A non-diagnostic specimen is a difficult thing for everyone to deal with. Patients endure the FNA procedure in hopes that they will get a diagnosis. They rearrange their schedules, take off from work or school, which costs both time and money. Referring doctors send patients for FNA procedures because a correct and rapid diagnosis leads to efficient and appropriate treatment. When a specimen is non-diagnostic, everyone’s time is wasted and no one gets the answers that are sought.
Nobody likes non-diagnostic specimens. But, let’s look at this a little more closely.
We start with the imaging. Imaging can give us an idea of the quality of the lesion to be aspirated. Many patients come to me with imaging reports or CDs documenting studies that they have had before they arrive at my door, but I always perform an ultrasound to see for myself what is going on. There are many things that we can tell by looking with ultrasound. We can see if the lesion is encapsulated or not, and if there is a difference in the echogenicity of the lesion compared with the surrounding normal tissue. We can also see what the inside of the lesion looks like – if it is cystic, solid, or if it has calcifications or other distinctive characteristics that ultrasound can detect. If it is a lymph node, we can see if it has the characteristics of a benign lymph node or if these characteristics are absent, making it more suspicious. All of these things happen prior to inserting a needle into the lesion.
Depending on the time interval between the initial imaging and the patient’s appointment, what we see on ultrasound can be different from the original study. If the patient has been treated with antibiotics or if they have been undergoing chemotherapy or radiation therapy, the picture can change. A lesion might have decreased in size or might not even be seen on ultrasound. Or, depending on the original modality, the lesion will not have the same appearance or may not even be seen on ultrasound.
The point is this: knowing what is being aspirated makes a difference in the interpretation in many cases. The only way for the pathologist to know this is either to perform the ultrasound herself or be present in the room when the ultrasound is being performed.
Real time evaluation of the specimen also helps with decreasing the non-diagnostic rate. A practitioner who evaluates the specimen on-site in real time can determine whether or not the specimen will yield a diagnosis. It is much easier to take a few more samples while the patient is still on the table than to have to call the patient back after they have left the office. Sometimes it is a matter of repositioning the patient to have better access, and that will do the trick to get a diagnostic sample. Patients are also more likely to be understanding and allow the practitioner to get more sample if they are aware that there is a slim chance this will happen, so I always inform my patients that this event may occur. In my experience, however, patients should not undergo more than a second round of sampling, even if the second round is still unsatisfactory. Although a rare occurrence, sticking patients over an over again does not have a good outcome for either the patient or the practitioner and only leads to frustration for both parties.
Rarely, after exhausting all reasons and explanations, the specimen still turns out to be non-diagnostic. Why would this happen? It could be the nature of the lesion itself – it could be fibrous or acellular; it could be fatty and not yield cells; it could be a tumor of neural origin, which can be paucicellular. In a patient that has been radiated it could be fibrosis or scar formation. It could be a cartilaginous or bony lesion. There are those rare occasions where we do not get an answer despite our best efforts, and it is in those rare occasions that we are reminded of the limitations to this test in even the best of all possible clinical circumstances.
The final point to remember is that when a diagnosis of “non-diagnostic” is made, it is important for the patient and their physician to follow up with radiologic surveillance and possible repeat FNA or excisional biopsy in the future, so that a diagnosis is not missed.