What does a pathologist examine?

Written by: Dr Ashish Chandra
Published: | Updated: 20/02/2020
Edited by: Laura Burgess

A pathologist examines cells, tissues and body fluid with the use of a microscope or with other diagnostic tools. Have you been referred to a pathologist and wondered what they will analyse, how they do it and why? Dr Ashish Chandra explains exactly what he does as a pathologist, who specialises in histopathology, cytology and fine needle aspiration.

Pathologies: what's the difference between histopathology and cytopathology?

My job involves making a diagnosis and checking for infection, disease, cancer or precancerous conditions, by looking down the microscope at tissues or cells. When I make a diagnosis on tissues, this is called histopathology and in particular, I have considerable experience in urological histopathology which involves diseases of the kidney, the bladder, the prostate or the testes.

Cytopathology is the study of cells and making a diagnosis on the basis of the cellular appearances of an organ or a tissue under the microscope. This can be done in one of many ways. I could be sent some slides to review either histopathology or cytopathology, which may have been taken at another pathology lab at another hospital. These could simply be sent across to me and I would provide a second opinion for your physician and be available to discuss the results with them if they wish to do so.


When would I need fine needle aspiration (FNA)?

I also perform fine needle aspiration, which is a diagnostic procedure where I would examine and look at where small lumps were felt in the neck or any other parts of the body. A physician may have referred you to me if they found lumps whilst examining you and would like a needle test to be performed to ascertain the nature of that lump.


This procedure involves the use of a very small and very fine needle, for which no local anaesthetic is necessary although a cream or an ointment is available to apply before the procedure so that the skin is numb. The needle pinprick is not felt quite as much.

Alternatively, I may call upon the assistance of my radiologist colleagues if the lump is very small or difficult to feel. This may involve the use of actually injecting a local anaesthetic into the skin provided you’re not allergic to it and have not had any reactions in the past.

This allows us to take multiple samples, very small samples, using either a fine needle or a core biopsy needle. This would be examined either on the spot or taken back to the laboratory for additional tests to be performed. I would provide you with an assessment of the adequacy of the sample on the spot and let you know whether enough cells have been collected for an adequate diagnosis and for the tests to be performed.

What other methods does a pathologist use?

The additional tests that sometimes need to be performed are flow cytometry, which is a laser-based technology used if a lymphoma is suspected, or immunochemistry to ascertain the origin of a tumour or genetic and molecular tests on a range of tumours.


If you think you need a consultation with a pathologist for either cytology, fine needle aspiration cytology or histological pathology involving the kidney, bladder, prostate or testes, then please book an appointment to see me.

By Dr Ashish Chandra

Dr Ashish Chandra is a leading consultant histopathologist and cytopathologist based at Guy’s and St Thomas’ NHS Foundation Trust, London. He also sees patients on the private sector (Hospitals Corporation of America International (UK) or HCA) for performing fine needle aspiration (FNA). He also offers consultation on slides or blocks of tissue sent from other hospitals and laboratories for an expert opinion. He performs onsite evaluation of FNA samples taken by radiologists or physicians at endoscopic procedures such as EBUS and EUS.

Dr Chandra is available to perform FNA at HCA clinics including those at the Shard, London Bridge Hospital, Harley Street Clinic, the Platinum Medical Centre and the Wellington Hospitals. Dr Chandra was the Clinical Lead of the department at Guy’s and St Thomas’ (2009-12). He continues to be the Lead Consultant for Cytopathology and Urological histopathology.

Dr Chandra is an examiner for the RCPath and organises courses for the British Association of Urological Pathologists (BAUP), the British Association for Cytopathology (BAC) and the RCPath. He is an enthusiastic teacher and presents workshops and lectures at Cytology Training Centres in the UK and at international conferences. He has co-authored scientific papers, book chapters and is deputy editor of the journal, Cytopathology.

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