, some of which show cytoplasmic cross striations (embryonal and alveolar subtypes); larger cells with greater degree of atypia seen in pleomorphic subtype
  • Must exclude other tumor types with heterologous rhabdomyosarcomatous differentiation (such as malignant phyllodes)

Clinical features
  • Primary rhabdomyosarcoma of the breast is seen most frequently in the pediatric / adolescent population and therefore is not typically identified by routine screening mammography
  • Presents as a palpable, circumscribed, rapidly growing mass
  • Presentation as a metastasis from a primary rhabdomyosarcoma elsewhere in the body occurs in 3 - 6% cases and portends a very poor prognosis (J Pediatr Hematol Oncol 2017;39:62)

Radiology description
  • Due to the breast density of the pediatric and adolescent population, ultrasound is the imaging modality of choice for radiographic characterization of this tumor type (Eur J Radiol 2003;48:282)
  • Hypoechoic, round or lobulated nodule / mass by ultrasound

Prognostic factors
  • Patients with primary breast alveolar rhabdomyosarcoma have a poor prognosis, frequently dying of disease with disseminated metastases (J Pediatr Hematol Oncol 2017;39:62)
  • Embryonal subtype portends much better prognosis than alveolar or pleomorphic subtypes

Case reports

Treatment
  • As with all primary breast sarcomas, wide excision without axillary dissection is the mainstay of treatment
  • Adjuvant or neoadjuvant radiation often used in large or incompletely resected tumors
  • Utility of chemotherapy is unclear due to the rarity of this tumor type

Clinical images

Contributed by Mark R. Wick, M.D.

Alveolar



Gross description
  • Circumscribed, nonencapusulated mass

Gross images

Images hosted on other servers:

Large fungating mass involving right breast

Large firm lobulated tumor



Microscopic (histologic) description
  • 3 microscopic subtypes:
    • Alveolar: sheets of small, round cells clustered with variable amounts of fibrous septa; may contain scattered giant cells
    • Embryonal: cytologically round to spindle cells with scant cytoplasm in a myxoid background; elongated cells with more abundant eosinophic cytoplasm referred to as strap cells or tadpole cells
    • Pleomorphic: sheets of large cells demonstrating marked nuclear atypia or "anaplasia" with eosinophilic cytoplasm

Microscopic (histologic) images

Contributed by Mark R. Wick, M.D.

Alveolar

Alveolar with differentiation

Embryonal



Cytology images

Contributed by Mark R. Wick, M.D.

Embryonal, FNAB



Positive stains

Negative stains

Electron microscopy description
  • Skeletal differentiation, as evidenced by ultrastructural specific myofilament arrays, focal density, Z band material and pinocytotic vesicle, is suggestive of rhabdomyosarcomatous differentiation but is not specific for the diagnosis of rhabdomyosarcoma (J Pathol Transl Med 2015;49:93)
  • Features may not be evident in solid variants of the alveolar subtype

Molecular / cytogenetics description
  • Alveolar: t(2;13)(q35;q4), PAX3::FOXO1 fusion more frequent than t(1;13)(p36;q14), PAX7::POXO1 fusion
  • Embryonal: chromosome loss, deletion or uniparental disomy resulting in loss of chromosome 11 loci
  • Pleomorphic: complex karyotype

Differential diagnosis
Stromal sarcoma
Definition / general
  • The 4th WHO edition (2012) reclassified this periductal stromal tumor as the preferred neutral term in the family of fibroepithelial tumor
  • Stromal proliferation around open, benign tubules

Essential features
  • Considered a type of fibroepithelial tumor lesion with stromal proliferation around benign tubules
  • Lacks the defined tumor borders and compressed tubules of fibroadenoma and leaf-like architecture of phyllodes tumor
  • Must demonstrate stromal atypia and mitotic activity to be considered a sarcoma

Clinical features
  • Occurs in peri and postmenopausal women (median 55.3 years), ~10 years older than the median phyllodes presentation (Am J Surg Pathol 2003;27:343)
  • Variable clinical presentation

Prognostic factors

Case reports

Treatment
  • Given the likely relationship to fibroepithelial lesions, treatment is similar to that of phyllodes tumor
  • Wide excision with negative margins
  • As with primary breast sarcoma, assessment of axillary sentinel lymph nodes is not necessary
  • Adjuvant chemotherapy and radiation are not typically warranted unless presenting with a higher grade sarcomatous component

Clinical images

Contributed by Mark R. Wick, M.D.

