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The Clinical Course of Progressive Pulmonary Alveolar Microlithiasis FREE TO VIEW

Ahlam Al Awadi, MD; Wagih Djazmati, MD; Yaser Abu El-Sameed, MBBS
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Sheikh Khalifa Medical City, Medicine Institute, Abu Dhabi, United Arab Emirates

Chest. 2013;144(4_MeetingAbstracts):940A. doi:10.1378/chest.1701171
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SESSION TITLE: Miscellaneous Global Case Reports

SESSION TYPE: Global Case Report

PRESENTED ON: Tuesday, October 29, 2013 at 01:30 PM - 02:30 PM

INTRODUCTION: Pulmonary alveolar microlithiasis (PAM) is a rare lung disease characterized by calcium deposition in the alveolar spaces. We present a case of progressive PAM associated with severe pulmonary hypertension (PH). Our case outlines the course of a PAM patient who was not a candidate for lung transplant.

CASE PRESENTATION: A 48-year old morbidly obese male presented in 2004 with worsening shortness of breath (SOB) over few years. The SOB was associated with occasional cough and sputum production. He denied chest pain, hemoptysis and wheezing. He had a 40 pack-year smoking history. His past medical history was significant for psoriasis. He was married with five children and worked as a musician. None of his family members had a similar illness. On physical exam, his oxygen saturation was 90% on ambient air. He had clubbing but no cyanosis. His cardiac exam was normal. Chest exam showed few crackles bilaterally. No edema was noted. Chest x-ray (CXR) showed diffuse micronodular opacities. His pulmonary function testing (PFT) showed moderate restriction with Total Lung Capacity of 58% predicted. DLCO was not available. Arterial blood gas (ABG) showed pH of 7.41, pCO2 of 40.4 mmHg, PaO2 of 50.2 mmHg. Electrocardiography showed sinus rhythm with evidence of right axis deviation. His echocardiogram was normal. A High Resolution Computed Tomography (HRCT) of the chest showed extensive nodular calcific densities in both lungs. There was thickening and calcification of the interlobular and intralobular septa. Patchy areas of ground glass haziness were present. The subpleural interstitium had evidence of calcification. Bronchoscopy and transbronchial biopsy showed the lung parenchyma with multiple spaces filled by lamellar calcifications. Given the above, the patient was diagnosed with PAM. He was given home oxygen, counseling on smoking cessation, and enrolled in a dietary program to lose weight. The patient was able to quit smoking; however, he failed to reduce his weight. Therefore, he was declined lung transplantation. His SOB continued to progress and later developed worsening lower extremity edema. Follow up PFT in 2009 showed a TLC of 46% predicted and of DLCO 34% predicted. His echocardiography then showed evidence of PH with pulmonary artery systolic pressure of 60 mmHg and moderate right ventricular dysfunction. He was started on alendronate without improvement. He was tried on different pulmonary arterial vasodilators, of which, he was able to tolerate Sildenafil. He continued to suffer from severe cardiopulmonary limitations, on the above symptomatic therapies.

DISCUSSION: Pulmonary alveolar microlithiasis (PAM) is a rare lung disorder with autosomal recessive inheritance. A mutation in SLC34A2 gene causes a defect in the sodium-phosphate co-transporter type IIb which is responsible for phosphate homeostasis. This results in phosphate accumulation in the tissues and subsequently microlith formation. Diagnosis is usually done incidentally by the typical sandstorm appearance on the CXR. Symptoms range between SOB, dry cough, chest pain, hemoptysis and asthenia. PFT and ABG show restrictive pattern and hypoxemia, respectively. Ground glass opacities and subpleural linear calcifications are the most common findings on HRCT. These opacities typically involve the lower lobes and progress gradually to spread throughout the lung fields. No effective therapy is currently available to stop the progression of PAM. The main treatment for these patients is lung transplantation. The course of PAM is progressive, usually over 10 to 20 years. It results in an advanced pulmonary fibrosis, respiratory failure, and death.

CONCLUSIONS: PAM is a rare autosomal recessive lung disease characterized by widespread intra-alveolar calcification. Without lung transplant, it leads to severe respiratory impairment and eventually death.

Reference #1: Ferreira Francisco FA et al. Pulmonary alveolar microlithiasis. State-of-the-art review. Respir Med 2013;107(1):1-9.

DISCLOSURE: The following authors have nothing to disclose: Ahlam Al Awadi, Wagih Djazmati, Yaser Abu El-Sameed

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