Background: Cystic fibrosis (CF) is the most common life-threatening
autosomal recessive disease among Caucasians, but is rare in the
African population. It usually presents with pulmonary (e.g. recurrent
infections) or gastrointestinal symptoms (e.g. failure to thrive). Over
1600 mutations located on chromosome 7 have been described with
great variability in clinical phenotype particularly in regard to onset,
progression, and severity of the disease.
Case report: We report the case of a 1 month old girl from a black
African mother and a Caucasian father who presented with a rash on
the cheeks and perineum. The rash consisted of exfoliative dermatitis
with erosive lesions and was resistant to local treatment. It then
progressed over the entire body. She developed diffuse edema and
hepatomegaly with poor weight gain. Laboratory investigations
demonstrated a normochromic normocytic anemia, hypoalbuminemia
and low zinc levels. Skin biopsy suggested dermatitis consistent with
a nutritional deficiency such as acrodermatitis enteropathica. Fecal
elastase was markedly decreased but unfortunately sweat testing
was not possible at this time due to the widespread dermatitis. Gastrointestinal
symptoms disappeared after introduction of pancreatic
enzymes, zinc and vitamin supplementation with rapid resolution
of the skin lesions. Sweat test performed later was clearly positive
(Chloride = 90 & 86 mmol/l). CFTR gene sequencing revealed a
compound-heterozygous genotype with F508del / T501l mutations;
the latter a new missense mutation in exon 10 not previously described
in the literature.
Conclusion: Cutaneous manifestations as the initial presentation
of CF are rare. They are almost always secondary to malabsorption,
therefore diminished fecal elastase as sign of exocrine pancreatic
insufficiency, is the investigation of choice. This is particularly
pertinent if the sweat test is not possible initially due to the condition
of the skin. Furthermore, we recommend gene sequencing analysis
to confirm the diagnosis where extended panel mutations have not
identified two common mutations. In our case we found a new
mutation for CF.