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Frozen section — intraoperative pathology consultation
A frozen section is meant to answer during surgery one question that will change the operation — is there malignancy, are the margins clear, is the node involved, is there diagnostic tissue — and it is not a substitute for the final diagnosis on paraffin; when the answer will not change anything in the operation, it should not be done.
Why it matters in the exam
The bank asks when a frozen section is appropriate and when it is not. Good indications: establishing malignancy in a mass whose result will decide the extent of resection (for example a lung nodule in a wedge resection before lobectomy), margin assessment, sentinel node assessment when the result will change the operation, and tissue identification — for example confirming that a parathyroid gland was removed or that a biopsy contains diagnostic tissue. The accepted time for one block is about 20 minutes from receipt of the specimen to the report to the surgeon.
Situations in which frozen section is problematic: fat-rich tissue (fatty breast) does not freeze well; bone and calcified tissue cannot be cut; a very small lesion may be "used up" in freezing and leave no tissue for the final diagnosis; a follicular thyroid lesion requires examination of the whole capsule for invasion, so frozen section is usually not decisive; and lymphoma requires full classification on paraffin and further tests, but frozen section can confirm suitable tissue and direct its triage (culture, molecular tests, flow cytometry).
Frozen-section accuracy is high, but there is a small rate of discordance with the final diagnosis and a rate of "deferral to paraffin" when there is uncertainty; a good pathologist knows to say "cannot be determined" rather than guess. Artifacts: ice crystals that distort nuclei and fat. Communication must be clear: the answer is given directly to the surgeon, read back, and documented with the time. In cases suspected of tuberculosis or prion disease, special care is taken because of contamination of the instrument.
Key points
- Frozen section only when the answer changes the operation.
- Indications: malignancy, margins, sentinel node, tissue identification.
- Unsuitable: fat, bone, follicular thyroid lesion, tiny lesion.
- In lymphoma: confirm tissue and triage.
- About 20 minutes for one block; direct communication and read-back.
Summary table
| Situation | Suitable for frozen section? | Reason | Alternative |
|---|---|---|---|
| Lung nodule before lobectomy | Yes | The answer changes the operation | — |
| Margins and sentinel node | Yes, when the result will change the operation | Immediate decision | Paraffin to confirm |
| Fatty breast, bone | No | Do not freeze or cut well | Paraffin |
| Follicular thyroid lesion | Usually not | Whole capsule needed | Paraffin |
| Suspected lymphoma | Only to confirm tissue and triage | Classification needs further tests | Flow cytometry and paraffin |
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Sources
- Rosai and Ackerman's Surgical Pathology, 11th edition (2018) — Intraoperative consultation
- College of American Pathologists: Q-Probes studies on frozen section turnaround and accuracy, 2015 — Benchmarks for turnaround and discordance
- Taxy JB, Husain AN, Montag AG. Biopsy Interpretation: The Frozen Section, 2nd edition (2014) — Indications and pitfalls
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.