Soft tissue

Extraskeletal bone tumors

Mesenchymal chondrosarcoma


Editorial Board Members: Jose G. Mantilla, M.D., Borislav A. Alexiev, M.D.
Iva Brčić, M.D., Ph.D.
Bernadette Liegl-Atzwanger, M.D.

Topic Completed: 14 July 2021

Minor changes: 14 July 2021

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PubMed Search: Mesenchymal chondrosarcoma [TI] free full text[sb] pathology

Iva Brčić, M.D., Ph.D.
Bernadette Liegl-Atzwanger, M.D.
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Cite this page: Brčić I, Liegl-Atzwanger B. Mesenchymal chondrosarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissueeskchondrosarcomamesenchymal.html. Accessed September 20th, 2021.
Definition / general
  • Malignant biphasic mesenchymal neoplasm with a well differentiated hyaline cartilage component
  • Most cases have HEY-NCOA2 fusions; however IRF2BP2-CDX1 fusion has also been described (PLoS One 2012;7:e49705)
Essential features
  • Malignant biphasic neoplasm that most commonly involves soft tissue, bone and intracranial sites, with tendency for late local recurrences and distant metastases
ICD coding
  • ICD-O: 9240/3 - mesenchymal chondrosarcoma
  • ICD-10:
    • C40 - malignant neoplasm of bone and articular cartilage of limbs
    • C41 - malignant neoplasm of bone and articular cartilage of other and unspecified sites
  • ICD-11: 2B50.Z & XH8X47 - chondrosarcoma of bone and articular cartilage of unspecified sites and mesenchymal chondrosarcoma
Epidemiology
  • Usually adolescents and young adults
  • Slight female predominance
Sites
  • Most commonly bone, soft tissue (head and neck, thigh), intracranial sites (meninges) and visceral organs
  • Bone lesion: up to 50% in jaw (Arch Pathol Lab Med 2012;136:61)
Pathophysiology
  • Gene fusion driven
Etiology
  • HEY1-NCOA2 fusion evokes many different mechanisms, including direct DNA binding, protein - protein interaction and epigenetic modification
  • Combination of these pathway dysregulations (including Notch signaling pathway, chromatin remodeling, apoptosis and transforming growth factor beta [TGFβ] signaling) results in a chimeric fusion protein that drives the biology of mesenchymal chondrosarcoma (Curr Oncol Rep 2018;20:37)
Clinical features
  • Clinical symptoms depend on the tumor location and can last for years prior to diagnosis
  • Enlarging, usually painful mass
  • Neurologic symptoms If arising in spine / cranium (Arch Pathol Lab Med 2012;136:61)
Diagnosis
  • Diagnostic diagram includes radiology, histology (biopsy, resection specimen) with immunohistochemistry and molecular analysis
Radiology description
  • CT scan:
    • Lobulated, destructive lytic lesion with granular, ring and arc or irregularly shaped calcifications (Radiology 1993;186:819, Skeletal Radiol 2005;34:785)
    • Bone lesion: usually erodes / destroys the cortex and involves the surrounding soft tissue
  • MRI:
    • Lobulated, heterogeneous lesion with low signal intensity on T1 weighted images and high signal intensity on T2 (Skeletal Radiol 2005;34:785)
Radiology images

Contributed by Borislav A. Alexiev, M.D.
Anterior mediastinal mass

Anterior mediastinal mass

Prognostic factors
  • In one study, 5, 10 and 20 year overall survival was 55.0%, 43.5% and 15.7%, respectively (PLoS One 2015;10:e0122216)
  • With chemotherapy: 5 year and 10 year overall survival is 84% and 80%, respectively
  • Without chemotherapy, under surveillance: 5 year and 10 year overall survival is 73% and 46%, respectively (Eur J Cancer 2015;51:374)
Case reports
Treatment
Gross description
  • Lobulated, solid, firm, gray-tan, fleshy mass with scattered gritty white calcifications
  • Bone lesions arise in the medullary cavity or on the bone surface, causing cortical destruction and extension into the soft tissue (Arch Pathol Lab Med 2012;136:61)
Gross images

Contributed by Iva Brčić, M.D., Ph.D. and Bernadette Liegl-Atzwanger, M.D.
Lobulated mass

Lobulated mass

Calcifications

Calcifications

Frozen section description
  • Tumor composed of islands of well differentiated hyaline cartilage and primitive mesenchymal cells / undifferentiated small blue cells
Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Iva Brčić, M.D., Ph.D. and Bernadette Liegl-Atzwanger, M.D.
Biphasic tumor

Biphasic tumor

Abrupt transition

Abrupt transition

2 components

2 components

Spindle cell morphology

Spindle cell morphology

Transition higher power

Transition higher power

Cellular atypia

Cellular atypia


CD99 staining

CD99 staining

Cytology description
  • Highly cellular smears composed of small round blue cells with high nuclear to cytoplasmic ratio infiltrating the fibrillary matrix (Arch Pathol Lab Med 2018;142:1421)
Positive stains
Molecular / cytogenetics description
Sample pathology report
  • Right thigh, excision:
    • Extraskeletal mesenchymal chondrosarcoma (see comment)
    • Comment: Tumor is composed of islands of well differentiated hyaline cartilage and primitive mesenchymal cells. Immunohistochemically, the tumor cells are positive for S100, focally positive for CD99 and SOX9 and are negative for CD20 and keratin. The morphology and immunoprofile strongly support the diagnosis of mesenchymal chondrosarcoma.
Differential diagnosis
  • Other small round cell neoplasms:
  • Ewing sarcoma:
    • Tumor composed of monotonous round blue cells
    • No hemangiopericytoma-like vascular pattern or cartilaginous component
    • NKX2.2+, CD99 diffuse membranous staining
    • Harbors EWSR1 negative and FUS rearrangements
  • Lymphoma:
    • Lack of cartilaginous component; lymphoid antibodies positive
  • Rhabdomyosarcoma:
  • Synovial sarcoma:
    • No cartilaginous component
    • Keratin+, EMA+, TLE1+, SSX+, SS18-SSX+
    • Harbors SSX rearrangements
  • Malignant solitary fibrous tumor:
    • No cartilaginous component, hemangiopericytoma-like vascular pattern present
    • CD34+, STAT6+
    • Harbors NAB2-STAT6 fusion
Board review style question #1
Which of the following is true about mesenchymal chondrosarcoma?

  1. Cut surface is white with myxoid areas
  2. Cytology smears are paucicellular
  3. On imaging, calcifications are rare
  4. Tumor cells are typically negative for S100
  5. Tumor is composed of undifferentiated small blue cells mixed with islands of mature appearing, well differentiated hyaline cartilage
Board review style answer #1
E. Tumor is composed of undifferentiated small blue cells mixed with islands of mature appearing, well differentiated hyaline cartilage

Comment Here

Reference: Mesenchymal chondrosarcoma
Board review style question #2

A 24 year old man presented with an intracranial mass arising from the meninges. Histologically, tumor is composed of areas with small blue cells and islands of well differentiated hyaline cartilage. Which of the following is most likely the correct diagnosis?

  1. B cell lymphoma
  2. Ewing sarcoma
  3. Mesenchymal chondrosarcoma
  4. Rhabdomyosarcoma
  5. Synovial sarcoma
Board review style answer #2
C. Mesenchymal chondrosarcoma

Comment Here

Reference: Mesenchymal chondrosarcoma
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