Frequency of aquagenic palmoplantar keratoderma in cystic fibrosis: a new sign of cystic fibrosis?

BACKGROUND: Aquagenic palmoplantar keratoderma (APPK), also known as aquagenic wrinkling of the palms, is characterized by oedema of palms and/or soles, whitish papules, hyperwrinkling and sometimes pruritus or pain after water immersion. Its frequency in the general population is unknown. About 40 cases have been reported to date, including some among patients with cystic fibrosis (CF) or CF heterozygotes. OBJECTIVES: To determine the frequency of APPK among patients with CF. METHODS: Twenty-seven patients from the Centre of Competence on Cystic Fibrosis of Roscoff were examined by a dermatologist after immersion of the palms in water for 2-3 min. RESULTS: The frequency of APPK was 41% (11 of 27 patients). Some patients had not previously noticed the lesions. The frequency was higher among inpatients than outpatients. We suspect that occlusion (caused by the gloves worn by inpatients) can explain this difference. The number of patients included in this study is not sufficient to draw any conclusions concerning the type of CF mutation and its impact on the frequency of APPK. CONCLUSIONS: APPK is frequent among patients with CF and, thus, should be considered a sign of CF. APPK is underdiagnosed because physicians usually do not look for it. CF screening should be considered for any patient presenting with these symptoms, followed by genetic counselling if necessary.

Evaluation of quantitative PCR for early diagnosis of Pseudomonas aeruginosa infection in cystic fibrosis: a prospective cohort study.

OBJECTIVES: Early detection of Pseudomonas aeruginosa lung positivity is a key element in cystic fibrosis (CF) management. PCR has increased the accuracy of detection of many microorganisms. Clinical relevance of P. aeruginosa quantitative PCR (qPCR) in this context is unclear. Our aim was to determine P. aeruginosa qPCR sensitivity and specificity, and to assess the possible time saved by qPCR in comparison with standard practice (culture). METHODS: A multicentre cohort study was conducted over a 3-year period in 96 patients with CF without chronic P. aeruginosa colonization. Sputum samples were collected at each visit. Conventional culture and two-step qPCR (oprL qPCR and gyrB/ecfX qPCR) were performed for 707 samples. The positivity criteria were based on the qPCR results, defined in a previous study as follow: oprL qPCR positivity alone if bacterial density was <730 CFU/mL or oprL qPCR combined with gyrB/ecfX qPCR if bacterial density was ≥730 CFU/mL. RESULTS: During follow up, 36 of the 96 patients with CF were diagnosed on culture as colonized with P. aeruginosa. This two-step qPCR displayed a sensitivity of 94.3% (95% CI 79.7%-98.6%), and a specificity of 86.3% (95% CI 83.4%-88.7%). It enabled P. aeruginosa acquisition to be diagnosed earlier in 20 patients, providing a median detection time gain of 8 months (interquartile range 3.7-17.6) for them. CONCLUSIONS: Implementing oprL and gyrB/ecfX qPCR in the management of patients with CF allowed earlier detection of first P. aeruginosa lung positivity than culture alone.