Frozen Section Diagnosis

Transcription

1 Frozen Section Diagnosis Dr Catherine M Corbishley Honorary Consultant Histopathologist St George s Healthcare NHS Trust and lead examiner final FRCPath Practical

2 Frozen Section Diagnosis The Pathologist on the Spot Part of Pathology practice since 1905 (Mayo Clinic) Peak use in 1970s-80s Decreasing use since better preoperative imaging and biopsy diagnosis Still a number of important indications and uses An essential skill for a practicing pathologist Part of the Final FRCPath exam practical in UK

3 Uses and Abuses of Frozen sections Appropriate indications An intraoperative consultation that will make a difference to the procedure performed To avoid subsequent surgical procedures Primary diagnosis when there is no preoperative diagnosis Staging, if this is not possible by other means Surgical margin status Unexpected additional findings

4 Idle surgical curiosity To tell the patient when they wake up (more common in the private sector) For detailed tumour subclassification (but not always the case) As an excuse for inadequate preoperative investigations Because the surgeon has a BTA (been to America) When there is risk of significant infection (TB, HIV, Hep B or C) unless you have the facilities and agreed protocol Uses and Abuses of Frozen sections Inappropriate indications

5 What does the Pathologist need to know? What is the Question being asked by the surgeon? What exactly are they dealing with? What have they sent and where exactly is it from? Where are they so I can talk to them about the result?

6 What does the Pathologist need to know? training and experience Any relevant previous history or investigations (check lab records/slides) The normal appearances of the tissues being sampled Which conditions might occur at this site Frozen section artefact appearances at this site The limitations of what can be determined at frozen section

7 What does the pathologist have to do? Tissue selection maximum (or minimum) size if possible get the surgeon to do this Tissue type (some tissues cut better than others) - avoid fatty or bony tissues Quality considerations don t press and prod the specimen this produces artefacts Time considerations don t take too long (anaesthetic risks etc) Communication be clear and precise in what you tell the surgeon (avoid pathological irrelevancies and esoteric terms)

8 Common Problems Benign or Malignant Small lung lesions with no preop diagnosis Ovarian cystic lesions Incidental findings - liver nodules found during GI surgery Gynae tumours vs Endometriosis Indeterminate Testicular lesions

9 Common Problems- Subtyping Carcinoma or Lymphoma or other eg Melanoma Non small cell or small cell (lung) Primary or Metastatic (lung and other sites) BE AWARE OF YOUR LIMITATIONS AND DON T GO TOO FAR

10 Common Problems Margins Skin lesions including Moh s technique Head and neck tumours Ureteric margins in urothelial tumours Prostatic apical margins in radical prostatectomy Curative Brain tumour resections (!) Make sure you know exactly where the tissue is from and use ink carefully if the specimen has to be orientated

11 Common Problems - Staging Lymph node status (eg lung, colon, upper and lower GI tumours, breast) Sentinel lymph nodes (eg breast and melanoma) Frozen section may be requested especially if one stage reconstruction is being performed but not now regarded as standard practice

12 Common Problems - Artefacts Do not overmanipulate, compress fresh tissue or allow to dry Cells may be larger than in conventional sections Find an area of recognisable cells or structure and compare it to abnormal cells Make sure you have an adequate section which is representative Be prepared to seek more experienced or specialist advice if you have to

13 Specialist Areas - Parathyroid Is it a Parathyroid? - is it normal, hyperplastic or adenoma Need to know normal weights (up to 60mg per gland, mg for all four) Does the patient have renal failure? Is there a normal rim of parathyroid? (only if you are lucky) Is there fat admixed with the gland? (more common in hyperplasia and normal) What are the other glands like? you MUST ask

14 Specialist Areas - Lung Small Cell or non Small Cell Nuclear characteristics are the key small cells are larger than you think especially in frozen sections Primary or Secondary Adenocarcinoma Use cell morphology and compare to the original primary if it is available Consider intraoperative TTF1 (takes half an hour and only useful if positive)

