How is histology different from cytology?

Diagnosis

The General Hospital (AKH) Vienna acts as the central hospital and is one of the largest hospitals in the world. A large number of diagnostic procedures are used at our institute:


histology

The institute is responsible for carrying out the entire range of histological-pathological examinations with the exception of neuropathology and a large part of dermatopathology. In addition to equivalent examinations of pathological institutes in other hospitals, there are special qualitative and quantitative requirements due to the central hospital function of the Vienna General Hospital, e.g. in the fields of transplantation and kidney pathology. Due to the high level of training of the employees and the good technical facilities in many areas, the institute acts as a central reference point for complex investigations and is therefore often consulted by external senders.

The level of training of the employees is kept at a high level through in-house training events, congress visits and participation in quality standard groups. Activities such as participation in the British quality assurance circle in the field of renal pathology (EQA (External Quality Assessement), organized by the University of Leicester and participation in the NEQUAS international quality circle for Her 2 / neu diagnostics are examples of initiatives in the field of quality management and fuse.

The individual working groups maintain close cooperation with the clinical departments and conduct routine case discussions with clinicians.

The general histopathological diagnosis is carried out in a time-focused form in teams consisting of specialists and doctors in training according to a rotation mode. Complicated cases that require further investigation are forwarded to members of the respective specialized working groups.


Molecular pathological investigations

The development of molecular pathological methods, the molecular analysis of tissue and cytological material is rapidly developing and accordingly the development of a molecular pathological working group is being advanced with high priority.

In diagnostic molecular pathology, all those methods are used which are based on the detection and examination of DNA and RNA from tissues and body fluids.
The most important area of ​​application within the framework of a modern, clinically oriented pathology is on the one hand the detection of changes in certain tumor genes (oncogenes, suppressor genes) and on the other hand the detection of pathogen-specific DNA / RNA for the diagnosis of infectious diseases.

At the institute, the entire spectrum of molecular pathology is used in diagnostics: In addition to Sanger sequencing, various PCR methods, arrays and FISH examinations, methods of “Next Generation Sequencing NGS” are increasingly being used.

Both panel sequencing and whole-exome sequencing are carried out here.


cytology

In contrast to histological examination material, cytological examination material consists of individual cells or small cell associations that have been detached from their tissues. Similar to how the clinician obtains tissue samples for diagnostic purposes from specific body regions or organs when performing biopsies on living patients, he can also remove cellular material and send it to the pathology department for cytological diagnostics. The cytological examination spectrum is almost as wide as that of the biopsies, i.e. cell material can be taken from numerous body regions and organs. In quantitative terms, the smear cytology of the cervix is ​​in the foreground for the early detection of cervical cancer (cervical cancer), but other material such as sputum, bronchial secretions, urine, effusion fluid (pleural effusion, ascites) and aspirates from various organs such as thyroid and lymph nodes are often examined cytologically. A distinction is made between puncture and smear cytology based on the type of material that is most frequently obtained.

Compared to the histological examination of biopsies, cytology has advantages in obtaining material, which - as it is predominantly bloodless and painless - does not or only slightly affects the patient. On the other hand, the main disadvantage is the limitation of the assessment to cytological criteria (properties of single cells), i.e. histological features such as tissue structure and its destruction by tumor invasion are not diagnostically available. This not only requires more concentration when examining the microscope, but also limits the diagnostic significance, so that it is not uncommon for dubious cytological findings to be checked histologically by biopsy.