General pathology · The pathology laboratory

From specimen to report: fixation, margins and the pathology report !

Technique

The specimen travels from theatre to microscope in several steps; the final report gathers what is needed to stage and treat.

Updated 2026-11-01

What it is

The pathology report is the document that confirms a diagnosis and, in cancer, gives the data that decide treatment: type, grade, size, margins, invasion and lymph nodes. Its quality depends on every earlier step, from labelling and fixation to gross examination. An error at the start (an unfixed or mislabelled specimen) cannot be fixed at the end.

Key facts

Positive margin: tumour touches the ink; negative margin: it does not.
Cold ischaemia (time from removal to formalin) should be short: it alters hormone receptors and DNA.
Parts of the report: identification, gross description, microscopic description, diagnosis and comments.
The synoptic report (a structured checklist) prevents key items from being left out.
A report can be corrected by an addendum (new information) or an amendment (a change of diagnosis).

Step by step

Request with complete clinical data and a specimen labelled with two patient identifiers.
Immediate fixation in buffered formalin, in ample volume; delay degrades proteins and DNA.
Gross examination: the specimen is measured, described and its edges inked to recognise the margins.
Representative blocks are taken: tumour, closest margins and every lymph node.
Processing: dehydration, paraffin embedding, thin sections and H&E staining.
Microscopic study and, if needed, immunohistochemistry or molecular tests.
Structured report with diagnosis, prognostic factors and pathological stage (pT, pN).

What a cancer report contains and why it matters

Item	What it says	Why it matters
Histological type	Which tumour it is	Defines behaviour and treatment
Grade	How much it resembles normal tissue	Prognosis
Size and extent	Diameter and structures invaded	The pT category of the stage
Margins	Whether tumour is at the inked edge, or how far from it	Need for re-excision or radiotherapy
Lymphovascular and perineural invasion	Tumour inside vessels or around nerves	Risk of recurrence and metastasis
Lymph nodes	How many were examined and how many contain tumour	The pN category; in colon at least 12 are expected
Biomarkers	Receptors, HER2, DNA repair, mutations	Targeted treatment

Clinical notes

When the clinical picture and the report disagree, the right step is to talk to the pathologist and, if needed, ask for a second opinion.
In breast cancer, the receptor and HER2 status in the report decides systemic therapy.
A positive margin after breast-conserving surgery usually leads to re-excision.

Test yourself

Think of the answer, then tap the question to see it.

What does a positive margin mean in a pathology report?

That tumour cells lie at the inked edge of the specimen, so tumour was left at the limit of the resection.

Why are specimen edges painted with ink?

So the true cut surface can be recognised under the microscope and one can tell whether tumour reaches the margin.

What harm does delayed fixation cause?

Cold ischaemia degrades proteins and nucleic acids and can give false-negative hormone receptor and molecular results.

What is the pTNM stage based on?

On examination of the surgical specimen: tumour size and extent, involved lymph nodes and, if proven, metastases.

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: Pathology Reports (National Cancer Institute, 2023); How Cancer Is Diagnosed (National Cancer Institute, 2023).

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Representative model, for educational purposes only.