Neurofibromatosis (NF) is one of the diseases of the phacomatosis family. The incidence of the common subtype NF1 ranges between 1:2’300–1:3’000. About half of the cases are familial with an autosomal dominant inheritance, the rest are due to spontaneous mutations. Consequences are dyplasia of ecto- and mesoderm. Diagnostic criteria are café-au-lait maculas, neurofibromas, etc. Although thoracic manifestations are diverse and quite common, the involvement of lung parenchyma in NF1 appears to be rare. Studies report a prevalence of interstitial lung disease in 1.9–20% of NF1.
Two cases are reported and compared with the literature.
Case 1: 56-yr. old man, never-smoker, with shortness of breath at rest. NF1 first diagnosed 1990 on appearance of café-au-lait maculas and cutaneous and subcutaneous neurofibromas. In 2005 parenchymal lung involvement was diagnosed with fibrocytic and interstitial lung manifestations in chest-CT. Severe pulmonary hypertension (PH) with systolic pressure of 80mmHg was also found. Congenital-resistance against activated protein C was detected, which can cause recurrent thromboembolism, also leading to PH. Case 2: 69-yr.old man, ex-smoker, 20 packyears, with crackles over the lungs. The patient suffered from pulmonary tuberculosis in 1977. Diagnosis of NF1 based on café-au-lait maculas and subcutaneous neurofibromas. Chest x-ray showed diffuse parenchymal abnormalities, mostly in both upper lobes. Further tests showed a moderate obstructive lung disorder and moderate hypoxemia.
A search of the literature implies that lung involvement is an uncommon manifestation of NF1. Our assumption is, that the actual frequency of pulmonary manifestations is probably overestimated, since parenchymal abnormalities in NF1 are difficult to differentiate from other lung disorders. The diagnosis of lung involvement in NF1 is often based on CT-morphology combined with extra-pulmonary stigmata. Specific histological or characteristic bronchoalveolar patterns are unknown. Our second case illustrates these difficulties: the described parenchymal abnormalities could also be smoking-related and/or due to tuberculosis.
For prognostic reasons, differentiation from other lung disorders is important, especially from idiopathic interstitial pneumonias and in particular from the prognostically worse idiopathic pulmonary fibrosis.
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