Case reportLung cancer may develop subsequently or coincidently with pulmonary alveolar proteinosis
Introduction
Pulmonary alveolar proteinosis (PAP) is a rare diffuse lung disease characterized by the accumulation of amorphous, periodic acid–Schiff (PAS)-positive lipoproteinaceous material in the alveolar spaces. These lipoproteinaceous materials are composed principally of the phospholipid surfactant and surfactant apoproteins. PAP are usually categorized in three clinically diverse forms: congenital, secondary, and idiopathic PAP [1], [2]. The congenital PAP involves a heterogeneous group of disorders, which are characterized mainly with gene mutations in encoding surfactant protein B or C or the βC chain of the receptor for granulocyte–macrophage colony-stimulating factor (GM-CSF). Secondary PAP occurs with respect to other underlying causes. Currently, recognized conditions include hematologic malignancies, immunodeficiency disorders, inhalation of inorganic dust (e.g., silica), and certain infections [2]. Idiopathic PAP, the most common form, develops in adults, usually as an isolated idiopathic lung disease without a definite aetiology. The majority of idiopathic PAP patients had elevated serum levels of neutralizing anti-GM-CSF antibodies, which were not seen in patients with congenital and secondary PAP. In a review of the literature, only five case reports of PAP associated with solid organ cancers were found [3], [4], [5], [6], [7]. We herein report two cases of PAP associated with lung cancer.
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Case 1
A 54-year-old female, non-smoker, was diagnosed with idiopathic PAP with the initial presentation of insidious dyspnea on exercise for 1 year. The initial chest radiography (CXR) in November 2000 disclosed bilateral symmetrical ground glass opacity in the lower lung field. Chest tomography (CT) revealed a bilateral symmetrical, crazy-paving appearance with geographic distribution, mainly in the lower lung field. The patient then underwent diagnostic bronchoalveolar lavage (BAL), and the
Discussion
PAP is rare, with fewer than 500 reported cases since it was first described in 1958. Seymour reported the patients were diagnosed at the median age of 39 years, the median duration of symptoms prior to diagnosis was 7 months, the male-to-female ratio was 2.65:1, and 72% were smokers [1]. The CXR presents typically bilateral, symmetrical alveolar, interstitial and mixed infiltrates, distributed in the lower more than the upper lung fields, with sparing of costophrenic angles. Chest CT reveals a
Conclusion
PAP can occur prior to or coincidently with lung cancer. A regular chest CT follow-up is a better choice than CXR. Further aggressive investigation is needed when a pulmonary nodule is found in PAP patients.
Conflict of interest
None declared.
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These authors contributed equally to this work.