Interstitial pulmonary fibrosis and von Recklinghausen's disease. An ultrastructural and immunofluorescent study

RASopathies for Radiologists

RASopathies are a heterogeneous group of genetic syndromes caused by germline mutations in a group of genes that encode components or regulators of the Ras/mitogen-activated protein kinase (MAPK) signaling pathway. RASopathies include neurofibromatosis type 1, Legius syndrome, Noonan syndrome, Costello syndrome, cardiofaciocutaneous syndrome, central conducting lymphatic anomaly, and capillary malformation-arteriovenous malformation syndrome. These disorders are grouped together as RASopathies based on our current understanding of the Ras/MAPK pathway. Abnormal activation of the Ras/MAPK pathway plays a major role in development of RASopathies. The individual disorders of RASopathies are rare, but collectively they are the most common genetic condition (one in 1000 newborns). Activation or dysregulation of the common Ras/MAPK pathway gives rise to overlapping clinical features of RASopathies, involving the cardiovascular, lymphatic, musculoskeletal, cutaneous, and central nervous systems. At the same time, there is much phenotypic variability in this group of disorders. Benign and malignant tumors are associated with certain disorders. Recently, many institutions have established multidisciplinary RASopathy clinics to address unique therapeutic challenges for patients with RASopathies. Medications developed for Ras/MAPK pathway-related cancer treatment may also control the clinical symptoms due to an abnormal Ras/MAPK pathway in RASopathies. Therefore, radiologists need to be aware of the concept of RASopathies to participate in multidisciplinary care. As with the clinical manifestations, imaging features of RASopathies are overlapping and at the same time diverse. As an introduction to the concept of RASopathies, the authors present major representative RASopathies, with emphasis on their imaging similarities and differences. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Neurofibromatosis type 1 and pneumoconiosis: A case report on a coincidence

Neurofibromatosis (NF) is a neurocutaneous syndrome characterized by the development of central or peripheral nervous system tumors. The most common form, known as NF1 or Von Recklinghausen's disease, presents with distinct clinical features, including cutaneous and ocular manifestations, along with various other organ and systemic symptoms. While the lung findings associated with neurofibromatosis lack specificity, they can include parenchymal cysts and bullae formation, primarily in the upper-apical regions. Additionally, progressive fibrotic changes, such as ground-glass areas, consolidations, and paving stone patterns, may manifest in the basal parts of the lungs. In this case report, a case of NF1 diagnosed in adulthood and accompanying pneumoconiosis was discussed as a coincidence.

Neurofibromatosis type 1: evaluation by chest computed tomography

Objective

The aim of this study was to evaluate chest computed tomography (CT) findings in patients diagnosed with neurofibromatosis type 1 (NF1).

Material and Methods

This was a retrospective study in which we reviewed the chest CT scans of 14 patients diagnosed with NF1 and neurofibromatosis-associated diffuse lung disease (NF-DLD). The sample comprised eight women and six men. The median age was 55 years (range, 11-75 years). The diagnosis of NF1 was made on the basis of the diagnostic criteria established by the U.S. National Institutes of Health. The images were analyzed by two chest radiologists, who reached decisions by consensus.

Results

The predominant CT finding of NF-DLD was multiple cysts, which were observed in 13 patients (92.9%), followed by emphysema, in eight (57.1%) and subpleural bullae, in six (42.9%). Other findings included subcutaneous neurofibromas, in 12 patients (85.7%), ground-glass opacities, in one (7.1%), and tracheobronchial neurofibromas, in one (7.1%). The pulmonary abnormalities were bilateral in 12 cases (85.7%). The abnormalities were predominantly in the upper lung fields in eight cases (57.1%), and their distribution was random in 11 (78.6%).

Conclusion

Pulmonary cysts, emphysema, and subpleural bullae appear to be the chest CT findings that are most characteristic of NF-DLD.

Phenotype and Outcomes of Pulmonary Hypertension Associated with Neurofibromatosis Type 1

