Frozen Section: An Invaluable Tool for Intra-Operative Surgical Consultation

PATHCHAT Edition No. 42
Please contact your local Ampath pathologist for more information.

Author: Dr. Jackie Chokoe-Maluleke

History of the Frozen Section Technique

✅ Evolution of the Frozen Section:

• 1818: Dutch anatomist Pieter de Reimer used cold brine (saltwater) to harden tissues.
• 1895: Thomas Cullen, MD, published the first documented frozen section technique at Johns Hopkins.
• 1905: Dr. Louis B. Wilson standardized the freezing, cutting, and staining steps using a Spencer automatic freezing microtome with a CO₂ attachment.
• Wilson’s method, published in the Journal of the American Medical Association (1905), is still in use today.

📌 The frozen section technique remains a cornerstone of intra-operative pathology consultation.

Method: How Frozen Section is Performed

✅ Step-by-Step Process:

1. Surgeon collects fresh tissue in the operating theatre.
2. Tissue is handed to the histopathologist for processing.
3. Tissue is taken to a cryostat room adjacent to the theatre or pathology laboratory.
4. Specimen dimensions are recorded, and a cytologic imprint or scraping may be performed.
   • Cytology is done by scraping the fresh tissue onto a glass slide and staining it with Papanicolaou or Giemsa stains.
5. Tissue is rapidly frozen using a frozen aerosol spray inside a cryostat (-20°C to -30°C).
6. Sections (5–10 μm thick) are cut and mounted onto glass slides.
7. Slides are stained with a modified Hematoxylin & Eosin (H&E) stain.
8. Slides are mounted with a fast-drying synthetic resin mounting medium.
9. Pathologist examines the slides under a microscope.
10. Findings are relayed to the surgeon in the operating room.

• If the lab is near the theatre, the pathologist may deliver results in person.
• If not, results are telephonically communicated.

📌 The entire frozen section process typically takes 20 minutes from specimen receipt to diagnosis.

Key Concepts in Frozen Section Analysis

✅ Best Practices for Accurate Diagnosis:

• Surgeon and pathologist should discuss cases 1–2 days before surgery.
• Previous biopsy slides should be reviewed before surgery.
• Radiological images (CT, MRI) should be assessed, especially in bone, soft tissue, and CNS cases.
• Frozen section does NOT replace formal paraffin-embedded histology.
• Frozen sections should NOT be treated as emergency procedures.
• Pathologist must determine if frozen section is necessary.

📌 Communication between the surgeon and pathologist is critical for optimal use of frozen section services.

Indications for Frozen Section

✅ Reasons for Requesting a Frozen Section:

• To determine the nature of a lesion (benign vs. malignant).
• To confirm the presence of a lesion.
• To ensure an adequate biopsy sample is collected.
• To establish the histological grade of a malignant lesion.
• To confirm synchronous (multiple) lesions.
• To determine the organ of origin in metastatic tumours.
• To assess adequacy of surgical margins.
• To confirm invasion in cases of suspected malignancy.
• To identify infectious processes in biopsy material.
• To obtain fresh tissue for molecular, genetic, or electron microscopy studies.

📌 Frozen section is used when rapid intra-operative decisions are needed.

Limitations of Frozen Section

🚨 Potential Errors in Frozen Section Analysis:

1. Sampling Errors

• Poor specimen selection by the surgeon.
• Necrotic or degenerated tumour tissue.
• Difficulty in assessing invasion in follicular thyroid carcinoma.
• Missed malignant components in ovarian teratomas.

2. Technical Problems

• Freezing artefacts causing distortion.
• Inadequate xylene treatment leading to poor staining.
• Cellular bloating due to rapid freezing.
• Sections too thick, affecting clarity.

3. Interpretation Errors

• Tumours that are challenging to classify (e.g., angiosarcoma, signet ring carcinoma).
• Heterogeneous tumours with mixed histological components.
• Difficulty differentiating hyperplastic vs. neoplastic changes in lymph nodes.
• Assessing ganglion cells in Hirschsprung’s disease.

📌 If a diagnosis cannot be reached due to artefacts or sample limitations, a formal paraffin section must be used.

Conclusion

✅ Frozen section is an essential intra-operative diagnostic tool, influencing surgical decisions in real time.
✅ It should NOT replace permanent section histology but rather guide intra-operative management.
✅ Pathologist-surgeon communication is crucial for maximizing diagnostic accuracy.
✅ Frozen sections should only be performed when results will change surgical management.

📌 If an operation can proceed without waiting for frozen section results, then the request was not warranted in the first place.

References

1. Gal, AA. (2005). The centennial anniversary of the frozen section technique at the Mayo Clinic. Archives of Pathology and Laboratory Medicine, 129(12): 1532–1535.
2. Jaafar, H. (2006). Intraoperative frozen section consultation: Concepts, applications, and limitations. Malaysian Journal of Medical Sciences, 13(1).

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