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Diagnosis of CSS

Churg Strauss Syndrome

WHAT IS CSS?
Churg-Strauss syndrome (CSS) is a difficult to treat syndrome manifested by not just asthma, but also, eosinophilic vasculitis, an inflammation of the blood vessels characterized by high levels of blood eosinophils. CSS is characterized by involvement of many different organ systems, particularly the sinuses, the lungs, and the nerves. However, it can also directly affect the heart, the gastrointestinal tract, the genitourinary system, and the skin.

First described by pathologists Churg and Strauss in the 1950’s as “allergic granulmomatosis and angiitis”(1), there is evidence that this entity long predated the description of these two pathologists. Indeed, it appears that this syndrome even existed at the turn of the century and that the great physician Osler may have been one of the first to describe such a case(2).

This syndrome has evolved significantly since Churg and Strauss described this constellation of pathologic findings and several criteria have been used to define this condition. In 1984, Lanham et al. noted that not all cases have the extravascular granulomas, necrotizing vasculitis, nor eosinophilic tissue infiltration that characterized the original cohort of patients and they emphasized a more clinical approach to this disease (3). According to the Lanham criteria, CSS is defined by asthma, peripheral eosinophilia, and systemic vasculitis involving 2 or more organ systems. Today, however, the most commonly used criteria to describe CSS are those adopted by the American College of Rheumatology in 1990(4). The ACR criteria include both clinical and pathologic features and define CSS as presence of 4 of the following 6 features: asthma, eosinophilia, neuropathy, pulmonary infiltrates, paranasal sinus abnormality, and presence of eosinophilic vasculitis (Table 1).

ETIOLOGY OF CSS
Pathologically, CSS is characterized by tissue infiltration by eosinophils, extravascular granulomas and necrotizing vasculitis. However, the cause of CSS remains unknown Because of the prominence of many allergic features, CSS is thought to result from an interaction of genetics and the environment, complicated by an immune system gone out of whack. Because all patients with CSS have high levels of eosinophils at some point during their disease, it is thought that there may be some dysregulation of eosinophil production, maturation, or development. Anti- neutrophil cytoplasmic antibodies (ANCA) are also present in many patients with CSS and may also play a role in CSS pathogenesis. While the exact role of ANCA in CSS and other vasculitides remains unclear, it is felt that the binding of ANCA to vascular walls contributes to vascular inflammation and injury as well as chemotaxis of inflammatory cells. While CSS has been associated with various asthma therapies, including leukotriene modifiers(5;6) and inhaled corticosteroids(7), no causal link has been established. It appears that the syndrome either occurs coincidental to these medications or that these medications facilitate systemic steroid withdrawal that unmasks the syndrome.

CSS EPIDEMIOLOGY AND CLINICAL FEATURES
It has been estimated that CSS occurs in about 5 cases per million people per year, with a rate in asthmatics of as high as 80 cases per million per year(8). However, it is probable that CSS occurs with greater frequency and is underreported due to underdiagnosis of this poorly understood syndrome or due to masking of findings by treatment with corticosteroids of what is perceived to be just severe asthma.
Both men and women are affected by CSS. While it is generally diagnosed in adulthood, it has also rarely been described in children. Usually, individuals have asthma and allergic rhinitis that persists for years. It often arises later in life and occurs in individuals with no family history of asthma or allergies. Eventually, a second phase with eosinophilia ensues, followed by a vasculitic phase characterized by involvement of multiple organ systems. Fever, weight loss, fatigue and malaise often accompany the syndrome and are frequently debilitating.
The lungs are the most frequently involved organ system involved by CSS. In addition to asthma, most patients develop pneumonia and have symptoms of shortness of breath and cough. Neurologic symptoms occur in three quarters of patients, with mononeuritis multiplex being the most frequent manifestation. Weakness and paresthesias can be disabling and often fail to respond to treatment. Half of patients present with rashes of all types that are often biopsied to help establish a diagnosis. Involvement of the heart, usually with cardiomyopathy or myocarditis, often portends a worse prognosis. Gastrointestinal symptoms can occur and usually include abdominal pain and diarrhea; ischemic bowel disease and inflammation of the pancreas or gallbladder are often the culprits.
While high levels of blood eosinophils in the presence of asthma and pneumonia are the tip-off for diagnosis, elevated sedimentation rates (ESR) or C-reactive protein, and the presence of anti-neutrophil cytoplasmic antibodies are supportive evidence. A biopsy of an affected organ is not required to establish the diagnosis of CSS, however it is often done to distinguish CSS from Wegener’s Granulomatosis, eosinophilic pneumonia, fungal and parasitic infections and malignancy.

American College of Rheumatology 1990 Classification criteria for Churg-Strauss syndrome (4)
1. Asthma
2. Eosinophilia> 10% in peripheral blood
3. Paranasal sinus abnormality
4. Pulmonary infiltrates
5. Mononeuropathy or polyneuropathy
6. Extravascular eosinophils on biopsy.
A patient is said to have CSS if at least 4 of these 6 criteria are met. If 4 of 6 criteria are met, the sensitivity is 85% and the specificity is 99.7%

Reference List

(1) Churg J, Strauss L. Allergic granulomatosis, allergic angiitis and periarteritis nodosa. Am J Pathol 1951; 27:277-301.
(2) Warren P. Osler's unusual case — Was it Churg­Strauss syndrome? Can Med Assn J 1999; 161(7):846-847.
(3) Lanham JG, Elkon KB, Pusey CD, et al. Systemic vasculitis with asthma and eosinophilia: a clinical approach to the Churg-Strauss syndrome. Medicine 1983; 63:65-81.
(4) Masi AT, Hunder GG, Lie JT, Michel BA, Bloch DA, Arend WP et al. The American College of Rheumatology 1990 criteria for the classification of Churg-Strauss syndrome (allergic granulomatosis and angiitis. Arthritis Rheum 1990; 33(8):1094-1100.
(5) Wechsler ME, Garpestad E, Flier SR, Kocher O, Weiland D.A., Polito AJ et al. Pulmonary infiltrates, eosinophilia, and cardiomyopathy following corticosteroid withdrawal in patients with asthma receiving zafirlukast. JAMA 1998; 279:455-457.
(6) Wechsler ME, Finn D, Gunawardena D, Westlake R, Barker A, Haranath SP et al. Churg-strauss syndrome in patients receiving montelukast as treatment for asthma. Chest 2000; 117:708-713.
(7) Le Gall C, Pham S, Vignes S, Garcia G, Nunes H, Fichet D et al. Inhaled corticosteroids and Churg-Strauss syndrome: a report of five cases. Eur Resp J 2000; 15(5):978-981.
(8) Wechsler ME, Pauwels R, Drazen JD. Leukotriene modifiers and Churg-Strauss Syndrome: Adverse effect or response to corticosteroid withdrawal? Drug Safety 1999; 21:241-251.

BIOGRAPHY OF AUTHOR
Dr. Michael Wechsler is a specialist in Pulmonary and Critical Care at Brigham and Women’s Hospital in Boston, MA and is on the faculty of Harvard Medical School. He is on the Steering Committee of the NIH’s Asthma Clinical Research Network and is active in clinical research involving both asthma and Churg-Strauss syndrome.

© American Partnership for Eosinophilic Disorders (APFED) 2008, 2009, 2010, 2011. All rights reserved.
Updated 3-11-2011
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