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Vasculitis: Large, Medium, Small Vessel (MRCP Part 1)

TL;DR

Vasculitis is a high-yield, classification-driven topic in MRCP Part 1, where questions test your ability to distinguish large, medium, and small vessel syndromes using clinical patterns and antibody profiles. Mastering ANCA associations, organ involvement, and classic exam traps is essential. This guide provides a structured framework, mini-case practice, and a focused revision checklist.


Why this matters

Vasculitis questions in MRCP Part 1 are not about memorising obscure pathology slides. They test structured reasoning:

  • Can you classify by vessel size?

  • Can you map antibodies to diseases?

  • Can you recognise organ-system patterns?

  • Can you avoid common mimics?

The exam follows the Chapel Hill Consensus classification system (2012 update) (Watts et al., Arthritis & Rheumatism, 2013: https://pubmed.ncbi.nlm.nih.gov/24174329/). Understanding this framework simplifies the entire topic.

If you are building foundations, review the MRCP Part 1 overview first, then return here to consolidate vasculitis.


Classification Framework (Core Table You Must Know)

Vessel Size

Key Conditions

Classic Clue

Antibody

Large

Giant cell arteritis (GCA), Takayasu arteritis

Limb claudication, pulseless disease

None specific

Medium

Polyarteritis nodosa (PAN), Kawasaki disease

Renal infarcts (no GN), coronary aneurysm

HBV (PAN association)

Small (ANCA-associated)

GPA, MPA, EGPA

ENT + lung + kidney

PR3 or MPO

Small (immune complex)

IgA vasculitis, cryoglobulinaemia, anti-GBM

Palpable purpura, GN

IgA, cryoglobulins, anti-GBM

This classification answers a significant proportion of exam stems.


The 5 Most Tested Subtopics

1. Giant Cell Arteritis (GCA)

Guidelines from the British Society for Rheumatology emphasise urgent steroid treatment in suspected cases (https://academic.oup.com/rheumatology/article/59/3/e1/5687641).

High-yield associations:

  • Age >50

  • New temporal headache

  • Jaw claudication

  • Visual disturbance

  • Association with polymyalgia rheumatica

Exam pearl:Do not delay steroids for biopsy if vision is threatened.

2. Takayasu Arteritis

  • Young woman

  • Reduced or absent upper limb pulses

  • BP discrepancy

  • Subclavian stenosis

Classic phrase: “Pulseless disease.”EULAR overview: https://ard.bmj.com/content/78/1/19

3. Polyarteritis Nodosa (PAN)

Key features:

  • Medium vessel necrotising vasculitis

  • Renal infarction

  • Mononeuritis multiplex

  • Livedo reticularis

  • Association with hepatitis B

4. ANCA-Associated Vasculitis (AAV)

Extensively tested in MRCP.

EULAR recommendations (2022): https://ard.bmj.com/content/81/4/570

Granulomatosis with Polyangiitis (GPA)

  • ENT disease (chronic sinusitis, saddle nose)

  • Cavitating lung nodules

  • Rapidly progressive GN

  • PR3-ANCA (c-ANCA)

Microscopic Polyangiitis (MPA)

  • GN + pulmonary haemorrhage

  • No granulomas

  • MPO-ANCA (p-ANCA)

Eosinophilic Granulomatosis with Polyangiitis (EGPA)

  • Asthma

  • Eosinophilia

  • Neuropathy

  • Often MPO-ANCA

Asthma + eosinophilia = EGPA until proven otherwise.

5. Immune Complex Small Vessel Vasculitis

IgA Vasculitis

  • Palpable purpura

  • Abdominal pain

  • Arthralgia

  • IgA nephropathy

Cryoglobulinaemia

  • Associated with hepatitis C

  • Purpura + neuropathy + GN

  • Low complement levels

Anti-GBM Disease (Goodpasture’s)

  • Pulmonary haemorrhage

  • Rapidly progressive GN

  • Anti-GBM antibodies


Medical student revising vasculitis classification for MRCP Part 1 exam.

10 High-Yield Exam Points

  1. PAN does not cause glomerulonephritis.

  2. GPA = granulomas + PR3-ANCA.

  3. MPA = GN + pulmonary haemorrhage + MPO-ANCA.

  4. EGPA requires asthma history.

  5. GCA only in >50 years.

  6. Takayasu in young women.

  7. Cryoglobulinaemia → low complement.

  8. Anti-GBM = lung + kidney only.

  9. Endocarditis can produce ANCA positivity.

  10. Cholesterol emboli mimic vasculitis but show eosinophilia.

Reinforce these patterns using the Free MRCP MCQs section.


Mini-Case (MRCP Style)

A 61-year-old man presents with sinusitis, haemoptysis and rising creatinine. Urinalysis reveals red cell casts. CXR shows multiple cavitating nodules.

Most likely diagnosis?

Answer: Granulomatosis with polyangiitis.

Explanation: ENT involvement + lung cavitation + rapidly progressive GN = classic GPA triad.

If asthma and eosinophilia were present → think EGPA.If no ENT involvement → consider MPA or anti-GBM.

Practise under timed conditions with Start a mock test.


Five Common Exam Traps

  1. Confusing PAN with MPA

  2. Assuming all small vessel vasculitis are ANCA positive

  3. Ignoring age clues in GCA

  4. Missing hepatitis associations

  5. Over-relying on antibody tests instead of clinical pattern


Practical Study Checklist

Step 1 – Memorise the Classification Table

Rewrite it from memory daily for 7 days.

Step 2 – Antibody Mapping

Create a one-page sheet:

  • PR3 → GPA

  • MPO → MPA/EGPA

  • Anti-GBM → Goodpasture’s

Step 3 – Organ Triads

Practise recognising:

  • ENT + lung + kidney

  • Asthma + eosinophilia

  • Purpura + abdominal pain

Step 4 – Timed Practice

Use the Free MRCP MCQs bank regularly.

Step 5 – Review Errors

Categorise mistakes:

  • Misclassification

  • Antibody confusion

  • Missed systemic clue


FAQs

How is vasculitis classified in MRCP Part 1?

By vessel size: large, medium and small. Small vessel is divided into ANCA-associated and immune complex types.

What is the difference between GPA and MPA?

GPA has granulomas and ENT involvement; MPA does not. GPA is usually PR3-ANCA positive, MPA is MPO-ANCA positive.

Does PAN cause glomerulonephritis?

No. PAN affects medium vessels and causes renal infarction but spares glomeruli.

Which vasculitis is associated with asthma?

Eosinophilic granulomatosis with polyangiitis (EGPA).

Which infections are linked to vasculitis?

Hepatitis B is linked to PAN; hepatitis C to cryoglobulinaemic vasculitis.


Ready to start?

Mastering vasculitis requires classification clarity and repeated exposure to exam-style stems. Consolidate your preparation using the MRCP Part 1 overview and reinforce knowledge with the Free MRCP MCQs and Start a mock test today.


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