Nasal cavity, paranasal sinuses, nasopharynx

Other malignant tumors

Biphenotypic sinonasal sarcoma

Editorial Board Member: Bin Xu, M.D., Ph.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Josephine K. Dermawan, M.D., Ph.D.
Laura O. Rabinowitz, M.D.

Last author update: 24 April 2020
Last staff update: 24 June 2021

Copyright: 2019-2023,, Inc.

PubMed Search: Biphenotypic sinonasal sarcoma

Josephine K. Dermawan, M.D., Ph.D.
Laura O. Rabinowitz, M.D.
Page views in 2022: 5,766
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Cite this page: Dermawan JK, Rabinowitz LO. Biphenotypic sinonasal sarcoma. website. Accessed June 4th, 2023.
Definition / general
  • Low grade sarcoma of the sinonasal tract which features both neural (S100) and myogenic (actin) differentiation and the majority have been associated with PAX3 translocations
Essential features
  • Infiltrative, cellular, monomorphic spindled cell neoplasm with herringbone or fascicular architecture
  • May have prominent stromal vasculature
  • Positive for S100 (focal to diffuse), SMA/MSA, nuclear beta catenin immunohistochemical stains
  • Often recurrent PAX3 translocations most commonly partnered with MAML3
ICD coding
  • ICD-10: C30.0 - Malignant neoplasm of nasal cavity and middle ear
  • Sinonasal tract, with the upper nasal cavity or ethmoid sinus being the most commonly involved
  • May extend to cribriform plate or orbit
  • Unknown
Clinical features
  • Nonspecific, usually nasal obstructive symptoms manifesting as difficulty breathing, facial pressure, nasal congestion with or without pain
  • CT or MRI of the nasal sinuses
  • Diagnosis is by endoscopic biopsy, debulking or surgical resection
Radiology description
  • Heterogenous, enhancing sinonasal tract polyp or mass
  • Could present as destructive mass with extension into orbit or anterior skull base (J Neurol Surg Rep 2017;78:e15)
Radiology images

Contributed by Josephine K. Dermawan, M.D., Ph.D. and Laura O. Rabinowitz, M.D.

Superior nasal cavity mass (coronal)

Superior nasal cavity mass (transverse)

Prognostic factors
Case reports
  • Complete surgical resection with or without radiation
Gross description
  • Polypoid fragments of tan-yellow to soft gray tissue
Frozen section description
  • Diagnostic stromal features could be subtle on frozen sections
  • In the presence of benign epithelial proliferation, could be mistaken for an epithelial tumor such as sinonasal papilloma or respiratory epithelial adenomatoid hamartoma on frozen section (Head Neck Pathol 2020;14:33)
Frozen section images

Contributed by Josephine K. Dermawan, M.D., Ph.D. and Laura O. Rabinowitz, M.D.

Spindled cells with invaginated nests

Cellular spindled population

Microscopic (histologic) description
  • Infiltrative, cellular spindled cell proliferation
  • Medium to long fascicles with areas of herringbone pattern
  • Low grade, monotonous spindled cells with ovoid to elongated nuclei and inconspicuous nucleoli
  • Usually absence of high grade features such as nuclear pleomorphism, frequent mitoses, significant atypia, necrosis
  • Invagination or entrapment of benign surface respiratory epithelial proliferation with or without squamous metaplasia
  • Prominent stromal thick walled vasculature, could be hemangiopericytoma-like
  • Delicate stromal collagen
  • Subset of cases show focal rhabdomyoblastic elements (variable desmin, myogenin, myoD1) (Head Neck Pathol 2020;14:33)
Microscopic (histologic) images

Contributed by Josephine K. Dermawan, M.D., Ph.D. and Laura O. Rabinowitz, M.D.

Cellular spindle proliferation

Prominent stromal vasculature

Surface epithelial invaginations

Hemangiopericytoma-like vasculature

Herringbone pattern

Medium to long fascicles

Positive S100

Positive SMA

Negative CD34

Cytology description
  • Bland, uniform population of spindle cells with mildly enlarged, oval to spindle shaped nuclei with fine nuclear chromatin and inconspicuous nucleoli
  • Significant nuclear atypia or pleomorphism is typically absent (Diagn Cytopathol 2019;47:507)
Positive stains
Molecular / cytogenetics description
Sample pathology report
  • Soft tissue mass, right nasal cavity, excision:
    • Biphenotypic sinonasal sarcoma (see comment and synoptic report)
    • Comment: The nasal cavity mass shows a cellular spindled proliferation with areas showing a herringbone pattern. The spindle cells are low grade with slender to ovoid nuclei and inconspicuous nucleoli. There are invaginations of benign epithelium with squamous metaplasia. The neoplastic spindle cells show patchy S100, SMA and nuclear beta catenin immunohistochemical staining. They are negative for CD34, STAT6, SOX10 and cytokeratin AE1/AE3. These findings support the diagnosis of biphenotypic sinonasal sarcoma, a low-grade spindle cell sarcoma commonly associated with a PAX3-MAML3 gene fusion. This tumor type usually shows slow progressive growth and local invasion. While local recurrence is frequent, distant metastasis is very rare.
Differential diagnosis
Additional references
Board review style question #1

    A 45 year old woman presents with a 3 month history of nasal obstructive symptoms. An MRI of the nasal sinus shows a 3.8 cm polypoid mass in the ethmoid sinus with focal soft tissue extension without bony destruction of the cribriform plate. Histology reveals a low grade, monotonous spindle cell neoplasm. There is patchy immunoreactivity of S100 and SMA and negative staining for CD34, STAT6 and SOX10. Gene rearrangement involving which of the following genes is most commonly associated with this tumor?

  1. ETV6
  2. EWSR1
  3. NUTM1
  4. NTRK
  5. PAX3
Board review style answer #1
E. PAX3. Biphenotypic sinonasal sarcoma (shown here) is classically positive for S100 and actin, and is most frequently associated with PAX3 gene rearrangements, most commonly PAX3-MAML3. PAX3-NCOA1 and PAX3-FOXO1 translocations have also been reported.

Comment Here

Reference: Biphenotypic sinonasal sarcoma
Board review style question #2
    Which of the following features would favor a diagnosis of biphenotypic sinonasal sarcoma?

  1. Distant metastasis and death within several months of initial diagnosis
  2. Frequent mitoses and presence of necrosis
  3. Positive immunohistochemical reactivity for CD34
  4. Presentation in an adolescent or young male
  5. Uniform spindle cell proliferation with prominent stromal vasculature
Board review style answer #2
E. Uniform spindle cell proliferation with prominent stromal vasculature. Biphenotypic sinonasal sarcoma typically presents in middle aged women. Histologically, this entity is characterized by a cellular, monotonous spindle cell proliferation with low grade cytology that is positive for S100 and actin but negative for CD34 and STAT6. Prominent stromal vasculature could be present, sometimes reminiscent of hemangiopericytoma. Local recurrence is common but distant metastasis and death from disease remains rare.

Comment Here

Reference: Biphenotypic sinonasal sarcoma
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