|Year : 2020 | Volume
| Issue : 2 | Page : 183-185
First report of pulmonary alveolar microlithiasis diagnosed by cryobiopsy
Manoj Kumar Goel, Ajay Kumar, Gargi Maitra
Department of Pulmonology, Critical Care and Sleep Medicine, Fortis Memorial Research Institute, Gurugram, Haryana, India
|Date of Submission||11-Oct-2019|
|Date of Acceptance||26-Nov-2019|
|Date of Web Publication||27-Feb-2020|
Manoj Kumar Goel
Department of Pulmonology, Critical Care and Sleep Medicine, Fortis Memorial Research Institute, Gurugram, Haryana
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Goel MK, Kumar A, Maitra G. First report of pulmonary alveolar microlithiasis diagnosed by cryobiopsy. Lung India 2020;37:183-5
Pulmonary alveolar microlithiasis (PAM) is characterized by the widespread intra-alveolar accumulation of innumerable minute calculi called microliths. PAM is caused by inactivation of the gene SLC34A2, due to which the alveolar type II cells are unable to clean up the phosphorus ion from the alveolar space resulting in its accumulation forming microliths rich in calcium phosphate. Till date, more than 1000 cases have been reported worldwide and possibly 30 from India.,,, We describe herein a case in whom we performed cryobiopsy of the lung to confirm the diagnosis of PAM.
BK, a 24-year-old man, presented with the only complaint of progressive dyspnea on effort for 4 years. He was a smoker but denied any comorbid condition. He had exposure to the dusty environment being a soldier. His general and systemic physical examination was unremarkable. The routine blood investigations including serum calcium, phosphorus, and parathyroid hormone were within the normal range. The high-resolution computed tomography of the chest showed diffuse bilateral distribution of numerous calcific micronodules and circumferential pleural calcification appearing as a pencil-thin sharp dense white linear radiolucency all along the lung periphery [Figure 1]. Pulmonary function tests revealed postbronchodilator forced vital capacity (FVC) – 72%, forced expiratory volume-one second (FEV1) – 76%, FEV1/FVC – 90%, and the diffusion capacity – 65% of their respective predicted values. A video bronchoscopy was done, and transbronchial lung cryobiopsy (TBLC) was performed in the right middle and lower lobes to get 3 large specimens of lung tissue, largest measuring 7 mm in the maximum diameter. The histopathology examination confirmed the diagnosis of PAM in this case [Figure 2].
|Figure 1: High-resolution computed tomography chest (a) lung window showing numerous diffusely distributed sand-like calcific micronodules and bilateral interlobular septal thickening. (b) Mediastinal window showing bilateral circumferential pleural calcification|
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|Figure 2: Lung tissue specimens (a) obtained by transbronchial lung cryobiopsy and a specimen (b) measuring 7 mm in maximum diameter. H and E-stained section of lung biopsy (c) low power view (×40) showing numerous microliths within the alveolar spaces and (d) oil immersion (×1000) showing lamellar concretion|
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PAM is a rare lung disease which is a classic example of clinical and radiological dissociation. The diagnosis should be considered in an individual who has significant radiographic changes with no or very few symptoms and physical findings as was in this case who had only a mild restrictive dysfunction. This case presented with the typical radiological picture of PAM such as the sandstorm lung sign, circumferential pleural calcification, ground-glass opacities, and crazy paving pattern. The sandstorm lung sign is characterized by bilateral diffuse clearly outlined and bright calcific micronodules, distributed throughout the lungs, although with a greater concentration in the middle and inferior regions.
Chest radiograph and computed tomography scan remain the most important tool for the diagnosis of PAM. Although lung biopsy is the most definitive diagnostic procedure, it is not frequently performed. In a meta-analysis, Castellana et al. reported transbronchial biopsy (n = 175; 28.0%), open lung biopsy (n = 159; 25.4%), or autopsy (n = 20, 3.2%) in only limited number of cases of PAM. We report here the first case of PAM where diagnosis was confirmed by TBLC.
There is no effective medical treatment available for PAM. The use of disodium etidronate which reduces calcium phosphate precipitation remains controversial. Bilateral lung transplant in advanced cases is the only definitive treatment.
We have described here a case of PAM in whom the diagnosis was confirmed by TBLC which could be a safer and viable option to open lung biopsy in diffuse lung diseases.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]