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16 Specialist Areas - Lung TB or not TB? (That is the Question) It is inevitable that if you do lung work you will do a frozen section on active TB at some stage Do a risk assessment before you cut the case If you do still cut a case of TB the cryostat must be decontaminated. You must report this as a Clinical Incident

17 Specialist Areas - Lung Mediastinal Lymph nodes for staging prior to lung resection If they contain tumour then the patient is usually incurable surgically (at least pn2) Make sure you have sampled the whole node Check the original histological type for comparison if you have access to it

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19 Specialist Areas - Margins Moh s technique for skin tumours looks at the whole deep and lateral resection margin by flattening a disc of tissue deep to the resected lesion Technically difficult Not widely practiced as originally devised Multiple samples of edges of lesion more common in clinical practice in UK

20 Specialist Areas - Margins Margins of Head and Neck tumours may be particularly difficult Get surgeon to send small samples of the specific areas not the whole resection Compare to original tumour if possible Be aware of catches such as minor salivary glands or lymphoid aggregates that can mimic tumour Perineural invasion is always sinister Similar problems may occur in skin with sweat glands etc

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22 Specialist Areas - Margins Major resections for Urothelial tumours Urologists may ask for frozen sections of ureters or urethra to look for in situ or invasive tumour Involvement of margins may limit bladder or other urinary tract reconstruction (neobladders etc) Recent work indicates that ureteric positive margins for CIS may not matter

23 Specialist Areas - Margins Some surgeons ask for assessment of margins when performing radical prostatectomy for prostatic carcinoma Compressed prostate gland may mimic cancer

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25 Specialist Areas - Testis Most testicular resections for tumour are performed without preoperative biopsy following ultrasound assessment Small indeterminate lesions may require frozen section to allow partial orchidectomy Examples include scars (but beware regressed tumours), benign cysts, Leydig or Sertoli cell tumours, haemangiomas or adenomatoid tumours (usually epididymal) The question being asked is Germ cell tumour or not?

26 Testicular abscess Scarring and regressed seminoma

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28 Specialist Areas - Kidney Nephron sparing surgery (partial nephrectomy) has become more common in recent years Surgeons may wish for a frozen section of the parenchymal margin Beware artefacts caused by heat or RFA (Radiofrequency ablation)

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31 Specialist Areas - Thyroid Preoperative assessment and FNA should make Frozen sections a thing of the past No use in Follicular lesions May be helpful in assessment of lymph nodes in Papillary Carcinoma

32 Health and Safety Considerations What type of facility are you using - in operating theatre - within lab - Category 3 (able to deal with higher risk of infection etc with appropriate protocols

33 Specialist Areas GI Incidental liver lesions are common during GI surgery Possibilities include metastases, haemangiomas, focal nodular hyperplasia and bile duct hamartoma Intraoperative findings and comparison with the primary if available may help

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35 Frozen sections in the Mortuary Need to comply with Consent, Coroners Rules and HTA licence considerations May be useful but formal Histology is better in most cases Consider use of PM cytology as well but still need Consent/Coroner s permission

36 Risk Assessment - Infection High TB risk, known HIV, HEP B or C are contraindications to Frozen section, However if you do deal with an infected case you must know what to do. Incident reporting Closure and decontamination of facility Assessment of risk to self and staff

37 Risk Assessment Other issues Sentinel lymph nodes risk of radioactivity need a protocol and monitoring of radioactivity

38 Risk Assessment other infections MRSA, Norovirus, Clostridium difficile are not a frozen section contraindication even though they are regarded as a serious clinical risk to patients

39 Record Keeping Keep a written contemporaneous record of the name of the clinician you have spoken to including time and date. Record exactly what you have told the surgeon Transcribe this onto the final report Audit and assess any discrepancies in diagnosis between Frozen section and final diagnosis Inform the surgeon of any discrepancies that might affect management

40 Key Points Frozen Sections are for intraoperative management decision making Give as much detail as you can Don t defer unless you have to Don t go too far with unneccessary or irrelevant detail Ask for more information (or tissue) if you need to Remember that the surgeon is as stressed (or more so) than you are