Soft tissue

Skeletal muscle

Rhabdomyosarcoma

Spindle cell / sclerosing rhabdomyosarcoma


Editorial Board Member: Nasir Ud Din, M.B.B.S.
Deputy Editor-in-Chief: Borislav A. Alexiev, M.D.
Erica Kao, M.D.
Cecilia Belzarena, M.D, M.P.H.

Last author update: 6 April 2023
Last staff update: 6 April 2023

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PubMed Search: Sclerosing rhabdomyosarcoma

Erica Kao, M.D.
Cecilia Belzarena, M.D, M.P.H.
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Cite this page: Kao E, Belzarena C. Spindle cell / sclerosing rhabdomyosarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissuesclerosingrhabdo.html. Accessed April 15th, 2024.
Definition / general
  • Spindle cell / sclerosing rhabdomyosarcoma (RMS) is a rare type of rhabdomyosarcoma characterized by fascicular spindle cell morphology
  • Subclassification depends on the presence of genetic alterations associated with prognosis
  • Predilection for the head and neck / extremities
  • 5 - 10% of RMS (Arch Pathol Lab Med 2015;139:1281)
Essential features
  • Rhabdomyosarcoma with prominent fascicular spindle cell or sclerosing features
  • Relatively similar morphology but a genetically and clinically heterogeneous disease, especially in the pediatric population
  • Tumors with VGLL2, NCOA2 and CITED2 gene rearrangements typically arise in infants and have a favorable prognosis (Am J Surg Pathol 2016;40:224)
  • Tumors with MYOD1 mutations usually arise in adolescents and adults and have an unfavorable prognosis (Mod Pathol 2019;32:27)
  • Tumors with TFCP2::NCOA2 gene rearrangements can be intraosseous (Mod Pathol 2020;33:404)
Terminology
  • Spindle cell / sclerosing are considered the same diagnostic variant of rhabdomyosarcoma
ICD coding
  • ICD-O: 8912/3 - spindle cell rhabdomyosarcoma
  • ICD-11: 2B55.Z & XH7NM2 - rhabdomyosarcoma, unspecified primary site & spindle cell rhabdomyosarcoma
Epidemiology
  • M > F
Sites
Pathophysiology
Clinical features
Diagnosis
Radiology description
Radiology images

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Large masticator space mass in neck

Cranial MRI

CT scan

MRI

Prognostic factors
Case reports
Treatment
Clinical images

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Cystic mass

Gross description
  • Variably circumscribed tumor with a tan, sometimes whorled cut surface
Microscopic (histologic) description
  • Fascicles of spindle cells with a herringbone growth pattern resembling leiomyosarcoma or fibrosarcoma
  • Primitive undifferentiated areas with round cells and hyperchromatic nuclei may focally be present
  • Tadpole or strap cells and rhabdomyoblasts can be seen in some cases
  • Sclerosing RMS shows prominent hyalinization / sclerosis; tumor cells in cords, nests or trabeculae in a pseudovascular growth pattern
  • In bone, there can be epithelioid cells in sheets and fascicles in addition to the typical spindle cell morphology (Histopathology 2018;73:514)
Microscopic (histologic) images

Contributed by Erica Kao, M.D. and Borislav A. Alexiev, M.D.

Sclerotic and collagenous stroma

Fascicular growth

MyoD1

Positive stains
Molecular / cytogenetics description
Sample pathology report
  • Soft tissue, neck, biopsy:
    • Rhabdomyosarcoma with spindle cell features (see comment)
    • Comment: The biopsy contains cellular fascicles of tumor cells that are strongly positive for desmin, myogenin and MyoD1. Molecular testing will be performed for further subtyping and reported in an addendum.
Differential diagnosis
Board review style question #1
Which soft tissue tumor is more commonly found in the head and neck region?

  1. Angiolipoma
  2. Dermatofibrosarcoma protuberans
  3. Liposarcoma
  4. Spindle cell / sclerosing rhabdomyosarcoma
Board review style answer #1
D. Spindle cell / sclerosing rhabdomyosarcoma

Comment Here

Reference: Spindle cell / sclerosing rhabdomyosarcoma
Board review style question #2

Which soft tissue tumor is shown in the image above and is associated with fascicular spindle cell morphology?

  1. Alveolar rhabdomyosarcoma
  2. Embryonal rhabdomyosarcoma
  3. Pleomorphic rhabdomyosarcoma
  4. Spindle cell / sclerosing rhabdomyosarcoma
Board review style answer #2
D. Spindle cell / sclerosing rhabdomyosarcoma. Fascicular spindle cell morphology is one of the essential features of spindle cell / sclerosing rhabdomyosarcoma.

Comment Here

Reference: Spindle cell / sclerosing rhabdomyosarcoma
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