What is allergic granulomatosis?
Allergic granulomatosis, also called Churg-Strauss syndrome (CSS), is a disorder than affects many body systems and is characterized by the prominence of allergic features, specifically:
CSS can affect any organ system but primarily targets the lungs and skin. It is characterized as a one the “vasculitides” meaning it is a subtype of a group of diseases that are characterized by inflammation of the blood vessels (vasculitis). There are 3 different phases of CSS, an individual may have one or all of these phases occurring at once:
In severe cases CSS can affect other organs such as the heart, kidneys, muscles and digestive system.
What causes allergic granulomatosis?
The cause of CSS remains unclear. The disease is most likely an autoimmune process in which the body over-produces antibodies. In CSS these are called IgE antibodies and they are produced by eosinophils. Having a high amount of these IgE antibodies in your body causes allergic features of the disease to develop. In addition, these circulating antibodies clump together and form a complex of immune cells that deposit in the lungs, skin and blood vessels causing granulomas to form. A granuloma is a cluster of cells and debris, if located just under the skin they look like papules and nodules. Why a certain individual develops this disease is unknown, genetic factors are thought to play a role and some medications have been associated with development of CSS. Medications that alter the body’s allergy-inducing proteins (leukotrienes) may help unmask the disease.
How is allergic granulomatosis diagnosed?
Diagnosis of allergic granulomatosis requires clinical findings and symptoms (asthma, rhinitis, skin rash) and lab tests. There are no lab tests that are specific for CSS, but when combined with clinical symptoms they can be helpful. Imaging studies such as chest x-rays can be helpful in visualizing lung granulomas and lung biopsy is considered the gold standard for the diagnosis of CSS. When looked at under the microscope a lung biopsy reveals patterns and features that are unique to CSS.
How is allergic granulomatosis treated?
The primary therapy for CSS is systemic glucocorticoids (steroids). Asthma is locally treated with inhaled glucocorticoids as well. Glucocorticoids work by suppressing the body’s immune response and are taken for 6 to 12 weeks or until disease symptoms have resolved. After an initial course of steroid therapy the patient may discontinue use and late relapses are uncommon. Some patients may need to take long-term steroid therapy.