When a patient is awaiting a diagnosis, every detail matters. Beyond visible tests or medical examinations, there exists a meticulous analysis carried out in the laboratory that makes the difference between uncertainty and clarity. Understanding how cells and tissues are studied helps one appreciate the importance of specialist areas such as histopathology and cytodiagnosis.
At Ambar Lab we work with a catalogue of more than 3,000 laboratory tests, with the aim of supporting healthcare professionals and patients in making evidence-based clinical decisions. In addition to carrying out tests, we offer support with project management and collaboration on new initiatives, with a catalogue where the availability of tests and their associated information can be consulted.
In this article, we explain what histopathology and cytodiagnosis encompass, how a sample is processed, which techniques are used, and why these areas are so relevant both in clinical practice and in the laboratory setting.
What are histopathology and cytodiagnosis?
Histopathology and cytodiagnosis are the areas of the laboratory that study diseases through the analysis of tissues (histopathology) and cells (cytology). Their value lies in allowing the observation of structural and cellular changes that explain symptoms, confirm suspicions, and guide medical decisions. That is to say:
- Histopathology: focuses on tissues obtained from biopsies, surgical specimens, or organ samples.
- Cytodiagnosis: evaluates individual cells or small clusters, obtained from fluids, scrapings, or aspirations.
This combination, histopathology and cytodiagnosis, is key in a wide variety of situations: identifying benign or malignant lesions, assessing inflammatory or infectious processes, and supporting the monitoring of treatments where serial follow-up is required.
Differences between histopathology and cytology
Within histopathology and cytodiagnosis, histology and cytology do not compete: they complement one another.
Histopathology: tissue architecture
Histopathology allows us to see the “map” of the tissue: how cells are organised, how a lesion invades surrounding structures, what relationship it has with neighbouring tissues, and what overall pattern it presents. It is useful when the distribution, surgical margins, or degree of involvement are of particular importance.
Cytodiagnosis: cellular detail with minimal invasiveness
Cytodiagnosis tends to be less invasive and more efficient in many cases, as it works with cells obtained through techniques such as fine-needle aspiration or fluid cytology. Its value is high when a preliminary orientation is needed or when tissue sampling is technically complex.
How a sample is prepared in histopathology and cytodiagnosis
A decisive part of histopathology and cytodiagnosis takes place before the microscope. The pre-analytical phase and the processing stage determine the quality of the result.
Reception and registration
Upon reception, the identification, sample type, container, fixative (where applicable), and available clinical data are verified. Traceability is essential to ensure that the final report is both useful and reliable.
Fixation and preservation
In histology, fixation prevents tissue degradation and preserves structures. In cytology, the method of preservation may vary depending on whether the preparation involves a smear, liquid-based cytology, or another method.
Embedding, sectioning, and slide preparation
For tissue samples, after processing, a block (usually paraffin) is obtained and very thin sections are cut for mounting on slides. In cytology, smears or cellular concentrates are prepared for staining and reading.
Common techniques: from classical staining to advanced methods
Histopathology and cytodiagnosis combines classical techniques with more advanced ones, depending on the clinical question.
Routine staining
General stains allow the visualisation of morphology, nuclei, cytoplasm, and tissue organisation. They form the basis of much of the diagnostic process.
Special staining
When certain deposits, micro-organisms, or specific components are suspected, targeted stains are employed to provide additional information.
Immunohistochemistry and immunocytochemistry
These techniques use antibodies to detect specific proteins in tissues or cells. They are ideal for classifying tumours, identifying the origin of a lesion, and supporting clinical decisions when morphology alone is insufficient.
Molecular pathology as a complementary tool
In certain situations, morphological findings are complemented by molecular biology techniques to detect genetic alterations or clinically relevant markers. In modern practice, this intersection between morphology and biomarkers has become a routine part of work in histopathology and cytodiagnosis.
How long does a histopathology and cytodiagnosis result take?
Turnaround times can vary considerably, as there is no single type of study. In histopathology and cytodiagnosis, the timeframe depends above all on the complexity of the sample and on whether additional techniques are required beyond the initial assessment.
Factors affecting turnaround time
- Type of sample: a straightforward cytology generally requires fewer steps than a biopsy with full processing.
