Churg strauss syndrome full details for md exams 15marks answer from fishman and murray only

Reading File

Finding Sources

Reading File

Loading Image

I now have all the material needed for a comprehensive 15-mark MD exam answer. Here is the full structured answer from Fishman's and Murray & Nadel's:

Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss Syndrome) - 15 Marks

1. Introduction and Nomenclature

Churg-Strauss Syndrome (CSS) was originally described in 1951 by Jacob Churg and Lotte Strauss as "allergic granulomatosis, allergic angiitis and periarteritis nodosa," based largely on autopsy findings. The authors recognized the allergic background, blood and tissue eosinophilia with granulomatous inflammation leading to necrosis, and vasculitis - the final outcome of the disease before any mitigating therapy was available.

At the 2012 Chapel Hill Consensus Conference on Nomenclature of the Vasculitides, it was renamed Eosinophilic Granulomatosis with Polyangiitis (EGPA) - a name intended to reflect the most prevalent pathology, the pathogenic role of eosinophils, and its similarities to the vasculitis shared with Granulomatosis with Polyangiitis (GPA) and Microscopic Polyangiitis (MPA).

Fishman's Pulmonary Diseases and Disorders, 2-Volume Set (block 15)

Murray & Nadel's Textbook of Respiratory Medicine (Ch. 96)

2. Definition

EGPA is a rare, systemic small-vessel vasculitis associated with:

A prominent allergic component
Asthma
Blood and tissue eosinophilia
Eosinophil-rich and granulomatous inflammation involving the respiratory tract
Necrotizing small- to medium-vessel vasculitis

It involves capillaries, venules, and arterioles. Granulomas, eosinophils, and palisading histiocytes in extravascular tissues are hallmarks that distinguish EGPA from other vasculitides.

Incidence: Annual incidence estimated at 0.6 to 6.8 cases per million.

Fishman's Pulmonary Diseases and Disorders (block 13)

3. Classification

EGPA is classified among the ANCA-Associated Vasculitides (AAV) because of similarities of the small-vessel vasculitis, even though only 30-70% of patients with active EGPA are ANCA positive. In most cases circulating ANCAs are absent, and robust criteria of documented systemic vasculitis are not always present.

Murray & Nadel's (Ch. 96)

4. Epidemiology

Predominates in the fourth or fifth decade of life
No gender predominance (contrasts with allergic asthma, which predominates in women and presents earlier)
Presents earlier in life than other ANCA-associated vasculitides
Occasionally reported in children and adolescents

Murray & Nadel's (Ch. 96)

5. Pathology

Because diagnosis is now made earlier, lung biopsy is seldom necessary and patients may receive corticosteroids before overt vasculitis has developed.

Classic pathologic features (on biopsy):

Feature	Description
Vasculitis	Necrotizing or non-necrotizing, involving mainly medium-sized pulmonary arteries; also capillaries (capillaritis)
Extravascular granuloma	Palisading histiocytes and giant cells - the "allergic granuloma"
Eosinophilic infiltration	Perivascular eosinophils in the early (prevasculitic) phase; diffuse tissue eosinophilia
Eosinophilic pneumonia	Similar to idiopathic chronic eosinophilic pneumonia when present
Diffuse alveolar hemorrhage	With capillaritis (rare)

Note: The pathologic lesions only rarely comprise all characteristic features on a single biopsy from one organ.

Murray & Nadel's (Ch. 96, Fig. 96.5)

6. Three Classic Phases

Three distinct phases have been described, though they are not seen in all patients, do not necessarily occur in this order, and may coincide:

Phase 1 - Prodromal Allergic Phase

Atopy, allergic rhinitis, sinusitis (with or without nasal polyposis), asthma
May last several years (mean: asthma precedes vasculitis by 3-9 years; range 0-61 years)
Asthma is generally severe and corticosteroid-dependent, presenting at a mean age of ~35 years

Phase 2 - Eosinophilic Phase

Prominent peripheral blood and tissue eosinophilia
Manifestations may remit and recur over this time period
Differential: parasitic infection, chronic eosinophilic pneumonia, hypereosinophilic syndrome

Phase 3 - Vasculitic Phase

Systemic vasculitis; may be life-threatening
Constitutional symptoms (asthenia, weight loss, fever, arthralgias, myalgias) herald extrapulmonary vasculitis

Fishman's Pulmonary Diseases and Disorders (block 15); Murray & Nadel's (Ch. 96)

7. Clinical Features

A. Pulmonary

Asthma present in 96-100% of cases - this is the single most constant feature
Focal infiltrates on chest radiograph in 30-70% of cases
Parenchymal involvement (alveolar infiltrates or nodules) in 38%
Transient, migratory alveolar-type infiltrates with predominantly peripheral distribution - indistinguishable from chronic eosinophilic pneumonia (most common finding)
Occasionally nodular lesions
Pleural effusions in ~10%
Diffuse Alveolar Hemorrhage (DAH): exceedingly rare in EGPA (in contrast to GPA and MPA)
In contrast to GPA, no destructive upper airway lesions or nasal septal perforation

