J84.02 Pulmonary alveolar microlithiasis

Name of the Condition

• Pulmonary alveolar microlithiasis

Summary

Pulmonary alveolar microlithiasis is a rare lung condition characterized by the accumulation of calcium phosphate microliths (tiny stones) within the alveoli (air sacs) of the lungs. This buildup can impair gas exchange and respiratory function over time, though the disease may progress slowly or remain asymptomatic for years. The condition is often identified incidentally on imaging, as symptoms may be mild or absent in early stages.

Causes

The exact cause of pulmonary alveolar microlithiasis is not fully understood, but it is believed to involve genetic factors, as the disease has been associated with mutations in the SLC34A2 gene, which plays a role in phosphate transport. The microliths form due to abnormal calcium and phosphate metabolism within the alveoli, leading to their deposition over time.

Risk Factors

• Genetic predisposition (mutations in the SLC34A2 gene).
• Family history of the condition, suggesting an autosomal recessive inheritance pattern.
• No known environmental or lifestyle risk factors have been consistently identified.

Symptoms

• Shortness of breath (dyspnea), which may worsen with activity.
• Persistent dry cough.
• Chest discomfort or tightness.
• Fatigue and reduced exercise tolerance.
• In advanced cases, respiratory failure or cor pulmonale (right-sided heart failure due to lung disease) may occur.

Diagnosis

Diagnosis typically involves a combination of clinical evaluation, imaging studies (e.g., chest X-ray or CT scan), and sometimes lung biopsy. Imaging often reveals characteristic "sandstorm lung" appearance with diffuse, fine nodular opacities. Pulmonary function tests may show restrictive or obstructive patterns, and blood tests may assess calcium and phosphate levels.

Treatment Options

There is no specific cure for pulmonary alveolar microlithiasis. Management focuses on monitoring disease progression and addressing symptoms. Treatment may include:

• Oxygen therapy for hypoxemia (low blood oxygen).
• Pulmonary rehabilitation to improve exercise tolerance.
• In severe cases, lung transplantation may be considered.

Prognosis and Follow-Up

The prognosis varies, with some individuals remaining stable for years while others experience progressive lung damage. Regular follow-up with imaging and pulmonary function tests is recommended to monitor disease progression. Early detection and management can help mitigate complications.

Complications

• Progressive respiratory failure.
• Cor pulmonale (right-sided heart failure).
• Increased risk of respiratory infections due to impaired lung function.
• In rare cases, lung cancer has been reported, though the association is not well established.

Lifestyle & Prevention

No specific preventive measures are known, as the condition is genetic. Avoiding smoking and minimizing exposure to respiratory irritants may help preserve lung function. Regular medical check-ups are advised for those with a family history.

When to Seek Professional Help

Seek medical attention if you experience worsening shortness of breath, persistent cough, or chest pain, especially if you have a known family history of the condition. Early evaluation can help manage symptoms and monitor for complications.

Tips for Medical Coders

When coding for pulmonary alveolar microlithiasis (J84.02), ensure documentation supports the diagnosis, including imaging findings and clinical symptoms. Note that this code is specific to the condition and should not be confused with other interstitial lung diseases. Verify that the code aligns with the patient’s clinical presentation and diagnostic workup.