Pulmonary Mycobacterium abscessus: a canary in the cystic fibrosis coalmine.

We present a case of pulmonary nontuberculous mycobacterial infection (PNTM) with M. abscessus. After exclusion of genetic immune disorders known to cause NTM susceptibility, we found compound heterozygosity of two mutations, F508del and R117H in CFTR. The combination of F508del with a hypomorphic CFTR mutation can cause a mild Cystic Fibrosis (CF) phenotype with delayed CF symptoms in adulthood. Although the patient was continuously treated for her lung infection by different physicians for more than twenty years, the diagnosis CF had been missed. The forme fruste of CF should be considered in the analysis of host factors predisposing for PNTM.