Can i perceive your question as related to the sensitivity and specificity of FNAC ?

In that case, FNAC can mislead. Clinical observation, multiple FNAC, history need to be correlated with the diagnosis. In case the clinical picture does not correlate with FNAC, biopsy need to be performed.

PPV and NPV of the diagnosing pathologist center, gold standard, stains employed, operator's experience also influence the outcome.

Kindly wait for a publication using Bayes concept in http://www.amhsr.org/aheadofprint.asp; letter to editor.....

Most patients with parotid masses require surgery and if a benign tumor is suspected, FNA can add little to change preoperative planning. If a patient has a lesion, based on clinical presentation or imaging, that may be suggestive of a malignancy (primary or metastatic) then FNA can be very helpful in preoperative planning by allowing the surgeon to consider adding ipsilateral neck dissection to the procedure and the patient can be counseled concerning the topic of potential sacrifice of a portion of the facial nerve if necessary for an appropriate oncologic resection. In patients that are higher risk for surgery (based on age or comorbidities), an FNA that is suggestive of a benign pathology, such as a Warthin's tumor, can allow for close clinical follow up that is selected patients.

In short, I don't do FNA in all of my parotid patients, but I do find it to be helpful in selected situations.

You can think about a patient for 24hr and then perform your surgery in 2hr, while not it may takes 24hr to perform a surgery... FNA increase your knowledge about patient's lesion, you can talk to the patient about postoperative complications easier, in the scenario of inflammatory lesions you can go on with complementary para clinical tests such as CXR or PPD +/- incisional biopsy, also you can use frozen section in combination with FNA that yields more data than each of them per se. Also patient's salivary gland lesion may be a metastatic one and... More important than these issues is planning for Limited parotidectomy or Enucleation resection of the lesion that needs a thorough work up such as FNA pre-operatively.

Regarding to the mentioned issues, I'm a FNA proponents ;)

FNAC is very helpful in diagnoses parotid lump as this could help in planning management .Good cytologist is essential in this .I know one of the cytologist diagnostic rate more than 95%,and this very helpful for us to plan next investigation and treatment.

But would a negative FNAC report (in bench pathology) rule out neoplastic lesion unless FNAC is USGuided or immunocytology is employed or advanced modalities engaged for diagnosis? Alternatively, Is a negative FNAC diagnosis 100% neoplasm free, given the complex cytological nature of salivary gland...

Frankly Dr Wein has answered this already. Patients with a clinical parotid mass need definitive diagnosis and unless you personally have a cytology service which approaches 100% sensitivity and specificity (in which case you are very unusual) after basic examination and work up to exclude non tumour inflamatory conditions you know you are dealing with a tumour which (except for confirmed Warthins) mandates diagnostic and terapeutic excision with preservation of the facial nerve. This is why Patey described superficial parotidectomy as "the grand biopsy". In relation to the argument over counselling for benign and malignant lesions in my experience malignancy is usually clinically obvious, an involved branch of VII will be sacrificied but there is no survival advantage to the sacrifice of a working facial nerve even in the prescence of established malignancy. FNA in my mind sits with USS (except FNA is painful - try it yourself before calmly advocating it routinely) a sometimes useful test to be used for specific indications not just because it is easy. And USS - this looks like a snowstorm on a dark night to me wheras an MRI or CT allows me to plan the operation at least to some degree.

"...try it yourself before calmly advocating it routinely..." , and, " ...an MRI or CT allows me to plan the operation at least some degree."

Definitely agree with your views. In my practice FNA (either US guided or standard technique) is not an integral part of surgical planning in patients with parotid masses.

In Parotid mass, History, clinical examinations and ultrasonography will help in diagnosis.. FNAC in the hands of an expert cytologist will definitely guide us especially when it a guided FNAC.. however there are circumstances when the cytology is inconclusive, surgery is the option, according to the extension of lesion

From what i've seen FNA can be useful but has a relatively high false negative rate for carcinoma. If suspicious clinically, it may be useful to perhaps plan on intraoperative frozens, consent patients for a possibly more extensive surgery and be prepared to undergo more extensive resection +/- neck dissection accordingly.

FNAC requires an expert cytologist to report it.who is experienced in it. Every pathologist would agree that cytology specimen reporting is a separate skill in itself. Even an expert histopathologist might struggle a bit with cytology specimen.

With no adjacent solid tissue interfaces ... the interpretation is highly dependent on the experience and accuracy of the cytopathologist.

Secondly, cytology smears still may have high false negative results as it might be possible that only normal cells were aspirated ... Tumor cells are interspersed by normal cells population too. If the specimen is from this region, the results may be unreliable.

As Biron pointed out earlier, clinical suspicion has a role to play. And for most part, it is always prudent to be prepared to do a more extensive surgery if required based on intra operative frozen reports.

Here I would like to point out a fact which was discussed with a senior experienced Pathologist who used to work in Tata Memorial Hospital (mumbai) :-

......, from a surgeon's point of view, the most important aspects that are required are 1. Benign / malignant nature of the lesion (FNAC and clinical suspicion gives an indication) 2. Extent (mostly known by the imaging)

The treatment modality for malignant lesions is similar or almost same for all malignant lesions ... (the type of malignancy does not modify the treatment protocol much!) So it is not right to demand that the cytopathologist give the exact sub type of the tumor based on FNAC or even FNAB which is part of a part of the lesion! Also, that diagnosis, unless it has a bearing on the treatment plan, has no relevance for the surgeon!

And also their report is based on what they see, if the sample is not representative of the lesion, it cannot be helped. We must remmeber all these factors whil doing any biopsy for any lesion for that matter.

On deeper thought, I could not agree less about this pathologist's opinion!

I am reminded here of a saying "The pathologist is the best critic of a surgeon" because it is he who tells us of our inadequate margins, positive margins and our mistakes in clinical judgement on the nature of the lesion or the extent of the lesion and our inadequate sampling in biopsy which gives inconclusive results at times and so on!

Regards,

Dr. Akilesh. R

FNAC is always helpful and we must keep in mind that every diagnostic procedure has its own limitations. Pathologist as an individual do the his/her best.