Neurofibromatosis-Associated Diffuse Lung Disease: A Case Report and Review of the Literature

Neurofibromatosis-1 or von Recklinghausen's disease is an autosomal dominant disorder. Cafe au lait macules are generally the initial presenting feature of the disease, and there can be varying degrees of involvement of the skeletal, neurological, and pulmonary organ systems as the disease progresses. The existence of neurofibromatosis-associated diffuse lung disease (NF-DLD) as a separate entity has always been questioned and, is often attributed to cigarette smoking, rather than a manifestation of NF-1. A 59-year-old male with a history of neurofibromatosis presented with shortness of breath and ataxia for 10 days. Exam findings were pertinent for tachycardia, tachypnea, and diffuse cutaneous neurofibromas. Workup showed white blood count (WBC) of 15.9 k/ul, electrocardiogram with biatrial enlargement and right axis deviation, and a chest X-ray showed left lower lobe infiltrate concerning for pneumonia. Computed tomography (CT) scan of the chest revealed left basilar consolidation with surrounding ground-glass opacities and innumerable bilateral thin-walled cysts. The latter finding raised suspicion for NF-DLD. The patient was evaluated by pulmonology with recommendations to continue treatment for pneumonia and follow-up with high-resolution CT of the chest and complete pulmonary function testing in 12 weeks. He was discharged in a stable condition after five days of hospitalization. NF-DLD is a pulmonary manifestation of NF-1 with non-specific respiratory symptoms and a characteristic pattern of upper lobe cystic and basilar interstitial lung disease. It usually presents in the 4th or 5th decade, earlier in tobacco users, but a few pediatric cases have also been reported. The presentation of NF-DLD can be variable, ranging from dyspnea, chest pain, chronic cough, hemoptysis, or an incidental finding on CT. Multiple complications, including spontaneous pneumothorax due to the rupture of subpleural blebs, pulmonary hypertension, and chronic respiratory failure, are associated with NF-DLD. NF-DLD can be prevented by smoking cessation but, there are no known modalities for treatment; however, complications can be managed symptomatically. This case illustrates the diagnostic challenge that NF-DLD represents to clinicians. The patient's CT from two years ago showed emphysematous changes along with scattered fibrosis and scarring, and no cystic changes were mentioned, unlike his latest CT, which showed innumerable cysts. This patient had a history of smoking, which likely put him at a higher risk for the development of cysts. However, he quit smoking 10 years prior, which suggests that his lung changes are not secondary to cigarette smoke, further confirming our suspicion for NF-DLD. Although routine screening is not implemented due to the rarity of the disease, NF-DLD should not be ruled out in patients with NF-1 presenting with pulmonary symptoms until a high-resolution computed tomography (HRCT) is obtained.

Keywords: cystic lung disease; neurofibromatosis associated diffuse lung disease; nf-1; nf-dld.