Lung tumor
Mesenchymal
Primary pulmonary myxoid sarcoma
Copyright: 2019, PathologyOutlines.com, Inc.
PubMed Search: Primary pulmonary myxoid sarcoma full text[sb]
Mesenchymal
Primary pulmonary myxoid sarcoma
Editor-in-Chief: Debra Zynger, M.D.
Topic Completed: 6 June 2019
Minor changes: 27 December 2019
Copyright: 2019, PathologyOutlines.com, Inc.
PubMed Search: Primary pulmonary myxoid sarcoma full text[sb]
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Diagnosis | Radiology description | Radiology images | Prognostic factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Electron microscopy description | Molecular / cytogenetics description | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review answer #1 | Board review style question #2 | Board review answer #2Cite this page: Gui H, Zhang PJL. Primary pulmonary myxoid sarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungtumorprimpulmmyxsarcoma.html. Accessed May 27th, 2020.
Definition / general
- Low grade tumor
- Typically in or close to large airways
- Lobulated tumor with spindle and stellate cells arranged in lace-like strands and cords within prominent myxoid stroma
Essential features
- Endobronchial nodular mass with reticular / lace-like growth pattern and abundant myxoid stroma
- Expresses EMA and vimentin, negative for most other markers
- FISH positive for EWSR1 rearrangement (85%)
Terminology
- Low grade malignant myxoid endobronchial tumor
ICD coding
Epidemiology
- Mean age = 46.3 years; F:M = 1.4:1 (24 cases)
- 40% with cough, hemoptysis, chest pain; 20% present as incidental lung mass (Am J Surg Pathol 2011;35:1722)
Sites
- Bilateral lungs, 76% within or close to a large bronchus (Int J Surg Pathol 2017;25:518)
Pathophysiology
- Probably originates from primitive mesenchymal cells with myofibroblastic or fibroblastic differentiation (Virchows Arch 2014;465:453)
- Controversial relationship to myxoid angiomatoid fibrous histiocytoma with similar EWSR1 fusion genes (Histopathology 2014;65:144)
Etiology
- Smoking history in 80% (Am J Surg Pathol 2011;35:1722)
Diagnosis
- Relies on histology, immunohistochemistry and FISH in biopsy or surgical resection
Radiology description
- Mass related to bronchus, predominantly endobronchial
Radiology images
Contributed by Hongxing (Simon) Gui, M.D., Ph.D.
Endobronchial mass
Prognostic factors
- Patients with EWSR1 rearrangement have favorable prognosis; wild type EWSR1 portends poor clinical outcome (Pol J Pathol 2017;68:261)
Case reports
- 29 year old woman with mass in a major fissure of the left lung without parenchymal invasion (Thorac Cancer 2017;8:535)
- 32 year old woman with tumor adjacent to the main bronchus (Pathology 2017;49:792)
- 48 year old man with a huge mass extending into the right main bronchus (Pol J Pathol 2017;68:261)
- 80 year old woman with an endobronchial mass in the left main bronchus (Int J Surg Pathol 2017;25:518)
- 3 cases with features overlapping with angiomatoid fibrous histiocytoma (Histopathology 2014;65:144)
Treatment
- Surgical resection (Am J Surg Pathol 2011;35:1722)
Gross description
- Generally, < 4 cm, well circumscribed or nodular
- Glistening or gelatinous cut surface, white-gray to yellow (Am J Surg Pathol 2011;35:1722)
Microscopic (histologic) description
- Lobulated architecture, reticular or lace-like pattern with anastomosing cords and strands, abundant myxoid stroma, often lightly basophilic (Am J Surg Pathol 2011;35:1722)
- Oval, spindle to polygonal cells with minimal to moderate atypia, infrequent mitotic figures with the majority < 5/10 high power fields
- Admixed lymphoplasmacytic infiltrate
Microscopic (histologic) images
Contributed by Hongxing (Simon) Gui, M.D., Ph.D.
Nodular mass
Reticular pattern
Multinodular growth
Spindle cells
Positive stains
- Vimentin, EMA, CD99 (weak focal) (Pol J Pathol 2017;68:261)
- Stroma is positive for Alcian blue stain, which is sensitive to hyaluronidase treatment (Am J Surg Pathol 2011;35:1722)
Negative stains
- S100, cytokeratin, p63, CD34, CD31, actin - alpha smooth muscle, actin - muscle specific, desmin (rarely positive), TTF1, calretinin
Electron microscopy description
- Focal dense plaques present in the plasma membrane, external lamina and intermediate junctions are rarely observed (Virchows Arch 2014;465:453)
Molecular / cytogenetics description
- ~85% tumors showed t(2;22)(q33;q12) with EWSR1-CREB1 fusion gene detected by FISH or PCR (Int J Surg Pathol 2017;25:518)
Sample pathology report
- Lung, right lower lobe, lobectomy:
- Primary pulmonary myxoid sarcoma (see comment)
- Comment: H&E sections demonstrate a well circumscribed endobronchial tumor composed of lobules of spindled and stellate cells arranged in a reticular pattern within a myxoid background. A chronic inflammatory infiltrate is seen throughout the tumor. Immunohistochemically, the tumor cells are positive for EMA and negative for AE1 / AE3, CAM5.2, pancytokeratin, p40, desmin, actin - alpha smooth muscle, CD34, TTF1, c-kit, vimentin, CD1a and S100. A FISH test for EWSR1 was positive for rearrangement in the tumor cells. The morphology in combination with the FISH test result confirm the above diagnosis.
Differential diagnosis
- Extraskeletal myxoid chondrosarcoma:
- History of soft tissue primary, rarely arising intrathoracic as a primary
- S100+
- FISH positive for EWSR1-NR4A3 fusion or others
- Myxoid angiomatoid fibrous histiocytoma:
- Peripheral lymphoid cuff
- Whorled or storiform growth patterns common
- 50% desmin+
- FISH positive for EWSR1-ATF1 (more common), EWSR1-CREB1 and FUS-ATF1
- Inflammatory myofibroblastic tumor:
- Positive for actin - alpha smooth muscle, desmin and ALK
- Myoepithelioma:
- Clear and plasmacytoid cells
- Positive for myoepithelial markers (cytokeratins, p63, S100, calponin and actin - alpha smooth muscle)
Board review style question #1
Which of the following is a good prognostic factor for this primary pulmonary lung lesion?
Primary pulmonary lung lesion
- Brisk lymphoplasmacytic infiltrate
- FISH positive for EWSR1 translocation
- Lack of tumor necrosis
- Middle age onset
- Size > 5 cm
Board review answer #1
B. Primary pulmonary myxoid sarcoma tumors (shown in photo) with EWSR1 rearrangement have a relatively good prognosis
Reference: Primary pulmonary myxoid sarcoma
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Reference: Primary pulmonary myxoid sarcoma
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Board review style question #2
Which of the following entities is the closest mimicker of primary pulmonary myxoid sarcoma?
- Epithelioid hemangioendothelioma
- Extraskeletal myxoid chondrosarcoma
- Inflammatory myofibroblastic tumor
- Myoepithelioma
- Myxoid angiomatoid fibrous histiocytoma
Board review answer #2
E. Myxoid angiomatoid fibrous histiocytoma and primary pulmonary myxoid sarcoma have many overlapping features
Reference: Primary pulmonary myxoid sarcoma
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Reference: Primary pulmonary myxoid sarcoma
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