Pulmonary alveolar microlithiasis: A report of two unique cases

Abstract

Pulmonary alveolar microlithiasis (PAM) is an inherited autosomal recessive disease. PAM is classically characterized by calcium phosphate deposition within alveolar airspaces due to SLC34A2 (solute carrier family 34 member 2) gene mutation located on chromosome 4p15.2. Such cellular genetic mutation would lead to a defect in the sodium-phosphate transporter channel located in alveolar epithelial cells type-II. Ultimately, it would result in a malfunction of alveolar epithelial cells and the failure of these cells to clear-up the released phosphorous particles in the cellular surfactant recycling. PAM is usually diagnosed in adulthood, frequently notable in the third and fourth decades of life, occasionally can be associated with more severe clinical presentation and radiological findings. Nevertheless, the disease could manifest itself in the pediatric age group, which either shows non-specific signs and symptoms or be exclusively asymptomatic. Histopathological examination is the gold standard for the PAM diagnosis. Genetic counseling and testing might benefit the patient's family members. Herein, we present 2 cases of PAM in the pediatric age group, along with their clinical history, presentation, radiological studies, and histopathology findings, as well as a brief literature review.

Keywords: Lung; Pediatric; Pulmonary alveolar microlithiasis; SLC34A2; Solute carrier family 34 members 2.

Fig. 1

Radiologic photo and Histopathologic hematoxylin and eosin-stained (H&E) sections. (A): Lung window; and (B): Soft tissue window CT scan shows diffusely scattered parenchymal micronodules and calcifications with exaggerated distribution along the major fissures (red arrow), not continuous with pulmonary air spaces. (C): (H & E; 4x) and (D): (H & E; 10x) numerous lamellated calcified structures within alveolar spaces consistent with pulmonary microlithiasis. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 2

(A): CT scan without contrast shows diffuse ground-glass opacification primarily involving the upper lobes (bilateral) and right middle lobe with an associated interlobular septal thickening. (B): Soft tissue window of lung-CT scan reveals suspicious white opacity located at the middle lobe of the right lung, not continuous with the air spaces branches (yellow arrow). (C): (H & E; 4x) and (D): (H & E; 10x) numerous lamellated calcified structures within alveolar spaces consistent with pulmonary microlithiasis.