Recurrent Isolated Pneumothorax Unveiling a Familial Multicystic Lung Disease in a 34-Year-Old Filipino Male

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Abstract INTRODUCTION: Spontaneous pneumothorax (SP) often occurs due to rupture of subpleural blebs or cysts, with an incidence of 1.2-7.4 cases/100,000. 11.5% exhibit familial predisposition. In resource-limited settings, genetic testing is often unavailable, prompting reliance on advanced imaging techniques to narrow differentials or establish a diagnosis. Here, we present a unique case of recurrent SP in a young male with multicystic lung disease with notable family history of pneumothorax. CASE: A 34-year-old Filipino male, eight pack-year smoker and illicit drug user, presented with a one-week history of worsening dyspnea and pleuritic chest pain. He had previously been admitted at age 24 for a pneumothorax, which resolved with conservative management. Family history was significant for a sibling who underwent surgical intervention for a pneumothorax one year prior. He denied bouts of respiratory infections, congenital connective tissue or lung disorders, skin lesions, or unusual skin elasticity. On examination, he was hypotensive (90/60 mmHg), tachycardic (101 bpm), and tachypneic (23 breaths per minute), with an oxygen saturation of 90% on room air. Decreased breath sounds and reduced vocal fremitus were noted on the right side, extending from the apex to the lower lung fields. A chest radiograph revealed a right-sided tension pneumothorax with mediastinal shift and large lucent lesions without lung markings in the left retrocardiac area (measuring 4.5 x 4.9 cm and 3.7 x 3.2 cm). A chest tube was placed, resolving the pneumothorax, as confirmed on repeat radiographs. Subsequent chest CT showed multiple variably-sized, thin-walled air cysts on both lungs, the largest in the left basal lower lobe, measuring 3.0 x 4.4 x 7.9 cm, near the mediastinum. Abdominal ultrasound excluded renal masses. Following pneumothorax resolution, he underwent pleurodesis and was discharged in stable condition. DISCUSSION: Diffuse cystic lung disease (DCLD) encompasses a broad spectrum of slowly progressing rare conditions but significant differential diagnosis and complications. A family history, distinctive clinical features, and specific radiographic findings can help guide the diagnosis. Familial DCLD with predominant lower-lobe, paramediastinal cysts and recurrent SP—such as in our patient—often points to Birt-Hogg-Dubé syndrome (BHD), a rare autosomal-dominant disorder associated with cystic lung disease, skin lesions, and renal tumors. BHD is thought to be rare, though its prevalence remains unknown, and studies suggest a 9% likelihood of BHD in patients presenting with SP. However, only 5% of male BHD patients present with isolated pneumothoraces, as in this case, emphasizing the variability in presentations of this intriguing syndrome.

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