A case of Pulmonary alveolar microlithiasis mimic TB

Introduction : Pulmonary alveolar microlithiasis (PAM) is a rare pulmonary disease in which there is deposition of calcium phosphate microliths within the alveoli (1). The etiology of PAM is unclear; however, one of the probable causes may be isolated inborn errors of calcium metabolism and it could be regarded as hereditary autosomal recessive lung disease (2).The disease is usually discovered from birth up to 40 years of age, and is mostly diagnosed incidentally during pulmonary radiography of the chest for other reasons (3-6).Case report : A 20-year-old woman presented with chronic cough. Two years ago with diagnosis of miliary TB Pharmacologic therapy for 9 months, without any improvement. She reported dry cough but denied fevers, night sweats and weight loss. Chest -X ray shows multiple small calcified densities in both lungs with lower and middle zone dominantly. A cavity was seen in middle zone of right lung. In HRCT innumerable small calcified densities in both lungs. Patient was undergone trans bronchial lung biopsy. Histology shows concentric laminated microliths and calcospherites in the alveoli along with thickened interstitial septa, confirming the diagnosis of PAM. Discussion : PAM is an autosomal recessive disease that seen in both male and female (8) predominates in a few countries, particularly Turkey, Italy and the USA. The etiology of disease is mutations of the SLC34A2 gene, which encodes a type IIb sodium-dependent phosphate co-transporter (NaPi-IIb) (11) Clinical features are non-productive cough and dyspnea and chest pain (12). Trans bronchial lung biopsy reveals several alveoli are lined by pneumocytes with slightly inflammatory mononuclear cell infiltration in alveolar interstitium. Alveolar space filling with calcospherites Extra pulmonary manifestations that reported includes medullary nephrocalcinosis and/or nephrolithiasis , calcification of the lumbar sympathetic chain and possible testicular involvement ,calcifications in the seminal vesicles , and epididymal and periurethral calcifications that lead to obstructive azospermia (18-23).other co morbidities include mitral and aortic valve calcification and stenosis ,hypertrophic pulmonary osteoarthropathy,pectus excavatum, milk-alkali syndrome, lymphocytic interstitial pneumonitis and diaphyseal aclasia (24-27). As regards other diseases like sarcoidosis and TB to be considered as differential diagnosis with PAM, in patient like this case that not respond to standard treatment should be revaluated for other diagnosis.

کلیدواژه ها:

lung ، microlithiasis ، TB