Mucoid impaction: a localized form of allergic bronchopulmonary aspergillosis.

Mucoid impaction is defined as the obstruction of proximal bronchi by mucous plugs and exudates. There are striking similarities between patients with mucoid impaction and those with allergic bronchopulmonary aspergillosis (ABPA), often referred to as "mucoid microimpaction." We evaluated three patients with mucoid impaction for diagnostic criteria of ABPA and human leukocyte antigen type. We found that certain human leukocyte antigen types were common among mucoid impaction patients and those with ABPA. It is possible that patients with mucoid impaction could represent a localized form of ABPA.