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Clinical calculator summary

Original Enneking/MSTS Stage

Historical surgical staging based on histologic grade, anatomical compartment, and metastasis.

Evidence-based context for fast calculator use

Purpose:
Reproduce the original 1980 Stage IA, IB, IIA, IIB, or III classification.
Population:
Primary malignant musculoskeletal sarcoma with specialist pathological and anatomical assessment.
Factors:
G1 versus G2 grade, T1 versus T2 compartment, M0 versus M1 metastasis
Reference:
Enneking WF, Spanier SS, Goodman MA. Clin Orthop Relat Res. 1980;(153):106-120.
HomeEnneking Staging (Bone/Sarcoma)
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Enneking Staging (Bone/Sarcoma)

Clinical Context & Background

This calculator implements the original 1980 Enneking/Musculoskeletal Tumor Society surgical staging system for primary malignant musculoskeletal sarcoma. It combines G1 low-grade or G2 high-grade histology with T1 intracompartmental or T2 extracompartmental extent when M0 is confirmed. Any regional or distant metastasis is Stage III regardless of grade or compartment. A discontinuous skip lesion is treated as metastatic disease and entered as M1.
T1 means the tumor remains within a clearly defined anatomical compartment; T2 means extension outside that compartment. Grade and compartment require specialist pathological and imaging assessment. Do not use this calculator for benign tumors, metastatic carcinoma, lymphoma, myeloma, or other non-sarcoma bone lesions. Do not automatically apply it to recurrent or previously treated tumors.
This historical system does not replace contemporary AJCC/UICC staging, histology-specific staging, or multidisciplinary sarcoma review, and it does not independently determine surgical margins or treatment.
Primary Source EvidenceEnneking WF, Spanier SS, Goodman MA. Clin Orthop Relat Res. 1980;(153):106-120. DOI: 10.1097/00003086-198011000-00013.
Formula Logic
Original 1980 Enneking/MSTS surgical stage: G1/T1/M0 = IA; G1/T2/M0 = IB; G2/T1/M0 = IIA; G2/T2/M0 = IIB; any M1 regional or distant metastasis, including a discontinuous skip lesion, = III.

Reference Data

StageOriginal Enneking/MSTS definition
IAG1 low grade, T1 intracompartmental, M0
IBG1 low grade, T2 extracompartmental, M0
IIAG2 high grade, T1 intracompartmental, M0
IIBG2 high grade, T2 extracompartmental, M0
IIIAny grade and extent with M1 regional or distant metastasis, including a skip lesion

Clinical Workflow

Use, Interpret, And Continue The Patient Pathway

Expand for workflow guidance, limitations, examples, and related next steps.

When To Use

  • For a primary malignant musculoskeletal sarcoma after specialist grade, compartment, and metastatic assessment.
  • Use only when all three source-defined categories can be assigned explicitly.

How To Interpret

  • With M0, G1 maps to Stage I and G2 maps to Stage II; T1 gives subtype A and T2 gives subtype B.
  • Any M1 regional or distant metastasis, including a discontinuous skip lesion, maps to Stage III.

What To Do Next

  • Document the pathological grade, anatomical basis for compartment status, and metastatic assessment.
  • Record contemporary AJCC/UICC or histology-specific staging separately and review in a sarcoma multidisciplinary team.

Limitations

  • Not for benign tumors, metastatic carcinoma, lymphoma, myeloma, or non-sarcoma bone lesions.
  • Do not automatically apply to recurrent or previously treated tumors.
  • Compartment status can be difficult to define at some anatomical sites and requires specialist assessment.
  • The stage does not independently prescribe a surgical margin, systemic therapy, or other treatment.

Validated Population

Primary malignant musculoskeletal sarcoma in the historical Enneking/MSTS source context.

Skip lesion present

A discontinuous skip lesion is represented as M1; metastasis takes precedence and the result is Stage III.

Calculation verification history

Verified

  1. : Production browser revalidation

    • Five source-backed Enneking/MSTS cases were exercised on the public production route through visible controls; 5/5 expected stages matched, covering IA, IB, IIA, IIB, and III.
    • No unexpected N/A, literal undefined value, stale control, or browser-console error was observed.
    Download latest production check (Excel)

    Case-level evidence is retained in validation/browser-revalidation/bone-sarcoma-enneking-staging-2026-08-03.json.

  2. : Local browser remediation verified; production retest pending

    • Ten source-backed cases passed through visible controls across 11 submissions, covering all eight G/T/M source combinations, missing metastasis, and reset/repeat.
    • Histologic grade, local extent, and metastasis now render their defined trace values with a neutral published-rule decision; no literal undefined value appeared.
    • The original production UI and hydration findings remain open until deployment and public revalidation.

    Case-level local remediation evidence is retained in validation/browser-production/bone-sarcoma-enneking-staging.local-remediation.json.

  3. : Production browser validation

    • Ten source-backed cases were exercised on the public production route through visible browser controls; 1/10 case records passed their expected-versus-observed assertions across 11 visible submissions.
    • Overall browser status: failed-ui-and-console. high: Every valid Enneking result displayed three bold literal `undefined` values beneath Histologic grade, Local extent, and Metastasis, although the stage headline and interpretation were correct. | medium: Production emitted minified React error #418 during route loads/reloads used by this run.
    • Case-level inputs, expected and observed results, reset/repeat behavior, failure reproductions, and console evidence are retained in the production-browser evidence record.

    Case-level production evidence is retained in validation/browser-production/bone-sarcoma-enneking-staging.json.

  4. : Full validation test

    • 192/192 exhaustive source-table, independent-oracle, UI, strict-input, trace, scope, registry, report, and isolation checks passed.
    • This verifies implementation of the selected historical staging system, not independent clinical validation, current AJCC/UICC staging, prognosis, or treatment selection.

  5. : Calculation and input-contract correction

    • Removed favorable defaults, Number coercion, invalid-input fallthrough, and unsupported stage-derived treatment or surgical-margin instructions.
    • Required exact G1/G2, T1/T2, and M0/M1 assessments; any M1, including a discontinuous skip lesion, takes precedence and maps to Stage III.
    • Added compartment definitions, source population and exclusions, specialist-assessment cautions, and explicit coexistence with contemporary AJCC/UICC staging.

    Included in the current validation report.

Verification confirms the calculator implementation against the cited model; it is not independent clinical validation, regulatory approval, or medical advice.

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Frequently Asked Questions

What is a compartment in this system?

T1 is confined within a clearly defined anatomical compartment; T2 extends outside it. Specialist imaging and surgical assessment are required.

How is a skip lesion handled?

A discontinuous skip lesion is treated as metastatic disease in this implementation and should be entered as M1, which maps to Stage III.

Does Enneking staging replace AJCC staging?

No. Contemporary AJCC/UICC and histology-specific staging should be documented separately where applicable.

Evidence-based oncology decision support. Verify with clinical guidelines.