Mammogram



Gross description
  • Ill defined nodular mass (mean 3 cm)

Microscopic (histologic) description
  • Increased stromal cellularity of spindled stroma surrounding or cuffing benign ducts in a pericanalicular pattern
  • Involved tubules and ducts are not malignant
  • Stromal cells demonstrate at least moderate cytologic atypia and mitotic activity
  • Infiltrative and often multinodular microscopic border
  • May be seen with areas of angiosarcomatous or liposarcomatous components (Am J Surg Pathol 2003;27:343, Int J Surg Pathol 2015;23:221)

Microscopic (histologic) images

Contributed by Emily S. Reisenbichler, M.D. and Mark R. Wick, M.D.

Cytologically atypical spindled cells cuffing benign ducts

Numerous mitoses present in
cytologically atypical stromal
cells adjacent to ducts

Various images



Positive stains
  • CD34 (mostcases), CD117 (approximately ¼ of cases), HHF35 (< 10% of cases)

Negative stains

Electron microscopy description
  • Undifferentiated mesenchymal cell features such as free ribosomes and irregular profiles of rough endoplasmic reticulum
  • Fibroblastic differentiation such as well organized dilated rough endoplasmic reticulum, Golgi complexes, cytoplasmic filaments and pericellular collagen (Cancer 1979;43:209)

Differential diagnosis
  • Periductal stromal hyperplasia:
    • Nodular growth, lacks the cytologic atypia and mitoses typical of a stromal sarcoma (0 - 2 mitoses per 10 high power fields)
  • Phyllodes tumor:
    • Has a more defined tumor border with compression and distortion of ductal elements causing a leaf-like architecture
    • Abundant stromal overgrowth of intralobular stroma, not limited only to periductal areas
Undifferentiated pleomorphic sarcoma
Definition / general
  • See also Soft tissue topic
  • A malignant tumor showing no line of differentiation
  • Not part of the WHO classification of breast tumors
  • Previously known as malignant fibrous histiocytoma (MFH)

Essential features
  • High grade sarcoma with no distinctive microscopic, immunohistochemical or molecular features fitting any specific line of differentiation
  • Diagnosis of exclusion
  • Undifferentiated sarcomas account for ~20% of soft tissue sarcomas in other parts of the body but are exceedingly rare in the breast

Etiology
  • May occur as a primary / de novo tumor or in the postradiation setting

Clinical features
  • Most occur in fifth to sixth decade of life
  • Majority present as rapidly enlarging palpable mass but can be incidental finding at screening

Diagnosis
  • A limited core biopsy may underestimate tumor grade as grading systems such as the 3 tier French (FNCLCC) system are dependent on percentage necrosis and mitotic rate

Radiology description

Prognostic factors
  • Close / involved margins, large tumor size (> 5 cm) and high grade histology typically indicate a worse prognosis

Case reports

Treatment
  • Surgical resection with a negative margin (R0) is standard treatment
  • Sentinel lymph node biopsy is not warranted
  • Adjuvant radiation is often utilized in large tumors or following incomplete (R1 / R2) surgical resections
  • Response to adjuvant chemotherapy is typically low but may be used in patients with large, unresectable or metastatic tumors

Clinical images

Images hosted on other servers:

Cystic tumor with skin tethering



Gross images

Images hosted on other servers:

Tumor invades skin

Specimen includes ribs posteriorly



Microscopic (histologic) description
  • Cell morphology may be spindle, round / epithelioid or pleomorphic, demonstrating marked cytologic atypia
  • Often high mitotic activity
  • May be associated with multinucleated giant cells or an inflammatory background

Microscopic (histologic) images

Contributed by Emily S. Reisenbichler, M.D. and Mark R. Wick M.D.
Missing Image

Spindle and epithelioid cells

Pleomorphic cells

Various images



Cytology description
  • Single or clustered spindled cells with nuclear pleomorphism
  • Absence of an epithelial component

Positive stains

Negative stains
  • Typically negative for most markers

Molecular / cytogenetics description
  • Complex karyotypes without specific recurrent aberrations

Differential diagnosis
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