A 63 year old man working as a salesman was referred to the respiratory team for clinical management of his progressive shortness of breath and deteriorating exercise tolerance that significantly worsened over the last 12 months. In terms of medical history, he mentioned an occasional left-sided pleuritic chest pain with no other exercise related pain, no peripheral swelling, no weight loss and no night sweats. He suffered for one episode of spontaneous pneumothorax on each side during the last year which was treated conservatively. He also mentioned diet controlled diabetes and hypercholesterolemia managed with Simvastatin. He is a non-smoker, he denied exposure to birds or pets, he does not have any allergies and he has no history of tuberculosis. With reference to the family history, his sister passed away from pulmonary alveolar microlithiasis at the age of 54. His 37 year old daughter is treated for hypertension and hypercholesterolemia with no evidence of lung disease. No information was available in regards of his parents. On physical examination, there were marked discrete inspiratory crackles, cyanosis and digital clubbing, while all laboratory investigations were within normal limits. His chest X-ray (Fig. 1) was suggestive of extensive interstitial bilateral lung disease and the differential diagnosis was suggested to be either a microlithiasis or an atypical infection. A high resolution computed tomography (HRCT) (Fig. 2) of the chest was performed and revealed several calcifications throughout the parenchyma, ground-glass opacities, sub-pleural cystic changes and calcified interlobular septa. Considering the findings on the CT scan, his case was discussed in our multidisciplinary meeting and patient was referred to our Department for surgical lung biopsy. After written consent was obtained from the patient, a right uniportal VATS biopsy of the lung was performed. The right lung was diffusely involved and the parenchyma was thickened with occasional superficial bulla. The postoperative course was unremarkable and the patient was discharged in stable condition on the 2nd postoperative day.
Subsequent histological examination of the specimens was performed. Section showed lung parenchyma with marked sub-pleural and interstitial fibrosis and patchy chronic inflammation. The alveolar spaces were filled with numerous calcified bodies which showed concentric lamination and radial striations (Fig. 3, Fig. 4). Microliths were also present within the areas of fibrosis (Fig. 5, Fig. 6). There was no evidence of atypia or malignancy. The diagnosis of pulmonary alveolar microlithiasis was made considering the histological features and the radiological image. Regarding the treatment plan, during a multidisciplinary meeting the conservative approach was decided with a re-evaluation period of 6 months. The option of lung transplantation was rejected due to patients' age.