View Abstract

A1563 - Pulmonary Alveolar Microlithiasis with Satisfactory Diagnosis by Bone Scintigraphy of the Lung
Author Block: F. Alkhankan1, E. Alkhankan2, H. S. Bukamur2, H. Alkhankan3, A. Amro2, I. Shahoub2, Y. R. Shweihat4, F. M. Zeid2; 1Pulmonary / Critical Care Medicine, McLaren Oakland, Pontiac, MI, United States, 2Pulmonary Medicine, Marshall University, Huntington, WV, United States, 3Pulmonary Critical Care medicine, Mercy hospital/ Saint Louis University, Saint Louis, MO, United States, 4Interventional Pulmonary, Marshall University, Huntington, WV, United States.
Introduction
Pulmonary alveolar microlithiasis (PAM) is a unique condition caused by intra-alveolar deposition of spherical calcium phosphate microlith due to a mutation of sodium-phosphate co-transporter. We present a case of an atypical age of the disease in a female with complaints of progressive shortness of breath on exertion. Diagnosis was supported by a limited bone scintigraphy scan of the lung.
Case Presentation
A 67-year-old female presented with slowly progressive shortness of breath on exertion for five years. She was a non-smoking teacher by profession with no previously known pulmonary disease until 2012 when she had incidental bilateral infiltrates on X-ray scans. She was then thought to have suspected interstitial lung disease; however, no further workup was done at that time. She was treated with steroids with no improvement. She was asymptomatic for years until her shortness of breath started to become more prominent with light activity. Bilateral fine crackles were noted on auscultation with finger clubbing. A chest radiograph showed bilateral diffuse opacities with sand-like appearance. A chest CT showed PAM characteristic intra-alveolar microliths, calcified interlobular septa, and diffuse ground-glass attenuation with septal thickening. Limited bone scans of the lung with technetium-99 labeled showed diffuse bilateral pulmonary uptake compatible with alveolar microlithiasis.
Discussion
PAM is an intra-alveolar accumulation of microliths due mutation of the SLC34A2 gene causing deactivating in the sodium-dependent phosphate co-transporter located in type II cells, leading to accumulation of phosphate in the alveolus, and calcium phosphate microliths. This disease is typically diagnosed accidently between 30 and 50 years of age with no significant gender differences. Chest radiographic findings shows diffuse, sand-like infiltration, particularly in lower bases and may include black pleura sign. CT scan of the chest shows numerous sand-like calcifications throughout the lungs with subpleural and peribronchial distribution. Bone scintigraphy of the lung using technetium-99 labeled diphosphonate compounds have affinity for calcification foci at soft tissue and can detect early pulmonary calcification. There is no treatment available for this disease. Our patient presented with atypical age and lung biopsy was not performed as she had supportive imaging of bone scintography of the lung favoring her diagnosis.
Conclusion
PAM is rare and should be considered for any age of patient with diffuse parenchymal disease revealed on a chest CT. Bone scintigraphy of the lung is a useful way to support the diagnosis