A 62-year old female with history of severe persistent asthma on chronic steroid and montelukast, allergic rhinitis, and peripheral neuropathy who presented with a two- month history of worsening left foot weakness. On examination, vital signs were normal, musculoskeletal exam was significant for intact strength in the upper extremities bilaterally. Right lower extremity strength was normal. Left lower extremity was noted to have 0-1 out of 5 strength on dorsiflexion, eversion and inversion. Left hip flexion was weak 3-4 out of 5. A decrease in sensation was noted over the dorsal aspect of the feet bilaterally. Patellar and Achilles reflexes were absent bilaterally. Laboratory studies showed WBC of 16.6 h/mm³ with 60% eosinophilia, elevated erythrocytes sedimentation rate (ESR) and C-Reactive protein (CRP), and positive Anti- neutrophil cytoplasmic antibodies (C-ANCA). B12 and folate levels were normal. Rapid plasma reagin (RPR) was negative. CT scan of the chest showed a new 3-4 mm lingular pulmonary nodule along with a left sided pleural effusion. EMG study showed electrophysiologic evidence of sensorimotor peripheral polyneuropathy likely representing mononeuritis multiplex. A left sural nerve biopsy showed evidence of necrotizing arteritis associated with giant cell/eosinophilic inflammation, and axonal degeneration. The patient met 4/6 of the American College of Rheumatology (ACR) criteria for EGPA. Montelukast was discontinued in our patient and she was discharged on a prednisone taper.
Discussion:
Eosinophilic granulomatosis with polyangitis (EGPA) or formerly known as Churg Strauss is a rare form of eosinophilic necrotizing vaculitis mainly involving small to medium sized blood vessels. To make a diagnosis of EGPA, 4 out of 6 criteria set by the ACR must be met: history of asthma,>10% eosinophilia, mono- or poly-neuropathy, non- fixed pulmonary nodules, para-nasal sinus abnormalities, and biopsy proven extra-vascular eosinophilia. Multiple case reports have proposed a link between EGPA and anti-leukotriene receptor antagonists (ALRA) such as montelukast. The role of ALRA in the development of EGPA is still unclear, however; one of the proposed theories suggests that ALRA cause an imbalance in leukotriene receptors stimulation by antagonizing the synthesis of some leukotrienes such as LTC4, LTD4, LTE4, but not LTB4. Studies have shown that LTB4 plays a role in the stimulation of eosinophilia and possibly could contribute to EGPA.
Conclusions:
We presented an asthmatic patient with a new diagnosis of Eosinophilic granulomatosis with polyangitis (EGPA). We explored the potential association between EGPA and anti-leukotriene receptor antagonists (ALRA). Although ALRA is an effective class of medications in asthmatics, providers should be vigilant of the potential increased risk of EGPA.