Soft tissue
Uncertain differentiation
Extrarenal rhabdoid tumor


Topic Completed: 29 September 2020

Minor changes: 29 September 2020

Copyright: 2002-2020, PathologyOutlines.com, Inc.

PubMed Search: Rhabdoid tumor [title] soft tissue

See Also: Rhabdoid tumor of the kidney

Qurratulain Chundriger, M.B.B.S.
Nasir Ud Din, M.B.B.S.
Page views in 2019: 5,168
Page views in 2020 to date: 4,198
Cite this page: Chundriger Q, Ud Din N. Extrarenal rhabdoid tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissuerhabdoidtumor.html. Accessed October 28th, 2020.
Definition / general
  • Heterogeneous group of neoplasms unified by the presence of globular cytoplasmic inclusions, vesicular nuclei with prominent nucleoli and aggressive behavior
  • Response to therapy is poor
  • Metastasizes to lung, liver and lymph nodes early in the course of disease
Essential features
  • Abundant eosinophilic cytoplasm (due to hyaline globular inclusions of intermediate filaments) with eccentric vesicular nuclei and prominent nucleoli
  • Skeletal muscle markers and S100 negative
  • Karyotypic rearrangements of 22q11.2 resulting in homozygous inactivation of SMARCB1 (hSNF5 / INI1), with subsequent loss of INI1 nuclear expression by immunohistochemistry
Terminology
  • Malignant rhabdoid tumor (synonym)
ICD coding
  • ICD-O: 8963/3 - rhabdoid tumor, NOS
  • ICD-11: 2B5F.2 & XH3RF3 - sarcoma, not elsewhere classified of other specified sites & malignant rhabdoid tumor
Epidemiology
  • Genuine rhabdoid tumors exclusively belong to the pediatric age group and are very rare
  • Adult cases represent expression of a particular phenotype, which can occur in any type of sarcoma or even carcinoma but it is virtually universally associated with an aggressive course
  • Mean age at diagnosis < 1 year for tumors with germ line SMARCB1 alterations and 1.5 years for sporadic tumors (Crit Rev Oncog 2015;20:199)
  • M = F
Sites
Pathophysiology
Clinical features
  • Clinical presentation is related to the site of involvement
  • Intraocular tumors present with proptosis (J Pediatr Hematol Oncol 2020;42:228)
  • Deep / visceral involvement causes local pain and pressure symptoms and may result in loss of function of an anatomic site if local neural bundle / plexus is compromised (Brain Dev 2017;39:717)
Diagnosis
  • Rhabdoid cell morphology in a pediatric tumor along with loss of INI1
  • Requires thorough sampling and immunohistochemical studies to rule out rhabdoid phenotype in another underlying tumor, particularly in adult cases (Mod Pathol 2016;29:1232)
  • Demonstration of 22q11.2 mutations in a tumor with well developed rhabdoid morphology (Genes Chromosomes Cancer 2011;50:379)
Radiology description
Radiology images

Images hosted on other servers:

Intratumoral hemorrhage, bone erosion

Lobulated mediastinal mass

Multilobulated hyperintense mass

Prognostic factors
Case reports
Treatment
  • No definite chemotherapy regimen is available; some cases report successful therapy using alkaloids, platinum agents and combinations of chemotherapy, surgery and radiation (Crit Rev Oncog 2015;20:199)
  • Targeted therapy is under investigation, utilizing various epigenetic pathways including DNA and histone methylation, histone deacetylation, cell cycle arrest and antimitotic mechanisms (Crit Rev Oncog 2015;20:199)
Clinical images

Images hosted on other servers:

Ulcerating tumor at heel

Gross description
  • Tumor is infiltrative with a tan-white solid appearance
  • Calcifications and hemorrhage may be seen (Urology 2020;137:164)
Gross images

Contributed by Mark R. Wick, M.D.

Superficial, subcuticular



Images hosted on other servers:

Polypoid mass with hemorrhage

Frozen section description
  • Frozen sections are rarely performed and show sheets of cells with typical rhabdoid appearance and vesicular nuclei with nucleoli
Microscopic (histologic) description
  • Tumor cells have classic rhabdoid or skeletal-like profile, comprised of abundant cytoplasm with eosinophilic hyaline globules and vesicular nuclei with prominent nucleoli (Anticancer Res 2005;25:4573, Ann Diagn Pathol 2012;16:504)
  • Some cases may show areas of spindling of tumor cells
  • Nuclear pleomorphism can be prominent
  • Background stroma may be variably myxoid to fibromyxoid
  • Tumor necrosis and mitotic activity can be variable
Microscopic (histologic) images

