Abstract Introduction Pulmonary alveolar microlithiasis is a rare disorder characterized by the deposition of microliths within the lung alveoli. It has a reported incidence of less than 1 per million. Case Description Patient is a 63 year-old male of Italian descent with past medical history of hypertension, gout, and hyperlipidemia who is presenting with complaints of dyspnea on exertion and cough. The symptoms have been present for many months. The cough is described as dry, occurs more frequently in the morning. Dyspnea on exertion occurs with minimal activity such as climbing stairs. Chest x-ray revealed interstitial markings bilaterally with possible miliary pattern. CT chest revealed miliary nodular pattern throughout both lung bases. Pulmonary function test revealed FEV1 95%, FVC 87%, FEV1/FVC 88%, TLC 72%, DLCO 90%. He underwent bronchoscopy with transbronchial lung biopsies which revealed bronchial wall tissue and alveolar parenchyma with calcifications and focal ossification, negative for granuloma or malignancy. Extensive infectious workup was negative. The diagnosis of pulmonary alveolar microlithiasis was made. He was followed for 5 years without drastic change in his lung CT scans. Discussion Pulmonary alveolar microlithiasis is a rare disorder characterized by the presence of microliths within the alveolar spaces. It can be sporadic or familial, caused by mutations in the gene SCL34A2 which encodes a sodium phosphate co transporter. This leads to accumulation of calcium phosphate microliths. As of 2020, there were only 1100 cases reported. Turkey, China, Italy, and the United States have the highest number of reported cases. Clinically, there is often dissociation between the clinical picture and the radiographic appearance. When symptomatic, patients most commonly experience dry cough and dyspnea on exertion. PFTs may be normal initially, however subsequently demonstrate restrictive pattern with reduction in DLCO. Computed tomography imaging of the lung usually reveals diffuse micronodular calcified infiltrations bilaterally. Radiographic involvement has been divided into stages, ranging from from precalcific phase, to sand storm appearance, and eventually white lungs. The diagnosis can be made based on genetic testing and radiographic appearance, however BAL and transbronchial biopsy can be useful when the diagnosis remains uncertain. Lung transplant remains as the only definitive treatment. Etidronate has been used, but not routinely recommended. Counseling against smoking is important as it can cause accelerated disease progression. Conclusion Pulmonary alveolar microlithiasis is a very rare disease that can have striking radiographic presentation. We are hereby presenting a case highlighting important aspects of this disease’s presentation. This abstract is funded by: None
Al-Bayati et al. (Fri,) studied this question.