Stanford School of Medicine

Surgical Pathology Criteria

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Extrarenal Rhabdoid Tumor


  • Neoplasm composed of large noncohesive cells with keratin positive paranuclear inclusions
  • Other recognized types of neoplasms must be excluded

Diagnostic criteria

  • Sheets of poorly cohesive cells
  • Large polygonal or spindled cells
  • Abundant glassy eosinophilic cytoplasm
    • Paranuclear eosinophilic inclusions
      • May be focal or widespread, occasionally not easy to find
      • May be weakly PAS positive
      • Keratin positive
      • Usually vimentin positive
  • Large eccentric vesicular nucleus
    • Round or bean shaped
    • Large, prominent nucleolus
  • Mitotic rate frequently high
  • Other neoplasms must be excluded
    • Particularly, metastatic carcinoma and melanoma must be excluded
    • Specifically, a strict definition does not permit reactivity for:
      • Desmin, actin or myoglobin
        • Neoplasms with positivity of these markers should be diagnosed as rhabdomyosarcoma even if keratin positive
      • S100
      • Neurofilament
    • Neoplasms not fulfilling all of these strict criteria may be designated as malignant neoplasm with rhabdoid features
  • Extrarenal rhabdoid tumor is histologically identical to renal rhabdoid tumor

Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting:: September 15, 2007
Latest update: December 12, 2008


Supplemental studies


  • Inclusions are keratin positive 100% (definitional)
  • EMA Frequently positive
  • Vimentin >95% positive
  • INI1 loss in 85%
  • Many studies report reactivity for some of the following, but a strict definition of extrarenal rhabdoid tumor does not permit such antigen expression:
    • Desmin, actin, myoglobin Negative
    • S100, HMB45 Negative
    • Neurofilament, GFAP Negative
    • CD34 Negative

Genetic analysis

  • Abnormalities of chromosome 22 have been demonstrated by various techniques:
    • Monosomy or deletion of the long arm of chromosome 22
    • Translocations involving chromosome 22q11

Differential Diagnosis

Carcinomas may mimic extrarenal rhabdoid tumors and in rare cases be morphologically indistinguishable

  • The following features favor carcinoma
    • Age over 50 years
    • Areas exhibiting cohesive epithelial differentiation
    • History of carcinoma
  • Identification of abnormalities of the long arm of chromosome 22 supports rhabdoid tumor

Melanomas may mimic extrarenal rhabdoid tumors and in rare cases be morphologically indistinguishable

  • Any of the following features of melanoma rule out a diagnosis of rhabdoid tumor
    • History of melanoma
    • S100 or HMB45 reactivity
    • Keratin negativity
  • Identification of abnormalities of the long arm of chromosome 22 supports rhabdoid tumor

Anaplastic Large Cell Lymphoma Extrarenal Rhabdoid Tumor
LCA and or T lineage markers positive LCA and T lineage markers negative
Keratin rare, faint Keratin 100% positive
CD30, ALK positive No data available for CD30, ALK
INI1 expressed 100% (few tested) INI1 loss 85%
Translocation of chromosome 2 short arm Various deletions, translocations involving 22q11
LCA and T lineage markers are occasionally undetectable in ALCL

Extrarenal Rhabdoid Tumor Proximal Type Epithelioid Sarcoma
CD34 negative CD34 50% positive
No intensely eosinophilic collagen Intensely eosinophilic collagen
Median age 8-9 years Median age 35-40 years
Wide range of sites Predilection for genitalia
It is probable that malignant rhabdoid tumors do not occur in adults - most if not all are carcinoma, melanoma or proximal epithelioid sarcoma

Rhabdomyosarcoma Extrarenal Rhabdoid Tumor
Desmin, actin, myoglobin or MyoD1 positive Muscle markers negative (definitional)
Keratin 5-50% positive, focal, weak Keratin 100% (definitional)
INI1 expression retained 100% INI1 loss 85% nearly definitional
May have cross striations No cross striations
May have strap cells Strap cells rare
No consistent abnormalities of 22q Various deletions, translocations involving 22q11 may be seen
Both have eccentrically located eosinophilic cytoplasm

