I. Where to Start – NUS Pathweb

What is a simple approach to describing gross pathology?

When faced with a pathology specimen, don't panic -> just be systematic.

There are 5 steps. Here's what to do: (click on each tab to expand)

1. Describe the ORGAN and the PLANE of sectioning

Planes:

Sagittal: Plane that runs down through the body, dividing the body into left and right portions. Subsections of the sagittal plane include:
- Midsagittal runs through the median plane and divides along the line of symmetry
- Parasagittal is parallel to midline but does not divide into equal left and right portions.
Coronal (frontal): Plane that runs perpendicular to the sagittal plane and divides the body into anterior and posterior (front and back) portions.
Transverse: Horizontal plane that divides the body into upper and lower portions; also called cross-section.

Transverse section of liver

Coronal section of brain

Sagittal section of knee

2. Describe the DISTRIBUTION of the abnormality: Localised vs Diffuse

- The differential diagnoses (DDx) are quite distinct:

Diffuse process: the pathology affects the whole organ uniformly
- Enlargement, change in colour, shrinkage/atrophy
- Eg, fatty change in the liver, chronic venous congestion in the lung, diffuse hyperplasia in the thyroid gland
- DDx à Metabolic diseases, autoimmune conditions, haemodynamic disorders, sometimes infections etc.
Localised/focal process – the pathology is seen as one or several discrete lesions, while the rest of the organ appears grossly normal.
- Mass, cyst, ulcer etc.
- DDx - Neoplasms, cysts, abscesses, infarctions etc.

3. State the NATURE and LOCATION of the abnormality

Nature: mass, nodule, cyst, cavity, scar, focus of discoloration, etc

For mucosal-lined organs eg, Gastrointestinal tract - ulcer, polyp, perforation etc.

“There is a nodule in the upper lobe of the right lung.”

Tip: Try to avoid the word “lesion” – this is entirely non-specific and non-descriptive.

"There is a wedge–shaped, well demarcated area of pallor within the renal cortex in the upper pole of the kidney.”

“The thyroid gland is diffusely enlarged and dark brownish in colour.”

4. Describe the CHARACTERISITICS of the abnormality

For localized lesions:

Location – eg. middle lobe of right lung; upper pole of right thyroid lobe, colonic mucosa, subcapsular region of kidney etc.
Size
Shape – rounded (eg. benign neoplasms), ovoid, irregular, wedge-shaped (eg. infarcts)
Number of lesions – solitary, multiple
Cut surface – texture (solid/cystic/friable), colour (tan, pale, blackish, greenish, variegated), presence of necrosis (paler areas) or haemorrhage
Edges of lesion
Solid lesion – well defined vs ill-defined, infiltrative, enc
Ulcer – regular, punched out, flat edges (favour benign) vs heaped edges, overhanging edges (favour malignant); describe base (necrotic; smooth; visible vessel etc.)

5. Describe any visible CAUSE or EFFECT/COMPLICATION of the disease

Exercise: Cause and effect – Below is a heart specimen with a myocardial infarct in the left ventricle. Look carefully = can you spot the cause – the occluded coronary artery (left anterior descending artery)? If not, check out the video below.

If you can't play the video, watch it here on YouTube: https://youtu.be/iU_CGNQj7lA

I. Where to Start?

II. Glossary of Terms

III. Approach to Gross Pathology: Practice!

IV. Approach to Gross Pathology: Quiz

Approach to Gross Pathology One Page Summary

Approach to Gross Pathology Chapter Home

Pathology Demystified

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