Rationale: Pulmonary hypertension (PH) associated with neurofibromatosis type 1 (NF1) is a rare and largely unknown complication of NF1.Objectives: To describe characteristics and outcomes of PH-NF1.Methods: We reported the clinical, functional, radiologic, histologic, and hemodynamic characteristics, response to pulmonary arterial hypertension (PAH)-approved drugs, and transplant-free survival of patients with PH-NF1 from the French PH registry.Measurements and Main Results: We identified 49 PH-NF1 cases, characterized by a female/male ratio of 3.9 and a median (minimum-maximum) age at diagnosis of 62 (18-82) years. At diagnosis, 92% were in New York Heart Association functional class III or IV. The 6-minute-walk distance was 211 (0-460) m. Pulmonary function tests showed low Dl_CO (30% [12-79%]) and severe hypoxemia (Pa_O2 56 [38-99] mm Hg). Right heart catheterization showed severe precapillary PH with a mean pulmonary artery pressure of 45 (10) mm Hg and a pulmonary vascular resistance of 10.7 (4.2) Wood units. High-resolution computed tomography images revealed cysts (76%), ground-glass opacities (73%), emphysema (49%), and reticulations (39%). Forty patients received PAH-approved drugs with a significant improvement in functional class and hemodynamic parameters. Transplant-free survival at 1, 3, and 5 years was 87%, 54%, and 42%, respectively, and four patients were transplanted. Pathologic assessment showed nonspecific interstitial pneumonia and major pulmonary vascular remodeling.Conclusions: PH-NF1 is characterized by a female predominance, a low Dl_CO, and severe functional and hemodynamic impairment. Despite a potential benefit of PAH treatment, prognosis remains poor, and double-lung transplantation is an option for eligible patients.

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.

Neurofibromatosis type-1-associated diffuse lung disease in children

OBJECTIVE

The purpose of the study was to investigate the occurrence of diffuse lung disease associated with neurofibromatosis type-1 in the pediatric population. We also aimed at evaluating computed tomography (CT) findings of the disease.

INTRODUCTION

Diffuse lung disease associated with neurofibromatosis type-1 has been described mainly in the adult population; causes and connections between lung disease and the genetic disorder are still not completely understood. The occurrence of the disease in non-smokers, the presence of blebs, bullae or cysts distinct from smoking-related emphysema on CT and the histopathological pattern characterized by lymphoplasmocytic inflammation and fibrosis, are all factors that support the association of diffuse lung disease as a distinct manifestation of neurofibromatosis.

METHODS

We retrospectively reviewed, with "lung window," all the spinal CTs performed in two institutions from 2004 to 2018 for scoliosis assessment in pediatric patients affected by neurofibromatosis type-1 (group 1). Moreover, we retrospectively analyzed a control group of pediatric patients, affected by severe scoliosis without neurofibromatosis (group 2). Differences between the two groups were analyzed to ascertain whether the disease can be related to neurofibromatosis type-1 rather than to scoliosis.

RESULTS

Six out of thirty one subjects from group 1 (19.4%) showed a condition of diffuse lung disease while none (0 of 31) in group 2. The differences between the two groups were statistically significant (P = .01). All six patients showed subpleural blebs, bullae, or cysts without basilar fibrosis.

CONCLUSION

Our research consolidates the hypothesis that diffuse lung disease is a direct manifestation of neurofibromatosis type-1 and that early onset is possible, even in pediatric patients.

Neurofibromatosis type 1: State-of-the-art review with emphasis on pulmonary involvement

Neurofibromatosis type 1 (NF-1), also known as von Recklinghausen's disease, is an autosomal dominant dysplasia of the ectoderm and mesoderm with a variable clinical expression, but near-complete penetrance before the age of 5 years. The estimated incidence is 1 in 3000 births. NF-1 is characterized by collections of neurofibromas, café-au-lait spots, axillary and inguinal freckling, and pigmented hamartomas in the iris (Lisch nodules). Pulmonary manifestations of NF-1, which usually include bilateral basal reticulations and apical bullae and cysts, are reported in 10-20% of adult patients. Clinically, neurofibromatosis-associated diffuse lung disease (NF-DLD) usually presents with nonspecific respiratory symptoms, including dyspnea on exertion, shortness of breath, and chronic cough or chest pain, at the time of diagnosis. Computed tomography (CT) is highly accurate for the identification and characterization of NF-DLD; it is the most reliable method for the diagnosis of this lung involvement. Various CT findings of NF-DLD, including cysts, bullae, ground-glass opacities, bibasilar reticular opacities, and emphysema, have been described in patients with NF-1. The typical CT pattern, however, is characterized by upper-lobe cystic and bullous disease, and basilar interstitial lung disease. Currently, the goal of NF-DLD treatment is the earliest possible diagnosis, focusing on symptom relief and interventions that positively alter the course of the disease, such as smoking cessation. The aim of this review is to describe the main clinical, pathological, and imaging aspects of NF-1, with a focus on pulmonary involvement.