Chest radiograph showing patchy bilateral infiltrates in EGPA - Nonspecific gnomonic infiltrates

Fig. 74-17A (Fishman's): Chest radiograph of patient with EGPA showing patchy peripheral infiltrates

B. Upper Airway

Chronic rhinitis in ~75% of cases
Relapsing paranasal sinusitis, nasal polyposis with eosinophilic infiltration on histopathology
Crusty rhinitis may be present, but much less severe than GPA
Mild-to-moderate hearing impairment is frequent

C. Cardiac (16-56%)

Most feared complication; may be severe and lead to cardiac failure, sudden death
Primarily due to eosinophilic myocarditis (most common); less commonly from coronary arteritis or endomyocarditis
Often insidious and asymptomatic - may be recognized only when left ventricular failure/dilated cardiomyopathy has developed
Can require heart transplantation
Conduction abnormalities, systolic or diastolic dysfunction, intracavitary thrombus, pericarditis
Every suspected EGPA patient must have ECG, echocardiography, and serum troponin I + NT-proBNP
Cardiac MRI (late gadolinium enhancement) is the preferred method to confirm involvement

D. Neurological (63-93%)

Mononeuritis multiplex is the most frequent form of peripheral nerve involvement - more frequent than in GPA/MPA
Can result from vasculitis of the vasa nervorum

E. Skin (50-78%)

Palpable purpura, subcutaneous nodules, urticarial lesions

F. Renal (16-49%)

Less prominent than in GPA and MPA
Does not generally lead to renal failure (in contrast to GPA/MPA)
Glomerulonephritis less common

G. Gastrointestinal (17-58%)

Eosinophilic gastroenteritis, perforation, ischemia, bleeding

Fishman's Pulmonary Diseases and Disorders (blocks 13 and 15); Murray & Nadel's (Ch. 96)

8. Laboratory Findings

Parameter	Finding
ESR, CRP	Elevated in >80% during acute phase/exacerbations
Blood eosinophil count	Elevated in >80% during active disease; absolute count typically >1500/μL
ANCA	p-ANCA (MPO-ANCA) in 30-70%
BAL	Eosinophilia

ANCA Clinical Phenotyping:

ANCA-positive subset: Higher incidence of renal involvement, DAH, glomerulonephritis, cutaneous vasculitis - shares features with GPA and MPA
ANCA-negative subset: Features overlap with hypereosinophilic syndrome - cardiac manifestations, migratory lung opacities (eosinophilic pneumonia) predominate; these two subgroups may have differing genetic predispositions

Fishman's Pulmonary Diseases and Disorders (block 13); Murray & Nadel's (Chs. 87 and 96)

9. Diagnosis

ACR/EMA Classification Criteria (1990 ACR - widely used):

Asthma
Eosinophilia >10% on peripheral blood differential
Mononeuropathy or polyneuropathy
Non-fixed pulmonary infiltrates
Paranasal sinus abnormality
Biopsy containing a blood vessel with extravascular eosinophils

Presence of 4 or more criteria yields sensitivity of 85% and specificity of 99.7%.

Tissue biopsy showing characteristic features (extravascular granuloma, vasculitis, eosinophilic infiltration) is definitive but not always required in typical cases.

Fishman's Pulmonary Diseases and Disorders (block 15)

10. Differential Diagnosis

Hypereosinophilic syndrome
Idiopathic chronic eosinophilic pneumonia
GPA (Granulomatosis with Polyangiitis)
Microscopic Polyangiitis
Allergic bronchopulmonary aspergillosis (ABPA)
Parasitic infections
Drug-induced eosinophilic syndromes
Polyarteritis nodosa

Distinguishing EGPA from these: presence of ANCA, serology for Aspergillus, finding of vasculitis + granulomas on biopsy, and molecular biologic analysis (in cases of idiopathic hypereosinophilic syndrome).

Murray & Nadel's (Ch. 96)

11. Prognosis - Five Factor Score (FFS)

The French Vasculitis Study Group validated the Five-Factor Score (FFS) for EGPA:

Factor	Score
Renal insufficiency (creatinine >150 µmol/L or proteinuria >1g/day)	+1
Clinically significant gastrointestinal disease	+1
Cardiac symptoms/cardiomyopathy	+1
Absence of upper airway (ENT) involvement	+1
Age ≥65 years	+1

5-year mortality rates:

FFS = 0: 9%
FFS = 1: 21%
FFS ≥ 2: 40%

Additional predictors of poor prognosis: severe alveolar hemorrhage, eye involvement (scleritis), fulminant mononeuritis multiplex.

