Pulmonary Alveolar Microlithiasis
Description
● Introduction:
➣ Definition: PAM is an uncommon chronic lung disease that is typified by the alveoli's diffuse deposition of microliths, or calcium-phosphate concretions.
➣ Epidemiology:
• Usually manifests in adults between the ages of 20 and 40, but may go decades without showing any symptoms;
• has the biggest burden in Asia, with Turkey and Italy reporting the highest number of cases per population;
• has over 1,000 cases reported globally.
➣ Etiology:
• Autosomal recessive inheritance; mutations in the SLC34A2 gene, which codes for the sodium-dependent phosphate transporter type 2b (NaPi-IIb) in alveolar type II cells.
• Calcium-phosphate accumulation in alveoli due to impaired phosphate elimination.
● Discussion:
➣ Pathophysiology
• Chronic deposition results in alveolar fibrosis, restrictive lung disease, and progressive respiratory failure;
• SLC34A2 mutation results in impaired phosphate transport in alveolar type II cells, which leads to calcium-phosphate accumulation and microlith formation;
• Surfactant proteins (SP-A and SP-D) may function as biomarkers for disease activity, although this is not the case in this instance.
➣ Clinical Characteristics
• Frequently asymptomatic for many years.
•Restrictive lung disease develops over time; progressive dyspnoea with exercise is typical.
• Chronic phases of finger cramping may manifest.
•Cor pulmonale-related respiratory failure is the primary cause of mortality.
➣ Radiologic Evaluation
• Chest X-ray: Both sides have widespread micronodular calcifications (which give the appearance of a "sandstorm") that obliterate the edges of the heart and diaphragm, mainly in the middle and lower lung zones.
•HRCT: Features of pathognomonic Radiologically graded disease: Interlobular septal thickening and ground-glass opacities; Subpleural cysts dark pleural line;
• diffuse intra-alveolar calcifications Pre-calcific: lacks common characteristics. → Diffuse micronodular calcifications <1 mm during the snowstorm phase. The white lung phase is characterised by widespread calcifications, significant interstitial and pleural involvement, and interstitial thickening, which includes larger/more frequent nodules and obliteration of cardiac/diaphragmatic outlines.
● Research:
➣ Laboratory:
• Sputum HIV and AFB negative.
• The chemistry and blood counts were ordinary.
• Arterial blood gas: respiratory compensation along with metabolic alkalosis.
➣ Radiology:
• Chest X-ray: "black pleural line" (subpleural hyperlucency); bilateral, diffuse, high-density micronodules.
•HRCT: Subpleural cysts "black pleural line" sign; Ground-glass opacities and thickening of the septa; Large calcified micronodules along the interlobar septa and subpleural areas.
➣Bronchoscopy & Biopsy:
• Microliths are not present; bronchial tree patent.
• Inconclusive histology.
➣ Cardiac Findings:
• ECG: right atrioventricular enlargement and sinus rhythm.
• Echo: decreased LV contractility (EF 22%), mitral/tricuspid regurgitation, and dilatation of the ventricles.
• Due to clinical worsening, pulmonary function tests were not done.
● Case Summary:
➣ Patient: A 57-year-old male from Indonesia (Javanese).
➣ Background:
• Heavy smoker (40 pack-years); 12-year history of increasing dyspnoea during exercise.
• In 2018, pulmonary tuberculosis was treated.
➣ Physical examination:
• Occasional wheezing and coarse inspiratory crackles.
The "drumstick" fingers were clubbed.
• Cardiac examination: not noteworthy.
● Differential Diagnosis:
• Miliary tuberculosis (absence of calcification, dispersion at random, lymphadenopathy).
• Metastatic pulmonary calcification, which is linked to renal failure and hypercalcemia.
• Pneumoconiosis (perilymphatic distribution, upper-lobe predominance) and sarcoidosis.
• Dystrophic calcifications (greater than 5 mm, frequently including lymph nodes or pleura).
● Histology
• Alveolar wall fibrosis and thickening; lamellar, calcified microliths inside alveolar gaps;
• If there is insufficient sample, the biopsy may not be conclusive; nevertheless, an open lung biopsy is still decisive.
Protocol
● Problems Faced:
➣ The patient experienced increasing dyspnoea upon exertion;
➣ Imaging revealed diffuse micronodules with high density and ground-glass attenuation, suggesting calcifications;
➣ Histology from biopsies was inconclusive;
➣ Lung auscultation revealed coarse crackles, wheezing, and diminished vesicular sounds.
➣ A dismal prognosis may result from the disease's progressive and chronic nature.
➣ There is presently no effective medical treatment; in more severe instances, lung transplantation may be a possibility.
● Management and Nursing Interventions:
➣The diagnosis was made mainly on the basis of clinical and standard radiological findings from high-resolution CT and chest X-rays.
It is crucial to keep an eye on oxygenation, lung sounds, and respiratory status.
As needed, oxygen treatment is part of supportive care to maintain appropriate oxygen saturation.
➣ Cough and dyspnoea symptoms are managed.
➣ Nurses are essential in educating patients on the course of their diseases and how to report symptoms.
➣ It's crucial to keep an eye out for problems and functional impairment.
➣ Coordinating with interdisciplinary teams to provide patients with complete treatment, including respiratory therapy, and preparing them for potentially cutting-edge procedures like lung transplantation.
➣ psychological assistance as a result of the effects of a chronic, progressive sickness.
Notes
For more details visit 10.12659/AJCR.938456