- Quantity and size of material: a surgical specimen or multiple fragments require more time for preparation and review.
- Need for complementary techniques: if immunohistochemistry, special staining, or other ancillary tests are required, the report is delayed because each technique adds laboratory processing and reading stages.
- Sample quality and clinical data: when the material arrives with artefacts, is poorly representative, or lacks relevant clinical information, it may be necessary to cut additional sections, request more data, or even obtain a new sample.
- Workflow at the centre: the working processes (transport, registration, prioritisation by clinical urgency, etc.) also affect the timeframe.
In practice, many reports are issued within relatively short timeframes when the case is straightforward, but the time increases when the pathologist needs to confirm a diagnosis using additional techniques or when the sample requires a more extensive study. For this reason, the actual turnaround time is always better understood when one knows exactly which study has been requested and whether a complementary analysis is planned.
How a biopsy is processed in histopathology and cytodiagnosis: step by step
The processing of a biopsy is a chain of work in which each step prepares the tissue so that it can be evaluated under the microscope with the greatest possible clarity. Within histopathology and cytodiagnosis, this workflow is what transforms a biological sample into a useful clinical report.
1) Reception, identification, and registration
The sample is received, its identification is verified, and it is registered in the system to ensure traceability. The type of container and the general condition of the material are also reviewed at this stage.
2) Tissue fixation
Fixation preserves the tissue and prevents degradation. It is a critical step because it determines the quality of the section and the subsequent reading.
3) Macroscopy (description and selection of fragments)
Prior to microscopic examination, a macroscopic assessment is performed: the sample is described (size, appearance, number of fragments) and the areas to be processed and studied are selected.
4) Processing and embedding
The tissue undergoes technical processing to be prepared for sectioning. It is then embedded in a solid support (usually a paraffin block), which allows thin, uniform sections to be obtained.
5) Sectioning and slide mounting
Very thin sections are cut from the block and mounted on slides (the “glass slides” examined under the microscope). If needed, multiple levels of sectioning are prepared to expand the available information.
6) Staining
Routine stains are applied to visualise cellular and tissue structures. If required by the case, special stains are added to identify specific elements.
7) Microscopic reading and interpretation
The specialist evaluates the tissue architecture, cellular features, and overall pattern. At this stage, differential diagnoses are considered if there is reasonable uncertainty.
8) Complementary techniques (if required)
When morphology alone is insufficient to confirm the diagnosis, techniques such as immunohistochemistry or other ancillary tests are requested, to assist in classifying findings more accurately and completing the report.
9) Report drafting and validation
The report is drafted with the findings and the diagnostic conclusion. In some centres or for certain cases, there may be additional internal reviews before validation.
10) Issuing the result and communicating it through the care pathway
The result is issued through the established pathway (requesting centre, specialist, hospital system, etc.) to maintain the traceability of the entire process.
When histopathology and cytodiagnosis are requested
Without going into particular cases, there are common scenarios in which this type of study is requested:
- When a lesion is detected and needs to be characterised
- After a surgical intervention, to assess what has been removed
- When clarification of the origin of certain clinical findings is required
- In the analysis of biological fluids when relevant cellular information is sought
In all of these, histopathology and cytodiagnosis provide a perspective that no other test can replace: the direct reading of cellular and tissue changes.
Quality, traceability, and communication of results
In the laboratory, quality is not limited to instrumentation. In histopathology and cytodiagnosis it encompasses:
- Correct identification of the sample
- Adequate fixation and processing times
- Correct preparation of slides
- Reading criteria, review processes, and report consistency
- Internal traceability to allow auditing of each step
A good diagnosis begins with a good sample
A good result does not depend solely on the final analysis, but on everything that happens from the very first moment: the correct identification of the sample, its preservation, laboratory processing, and the selection of appropriate techniques. When each step is carried out with rigour, the report provides a solid foundation for healthcare professionals to make decisions with confidence, and for patients to better understand the process.
If you would like to learn more about how we work at Ambar Lab, you can browse our test catalogue and discover which studies are available. You can also contact our team to discuss your analytical needs, whether you are a healthcare centre, a laboratory, or a private individual. We are here to help!
