Nasal polyposis in atypical cystic fibrosis: A case report

Cystic fibrosis (CF) is one of the most common inherited life-shortening diseases with an incidence of 1:2.500-3500 and a carrier frequency of 4-5% [1]. It is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, which encodes a protein expressed in the apical membrane of exocrine epithelial cells, resulting in changes to the fluid and electrolytes on cell surface. More than 1500 mutations have been described so far in the CFTR gene, grouped in 5 classes on the basis of the impact on protein synthesis or activity [2]. In the last years a mounting number of reports described patients that did not meet all diagnostic criteria for CF [4]; in particular, atypical or nonclassic CF is characterized by normal or borderline sweat test, pancreatic sufficiency and a monosymptomatic phenotype; the most studied forms are: congenital bilateral absence of vasa deferentes, acute or chronic recurrent pancreatitis, idiopathic bronciectasis [5]. These patients typically bear a severe and a mild (classes 4-5) CFTR mutation, the latter being dominant [6]. The involvement of upper airways is observed in up to 100% of classic CF patients, including recurrent sinusitis and rhinitis. Nasal polyps are present in 6-48% of overall CF patients and in 5-15.2% of less than 10 years old CF patients. Surgery is required for syntomatic polyps. It is the second most common class of operations performed on CF patients. In spite of the best of operations CF patients will have recurrence, because of systemic disease. We describe a patient diagnosed as "atypical CF" on the basis of persisting chronic rhinosinusitis, that showed a very rare CFTR genotype. (C) 2009 Elsevier Ireland Ltd. All rights reserved.