Makindo Medical Notes

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🧠 About

• Cutaneous small vessel vasculitis (CSVV), also called leukocytoclastic vasculitis, is the commonest form of vasculitis affecting the skin.
• It represents inflammation of dermal capillaries, venules, and arterioles leading to palpable purpura and, occasionally, ulceration or necrosis.
• It may be idiopathic or secondary to infection, drugs, autoimmune disease, or malignancy.

🧬 Aetiology & Pathophysiology

• Driven by immune complex deposition in post-capillary venules → complement activation → neutrophil infiltration and fibrinoid necrosis of vessel walls.
• Commonly associated with hypersensitivity reactions, infections, and autoimmune disorders.
• Histopathology shows: neutrophilic infiltrate, nuclear debris (leukocytoclasia), and fibrin deposition.

🎨 Clinical Features

• 🌸 Palpable purpura: non-blanching, raised purplish lesions, often on lower legs (gravity-dependent areas).
• Lesions may bleed, blister, ulcerate, or form necrotic plaques.
• May be associated with burning, pain, or pruritus.
• Livedo reticularis or petechial rash may coexist in chronic or recurrent cases.
• Systemic symptoms (arthralgia, abdominal pain, haematuria) may suggest systemic vasculitis.

🔍 Differential Diagnosis

• Thrombocytopenia or coagulopathy (non-palpable purpura).
• Scurvy (perifollicular haemorrhage).
• Meningococcaemia or rickettsial infections (febrile purpura).
• Drug eruptions and septic emboli.

⚗️ Common Causes

• 💊 Drugs: β-lactam antibiotics, thiazides, NSAIDs, allopurinol.
• 🦠 Infections: Streptococcus (ASO positive), Hepatitis B/C, HIV, Neisseria, Rickettsia, Meningococcus.
• 🧩 Autoimmune/Rheumatology: RA, SLE, Sjögren’s, Sarcoidosis.
• 🦠 Inflammatory Bowel Disease: Crohn’s, Ulcerative colitis.
• 🧫 Malignancy-associated: particularly haematological cancers (e.g. lymphoma).

🧪 Investigations

• Basic Screen: FBC, ESR/CRP, U&E, LFTs, urine dipstick for haematuria/proteinuria.
• Immunology: ANA, dsDNA, ENA, ANCA, complement (C3, C4), cryoglobulins.
• Infectious screen: Hepatitis B/C serology, HIV test, ASO titres, blood cultures.
• Systemic assessment: ACE level (sarcoidosis), serum electrophoresis, CXR.
• Diagnostic biopsy: – Fibrinoid necrosis of dermal vessels – Neutrophilic infiltrate with nuclear debris (leukocytoclasia) – Extravasation of erythrocytes into dermis.

💊 Management

• 🎯 Treat underlying cause: Discontinue offending drug, treat infection or autoimmune disease.
• 🧍‍♀️ Supportive: Rest, leg elevation, compression stockings, emollients.
• 💊 Pharmacological: – Mild: NSAIDs or antihistamines for symptomatic relief. – Moderate: Colchicine or Dapsone (reduce neutrophil activation). – Severe or systemic: Short course of oral corticosteroids (e.g. prednisolone 20–40 mg/day taper). – Refractory: Immunosuppressants (azathioprine, methotrexate, or mycophenolate) under specialist care.
• 🩺 Monitor for renal, GI, or neurological involvement (suggests systemic disease).

📊 Prognosis

• Most idiopathic or drug-induced cases resolve within 4–6 weeks.
• Recurrence may occur if the trigger persists or in autoimmune disease.
• Chronic or ulcerating forms require multidisciplinary input (dermatology, rheumatology).

💡 Teaching Tip

• Always differentiate between cutaneous-only vs systemic vasculitis — systemic cases need urgent evaluation for renal or pulmonary involvement.
• Histology confirms the diagnosis — biopsy new lesions (24–48 hrs old) for the best yield.
• In teaching, contrast this with Henoch–Schönlein Purpura (IgA vasculitis) — identical pathology, but with systemic IgA deposition (esp. renal).

📚 References

• BNF: Systemic Corticosteroids & Immunomodulators
• Jennette JC et al., Arthritis Rheum 2013;65:1–11 — Chapel Hill Consensus Classification.
• Genta RM, Mod Pathol 1990;3(3):282–296 — Cutaneous small vessel vasculitis histology.
• DermNet NZ: Leukocytoclastic Vasculitis (2023).