We report a case of a 43 years old, Namibian female, with Mounier-Kuhn syndrome and a background of HIV infection. The aetiology of MKS is generally unclear, although genetic predisposition to congenital tracheobronchomegaly, as well as environmental factors are thought to play a role. Familial recessive inheritance has been reported, but possible secondary causes or associations with various connective tissue disease including Ehlers-Danlos syndrome, Marfan s syndrome, ataxia-telangiectasia, Bruton-type agammaglobulinemia, ankylosing spondylitis, cutis laxa and light chain deposition disease have also been described. This patient had no relatable family history. She had a negative screen for connective tissue diseases and a normal autoimmune profile. The diagnosis of MKS can be based on clinical as well as chest X-ray and CT scan findings (gold standard). The airway measurements highlighted in Table 1 are diagnostic. CT scan findings are varied and help to provide a staging system for MKS. The radiological society has described three stages of MKS as follows: Type 1: minimal symmetrical dilatation; Type 2: pronounced tracheal dilatation and diverticula; Type 3: marked tracheal and bronchial dilatation and diverticular extending until distal bronchi bilaterally.
The diagnosis of such a rare condition can be challenging in our setting, due to multiple factors. Limited access to CT imaging can be considered an important factor in the delay of diagnosis. The north of Namibia, which hosts approximately 60% of the population, currently has three CT scan machines available; one in the state sector and two in the private sector, of which our hospital, Ongwediva Medipark, hosts one. Also, limited access to pulmonology services - such as bronchoscopy, which aid in confirming this diagnosis again - contributes to this delay. During the time of investigating this case, the whole of Namibia had one pulmonologist based in the capital city of Windhoek. We entertained a range of differential diagnoses during workup including chronic obstructive airways disease, bronchiectasis, pulmonary tuberculosis, connective tissue disorders; some of which were ruled out with investigations described and did not explain the case findings in their entirety. Another factor is that, in the setting of HIV infection, one may be more inclined towards investigating and diagnosing the commonly seen respiratory infections and disregarding a more thorough investigative approach.
The pulmonary manifestations of HIV infection have been well described in literature. Cases reported so far of MKS in individuals with HIV infection seem to have other possible confounding risk factors such as tobacco and recreational drug use, as noted by Fletcher et al.. Another case report described MKS in a patient that had profound immunosuppression with a CD4 count of 3cells/mm3. These additional factors were not present in our case and this could perhaps account for the comparatively mild type of MKS seen. Krustins et al. in their review, listed HIV infection as one of the conditions that is most likely to be a separate entity if occurring concurrently with MKS. Other conditions listed in this category include malignancies, adrenal insufficiency and end stage renal failure among others. Our patient was virologically suppressed with a good CD4 cell count, therefore, it seems unlikely that underlying HIV infection would be the sole cause of her recurrent infections. Other associations between MKS and HIV have yet to be conclusively described and further study may be required in this regard. MKS can cause significant morbidity and negatively impact the quality of life of a patient.
Diagnostic delays may lead to a patient developing more severe disease, with irreversible lung fibrosis and worsening respiratory failure. Once the diagnosis is established, specific measures that have been proven to reduce progression and morbidity can be offered in a timely manner. These include; effective treatment of infections, positive airway pressure, use of mucolytic agents and chest physiotherapy aimed at aiding mucus clearance. Pneumococcal and influenza vaccines are recommended for these patients. The usefulness of prophylactic antibiotics in this regard is yet to be determined. Surgical options, such as airway stenting and tracheobronchoplasty, have proven to be useful in some more severe cases. Our patient benefitted from positive airway pressure management and adjuvant therapy as described above and did not require any surgical interventions. A year after her diagnosis and appropriate management, she objectively reports fewer respiratory tract infections. She follows up with the pulmonologist every 6 months.