SESSION TYPE: Cancer Cases II
PRESENTED ON: Tuesday, October 23, 2012 at 11:15 AM - 12:30 PM
INTRODUCTION: “Crazy paving” on computed tomography (CT) coupled with periodic acid Schiff (PAS) staining suggests a diagnosis of pulmonary alveolar proteinosis (PAP) in the appropriate clinical context. However, neither test is specific. Advances in serologic testing for PAP and genetic testing obtained by bronchoscopic samples for lung cancer have altered diagnostic algorithms for both diseases. We present a unique case of diffuse lung adenocarcinoma initially masquerading as PAP.
CASE PRESENTATION: A 54 year-old former smoker presented with progressive dyspnea and bronchorrhea. Her medical history included venous thromboembolism and social history included welding industrial copper wires. Chest x-ray revealed bilateral pulmonary infiltrates, and hypoxemia progressed despite two courses of antibiotics. After requiring intubation, CT showed diffuse ground glass opacities with smooth inter-/intra-lobular septal thickening and multiple areas of consolidation (Fig. 1). Bronchoalveolar lavage fluid (BALF) revealed copious PAS-positive granular material. After transfer to our institution for progressive respiratory failure, urgent left-sided segmental whole lung lavage (WLL) was performed, and anti-GM-CSF antibody testing was requested. BALF had less sediment than expected for classic PAP. Repeat WLL was performed with unilateral lung ventilation followed by transbronchial biopsies (TBBx). Anti-GM-CSF antibody testing was negative, and TBBx revealed non-mucinous invasive adenocarcinoma with micropapillary and lepidic growth pattern (Fig. 2) with positive KRAS mutation. The patient was started on carboplatin and pemetrexed chemotherapy while on mechanical ventilation and was ultimately extubated, able to leave the hospital for ongoing care.
DISCUSSION: “Crazy paving” is classically found in PAP. The differential also includes malignancy, Pneumocystis carinii pneumonia, sarcoidosis, adult respiratory distress syndrome, and others. Though positive PAS staining of BALF material suggests PAP, it too is non-specific. As it stains for glycoproteins, it can be positive in lung cancer, sarcoidosis, IPF, and others. Anti-GM-CSF antibody testing is sensitive and specific for PAP, whereas transbronchial biopsies may distinguish this from other conditions causing radiographic and cytologic similarities. Specifically, TBBx can be performed in critically ill, ventilator-dependent patients and obtain sufficient tissue to diagnose diffuse lung cancer, perform mutational analysis, and exclude other etiologies.
CONCLUSIONS: Whereas “crazy paving” and PAS staining suggest PAP, other disorders may manifest with both. Anti-GM-CSF antibody titers coupled with small volume TBBx can refine diagnostic dilemmas such as this, while providing necessary tissue for guiding therapy.
1) Rossi SE, et al. “Crazy-paving” pattern at thin-section CT of the lungs: Radiologic-pathologic overview. RadioGraphics 2003;23:1509-19
2) Trapnell BC, et al. Pulmonary alveolar proteinosis. NEJM 2003;349:2527-39
DISCLOSURE: The following authors have nothing to disclose: Kusum Mathews, O'Neil Green, Aditi Mathur, Jonathan Puchalski, Shyoko Honiden
No Product/Research Disclosure InformationYale School of Medicine, New Haven, CT