Contributed by Nasir Ud Din, M.B.B.S.
Rhabdoid cells

Rhabdoid cells

Prominent nucleoli

Prominent nucleoli

Sheet-like growth

Sheet-like growth

Nuclear pleomorphism

Nuclear pleomorphism

Spindling of tumor cells

Spindling of tumor cells

Myxoid stroma

Myxoid stroma


Fibromyxoid stroma

Fibromyxoid stroma

Tumor necrosis

Tumor necrosis

EMA

EMA

CD99

CD99

CD56

CD56

SALL4

SALL4


Loss of nuclear INI1 Loss of INI1

Loss of INI1

Cytology description
  • Variably cellular smears with individual cells and structureless clusters of rhabdoid cells, spindle cells or round cells
  • Cytoplasmic inclusions are eosinophilic on Giemsa and pale gray on Papanicolaou stain (Indian J Pathol Microbiol 2011;54:819)
  • Differentials on cytology include extrarenal Wilms tumor, rhabdomyosarcoma, spindle cell sarcoma and round blue cell tumors including lymphoma (Indian J Pathol Microbiol 2011;54:819)
Cytology images

Contributed by Mark R. Wick, M.D.
Rhabdoid cells in smears

Rhabdoid cells in smears



Images hosted on other servers:

Giemsa and Papanicolaou stains

Positive stains
Negative stains
Electron microscopy description
Electron microscopy images

Images hosted on other servers:

Cytoplasmic whorls

Molecular / cytogenetics description
Molecular / cytogenetics images

Images hosted on other servers:

Homozygous deletion on MLPA

Sample pathology report
  • Right arm, excision:
    • Extrarenal rhabdoid tumor (see comment)
    • Comment: Tumor cells are rhabdoid in appearance with eccentric nuclei. Positive cytokeratin, negative skeletal markers and loss of INI1 are seen. 22q11.2 mutation confirms the diagnosis.
Differential diagnosis
In children:
  • Rhabdomyosarcoma:
    • Embryonal rhabdomyosarcoma:
      • Common in children < 10 years old
      • M > F
      • Most common sites: head and neck region, genitourinary region
      • May have rhabdomyoblasts / strap cells with cross striations
      • May show eccentric cytoplasm similar to extrarenal rhabdoid tumor
      • Shows positive staining for markers of skeletal differentiation (desmin, myogenin and MyoD1)
      • Retained nuclear INI1
    • Alveolar rhabdomyosarcoma:
      • Occurs in adolescents and young adults
      • Grows as alveoli-like spaces formed by loss of cohesion centrally
      • Monomorphic round cells with hyperchromatic nuclei and scant cytoplasm
      • Strong and diffuse desmin and myogenin positivity
      • May express focal / weak cytokeratins (5 - 50% cases)
      • Intact nuclear INI1
  • Ewing sarcoma:
    • Shows sheet-like growth of round blue cells with scant cytoplasm and hyperchromatic nuclei
    • Diffuse CD99 and NKX2.2 expression
    • Retained nuclear INI1
    • May show cytokeratin positivity in up to 20% cases
    • EWSR1 mutations are diagnostic
  • Desmoplastic round blue cell tumor:
    • Mean age 25 years
    • M > F
    • Abdominal cavity is the most common site
    • Contains prominent desmoplastic stroma
    • Round cells grow in nodules separated by stroma
    • May show polyphenotypic differentiation with positive keratins, vimentin, desmin, CD56, NSE and nuclear WT1
    • Retained nuclear INI1
    • EWSR1-WT1 gene fusion is consistent

In adults:
  • Extrarenal rhabdoid tumor should be considered only after other tumors with a rhabdoid appearance have been ruled out
  • Carcinoma:
    • Age over 50, a history of carcinoma and areas of cohesive epithelial differentiation help in reaching correct diagnosis
  • Malignant melanoma:
    • Nonpigmented melanoma mimics rhabdoid tumor
    • Occurs in older age group
    • Positive melanocytic markers HMB45, MelanA and negative cytokeratins
  • Anaplastic large cell lymphoma:
    • May occasionally exhibit rhabdoid features
    • Positive for CD30, weak / focal positive for CD45 / LCA and CD3 and negative for keratins
  • Proximal type epithelioid sarcoma:
    • Positive for keratins, CD34 (50% cases) and may show loss of nuclear INI1
    • Harbors mutations of 22q11 with resultant abnormalities of SMARCB1 but the mechanism of these mutations is different than that underlying extrarenal rhabdoid tumors
Board review style question #1

A 2 month old baby presented with a progressively enlarging soft tissue mass in the right axillary region. Microscopic examination of the resected tumor showed morphology depicted in the picture. Immunohistochemical stains to help reach a diagnosis are

  1. Negative desmin and nuclear INI1
  2. Negative vimentin and positive S100
  3. Positive cytokeratin and CD34
  4. Positive cytokeratin and desmin
  5. Positive cytokeratin and negative vimentin
Board review answer #1
A. Negative desmin and nuclear INI1. This is an extrarenal rhabdoid tumor.

Comment Here

Reference: Extrarenal rhabdoid tumor
Board review style question #2
Homozygous inactivation of SMARCB1 seen in extrarenal rhabdoid tumors are due to mutations in

  1. 9q22
  2. 11p13
  3. 11q24
  4. 21q12
  5. 22q11
Board review answer #2
Back to top
Image 01 Image 02