Murray & Nadel's (Ch. 87); Fishman's Pulmonary Diseases and Disorders (block 15)

12. Treatment

A. Glucocorticoids (First Line - All Patients)

Mainstay of therapy; control disease in the majority of cases (>80-90%)
Oral prednisone 1 mg/kg/day for 3-4 weeks, then tapered to 5-10 mg/day by 12 months
IV methylprednisolone bolus (15 mg/kg/day for 1-3 days) for severe cases especially myocardial involvement
Prolonged low-dose steroids are often required for long-term control

B. Cyclophosphamide (for Severe/Organ-Threatening Disease)

Preferred agent for: FFS ≥ 2, cardiac involvement, GI involvement, CNS involvement, mononeuritis multiplex, DAH, ANCA-positive patients
IV cyclophosphamide: 0.6 g/m² at days 1, 15, 30; then 0.7 g/m² every 3 weeks (3 more infusions)
Reduces to 500 mg fixed-dose pulses every 2-3 weeks in patients >65 years
Associated with improved survival in severe EGPA with higher FFS
Should be replaced by azathioprine for maintenance after remission is achieved at 4-6 months

C. Remission Maintenance (18-24 months)

Azathioprine (preferred)
Methotrexate (0.25 mg/kg/week) - alternative to azathioprine
Mycophenolate mofetil - may be less effective than azathioprine for preventing relapses
In patients with no poor prognostic criteria: glucocorticoids alone may suffice for maintenance

Glucocorticoid-sparing agents (non-severe disease or inability to taper steroids below 10 mg/day):

Azathioprine, methotrexate, or mycophenolate mofetil

D. Biologic Therapy - Mepolizumab (Anti-IL-5)

Mepolizumab is a humanized monoclonal antibody against IL-5 (key cytokine for eosinophil differentiation and survival)
MIRRA Trial (Phase III RCT): Mepolizumab vs. placebo as add-on therapy in relapsing/refractory EGPA
- 28% vs 3% had ≥24 weeks of accrued remission (P<0.001)
- Higher percentage in remission at weeks 36 and 48 (32% vs 3%; P<0.001)
Best suited for: EGPA not controlled with glucocorticoids alone, low FFS, ANCA-negative EGPA patients
Note: mepolizumab alone or with <5 mg/day prednisolone does not maintain remission in the majority
Reslizumab (anti-IL-5) and benralizumab (anti-IL-5 receptor) are under investigation

E. Rituximab (Anti-CD20)

Used in: refractory EGPA or when cyclophosphamide is contraindicated
Retrospective data: improvement in 76.8% at 6 months, 82.8% at 12 months, 93.2% by 24 months
Relapses (particularly asthma and ENT) in 54% by 24 months
ANCA-positive subset: more sustained response
Active trials: REOVAS (vs. cyclophosphamide for induction) and MAINRITSEG (vs. azathioprine for maintenance)
Data remain insufficient to definitively recommend rituximab broadly for EGPA

F. Plasma Exchange (TPE)

Rarely used; theoretically useful in ANCA-positive EGPA patients with severe pulmonary-renal syndrome failing CS and cyclophosphamide

Fishman's Pulmonary Diseases and Disorders (blocks 13 and 15); Murray & Nadel's (Chs. 87 and 96)

13. Disease Severity Classification (Treatment Stratification)

Class	Features	Treatment
Non-organ-threatening	Rhinosinusitis, exanthem, pulmonary nodules without systemic organ involvement	Glucocorticoids ± MTX/AZA/MMF
Organ- or life-threatening	Rapidly progressive renal disease, pulmonary hemorrhage, motor neuropathy, cardiac involvement, GI bleeding	Cyclophosphamide + glucocorticoids OR Rituximab + glucocorticoids
Refractory	Disease flares during steroid taper or requires ≥7.5 mg prednisone to control	Escalate to cyclophosphamide or biologics (mepolizumab)

Murray & Nadel's (Ch. 87, Table 87.4)

14. Monitoring

Birmingham Vasculitis Activity Score (BVAS v3.0): Quantifies disease activity
Vasculitis Damage Index (VDI): Tracks cumulative organ damage
Routine cardiac surveillance for all EGPA patients (ECG, echo, troponin, NT-proBNP)
Cardiac MRI for suspected myocardial involvement

15. Summary of Key Distinguishing Features of EGPA vs. GPA/MPA

Feature	EGPA	GPA	MPA
Asthma	Always present	Absent	Absent
Eosinophilia	Universal	Absent	Absent
ANCA	30-70% (p-ANCA/MPO)	70-90% (c-ANCA/PR3)	50-80% (p-ANCA)
Upper airway destruction	Rare	Common (saddle nose, septal perforation)	Rare
DAH	Rare	Common	Common
Renal failure	Less common	Common	Common
Mononeuritis multiplex	Very common (63-93%)	Less common	Less common
Cardiac involvement	Common (16-56%)	Rare	Rare
Granulomas	Yes (eosinophilic, extravascular)	Yes (necrotizing)	No

Sources:

Fishman's Pulmonary Diseases and Disorders, 2-Volume Set - Chapters on DAH/Vasculitis and EGPA Clinical Presentation/Treatment
Murray & Nadel's Textbook of Respiratory Medicine, 2-Volume Set - Chapters 87 (Pulmonary Vasculitis) and 96 (Eosinophilic Lung Diseases)

This is a shared conversation. Sign in to Orris to start your own chat.