Pulmonary hypertension associated with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1), also known as von Recklinghausen disease, is a frequent autosomal dominant genetic disorder with a prevalence of 1 in 3000. Pulmonary hypertension (PH) associated with NF1 (PH-NF1) is a rare but severe complication of NF1 and is classified as Group 5 PH, defined as “PH with unclear and/or multifactorial mechanisms”. A literature review in PubMed on the association between NF1 and PH identified 18 articles describing 31 cases. PH-NF1 was characterised by a female predominance, an advanced age at diagnosis, an association with parenchymal lung disease in two out of three cases and poor long-term prognosis. NF1 is generally associated with interstitial lung disease but some cases of severe PH without parenchymal lung disease suggest that there could be a specific pulmonary vascular disease. There is no data available on the efficacy of specific pulmonary arterial hypertension treatment in PH-NF1. Therefore, these patients should be evaluated in expert PH centres and referred for lung transplantation at an early stage. As these patients have an increased risk of malignancy, careful assessment of the post-transplant malignancy risk prior to listing for transplantation is necessary. Clinical trials are needed to evaluate promising treatments targeting the RAS-downstream signalling pathways.

Pulmonary hypertension is a rare but severe complication of neurofibromatosis type 1. There are no data about the efficacy of specific PAH treatment in this disease and lung transplantation should be discussed at an early stage.http://ow.ly/JMU030lezfY

Pulmonary hypertension in neurofibromatosis

Two cases of severe pulmonary arterial hypertension in patients with neurofibromatosis are reported. The published research is reviewed. In conclusion, it is suggested that the association between these conditions be recognized in the classification of pulmonary hypertension.

Lack of evidence for an association between neurofibromatosis and pulmonary fibrosis

STUDY OBJECTIVES

To reassess the association between neurofibromatosis and pulmonary fibrosis.

DESIGN

Retrospective single-center study with analysis of patients' chest radiographs, CT scans, and medical records.

SETTING

Tertiary care, referral medical center.

PATIENTS

One hundred fifty-six adult patients with neurofibromatosis seen over a 6-year period between 1997 and 2002.

RESULTS

A review of chest radiographs revealed abnormal findings in 70 patients (44.9%). The most common radiographic abnormalities were extrapulmonary nodules or masses seen in 22 patients (14.1%), followed by skeletal abnormalities in 16 patients (10.3%). Bilateral interstitial infiltrates were noted in only three patients (1.9%), all of whom had potential causes other than neurofibromatosis for their lung infiltrates, including smoking-related interstitial lung disease, rheumatoid lung disease, recurrent pneumonias, and a history of ARDS. CT scans were available in two of these patients and revealed nonspecific patterns of abnormalities with no honeycombing. Six patients had bullae or cystic airspaces demonstrated on chest radiography or CT scan; all of these findings occurred in the context of smoking-related emphysema. Combined together, bilateral interstitial lung infiltrates or cystic airspaces were demonstrated in five patients (3.2%) by chest radiography, and in eight patients (5.1%) by chest radiography or CT scanning; one patient had both findings on the CT scan.

CONCLUSIONS

We found little evidence to support an association between neurofibromatosis and pulmonary fibrosis or any other form of parenchymal lung disease. Interstitial lung disease and bullae described in association with neurofibromatosis in previous reports may have, in part, represented smoking-induced manifestations.

Prevalência de achados radiográficos da neurofibromatose tipo 1: estudo de 82 casos

A neurofibromatose tipo 1 é uma das enfermidades genéticas mais comuns da espécie humana com padrão de herança autossômica dominante. As alterações radiológicas encontradas com maior freqüência são: escoliose, cifose, cifoescoliose, áreas de erosão óssea, crescimento anormal do osso, pseudo-artrose, meningocele, deformidade da parede posterior dos corpos vertebrais ("scalloping"), peito escavado, lesões osteolíticas nos ossos longos e alterações do sistema nervoso central. Os autores apresentam dados estatísticos dos achados radiográficos prevalentes em 82 pacientes com neurofibromatose tipo 1 acompanhados pelo Centro de Pesquisa e Atendimento em Neurofibromatose, de São José do Rio Preto, SP, um centro multidisciplinar de estudo e tratamento dos portadores da doença.

Pulmonary hypertension and interstitial fibrosis in von Recklinghausen neurofibromatosis

Neurofibromatosis von Recklinghausen (NFvR) has been reported to be associated with diffuse interstitial pulmonary fibrosis. We describe a patient with NFvR presenting in middle age with dyspnea and cyanosis. Chest radiographs showed right ventricular enlargement, dilated proximal pulmonary arteries, and bilaterally increased interstitial markings. Cardiac catheterization showed moderately severe pulmonary hypertension and no evidence of congenital heart defect. The interstitial fibrosis associated with NFvR can result in symptomatic pulmonary hypertension.