Extrarenal Rhabdoid Tumor Desmoplastic Small Cell Tumor
No desmoplastic stroma Prominent desmoplastic stroma
Desmin negative Desmin positive
INI1 loss 85% INI1 expressed 100%
Median age 8-9 years Mean age 25 years
Various deletions, translocations involving 22q11 t(11;22)(p13;q12)
Both may be rhabdoid and express keratin


  • Age range congenital to 56 years
    • Mean age 8-9 years
    • Rare in adults
      • Many purported examples in adults are metastatic carcinoma or melanoma
  • Wide range of sites, soft tissue and organs
  • Metastases to lung, bone, lymph node
  • 5 year survival 15%

Grading / Staging / Report

According to the guidelines of the ADASP, extrarenal rhabdoid tumor is definitionally high grade

French Federation of Cancer Centers System grading scheme for adult sarcomas

  • Tumor differentiation score = 3 for extrarenal rhabdoid tumor
  • Mitotic index
    • Score 1 0-9 mitoses per 10 hpf (0.1744 sq mm)
    • Score 2 10-19 mitoses per 10 hpf
    • Score 3 >19 mitoses per 10 hpf
  • Tumor cell necrosis
    • Score 0 No necrosis on any slide (one slide per 2 cm tumor diameter)
    • Score 1 <50% of tumor is necrotic on slides examined
    • Score 2 >50% of tumor is necrotic on slides examined
  • Final Grade (add the three scores above)
    • Grade 1 Sum of scores = 2 or 3
    • Grade 2 Sum of scores = 4 or 5
    • Grade 3 Sum of scores = 6 or more

Use TNM Staging

The surgical pathology report should contain or address the following:

  • Location
  • Type of resection or biopsy
  • Histologic diagnosis
  • Managerial category III (Local recurrence common, metastasis may occur) or IV (widespread disease assumed to be present at outset)
  • Grade: High (by definition)
  • Stage
  • Extent of tumor cell necrosis
  • Size
  • Depth (dermis, subcutis, below fascia, body cavity)
  • Margins
    • Involved
    • Not involved
      • If under 2 cm give all such distances and sites
      • If over 2 cm give minimum distance and site
  • Results of supplementary studies if performed
  • Relationship to other specimens from the same patient


Keratin positive soft tissue tumors (frequent and strong)


  • Kempson RL, Fletcher CDM, Evans HL, Henrickson MR, Sibley RS. Tumors of the Soft Tissues, Atlas of Tumor Pathology, AFIP Third Series, Fascicle 30, 2001
  • Fletcher CDM, Unni KK, Mertens F. Pathology and Genetics of Tumours of Soft Tissue and Bone, World Health Organization Classification of Tumours 2002
  • Weiss SW, Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors, 4th edition, 2001
  • Fanburg-Smith JC, Hengge M, Hengge UR, Smith JS Jr, Miettinen M. Extrarenal rhabdoid tumors of soft tissue: a clinicopathologic and immunohistochemical study of 18 cases. Ann Diagn Pathol 1998 Dec;2(6):351-62
  • Parham DM, Weeks DA, Beckwith JB. The clinicopathologic spectrum of putative extrarenal rhabdoid tumors. An analysis of 42 cases studied with immunohistochemistry or electron microscopy. Am J Surg Pathol 1994 Oct;18(10):1010-29
  • Hoot AC, Russo P, Judkins AR, Perlman EJ, Biegel JA. Immunohistochemical analysis of hSNF5/INI1 distinguishes renal and extra-renal malignant rhabdoid tumors from other pediatric soft tissue tumors. Am J Surg Pathol. 2004 Nov;28(11):1485-91.
  • Bourdeaut F, Fréneaux P, Thuille B, Lellouch-Tubiana A, Nicolas A, Couturier J, Pierron G, Sainte-Rose C, Bergeron C, Bouvier R, Rialland X, Laurence V, Michon J, Sastre-Garau X, Delattre O. hSNF5/INI1-deficient tumours and rhabdoid tumours are convergent but not fully overlapping entities.
    J Pathol. 2007 Feb;211(3):323-30.
  • Hornick JL, Dal Cin P, Fletcher CD. Loss of INI1 Expression is Characteristic of Both Conventional and Proximal-type Epithelioid Sarcoma. Am J Surg Pathol. 2009. [Epub ahead of print]
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