Pulmonary Hypoplasia : A Rare Cause of Chronic Cough in TB Endemic Area

Pulmonary hypoplasia is a rare disease characterized by a defect of lung development more often unilateral. The diagnosis requires several exams to eliminate other causes of pulmonary retraction. We report two cases at the department of pneumophtisiology of the University Teaching Hospital of Point G. The first case is a young adult who was complaining of a chronic cough. Etiological investigation required several exams including spirometry and Computed tomographic scan (CT scan). After elimination of all suspected causes of pulmonary opacity, the diagnosis of pulmonary hypoplasia was retained. The second case is a 2-year-old girl who was born with congenital cardiopathy whose respiratory complications were increasing during her childhood and respiratory explorations discovered pulmonary agenesis. Pulmonary hypoplasia is rare in our medical practice, but attention must be drawn to a retractile pulmonary opacity in young age after elimination of all infectious causes in TB endemic area.


Introduction
Pulmonary hypoplasia (PH) is a rare congenital malformation without apparent cause associated with other developmental abnormalities [1].It is defined as a defect in the lungs characterized by bronchial segmentation often conserved in a Open Journal of Respiratory Diseases decrease in pulmonary alveoli.It may be unilateral or bilateral, segmental or lobar [2].The Pulmonary hypoplasia occurs with an alteration of the molecular mechanisms of the early diaphragm and lung development, aggravated by later fetal dynamic stress [3].The majority of children with pulmonary hypoplasia will have some degree of pulmonary artery hypertension resulting from increased muscularization of the intra acinar pulmonary arteries [4].With an incidence estimated to be 1 per 10,000 births, 24% of malformations are discovered at birth or adolescence, resulting in significant morbidity and mortality [5].Mortality is particularly due to congenital cardiac anomalies, but also esophageal, vertebral and renal [2].A hypoplastic lung is more likely to be atelectasis, fibrostic, functionless, and prone to infection whatever is the etiology.The typical presentation is neonatal respiratory distress syndrome, whereas the diagnosis in adulthood is usually fortuitous or secondary to respiratory symptoms [6] [7].Cough is the most common respiratory symptom in hypoplasia [7] [8] [9] [10].It is qualified to be chronic and suspecting tuberculosis (TB) if it exceeds fifteen (15) days according to the national TB program (PNLT) guidelines in Mali.TB incidence in Mali is 57 per 100,000 populations; TB screening strategy is based on cough duration.A chronic cough is a major criterion for TB test in sputum in Mali and all country where TB is endemic [11].We report two cases of pulmonary hypoplasia fortuitously discovered at the Department of pneumophtisiology of the University Teaching Hospital of Point G in Bamako, Mali.These cases are the first to be published in Mali; their diagnosis was derived from collaborative teamwork between the clinicians and radiologists.

Observation
Observation 1: A 24 years old, male, farmer, and tailor with no alcohol and smoking history.He was received at pneumology consultation for a chronic cough with mucopurulent expectoration sometimes fetid.He was presenting Sadoul stage-2 dyspnea for seven (7) years associated with chest pain, heartburn, mild to moderate persistent rhinitis and recurrent cough worsened since 1 month.Physical examination found a low-grade fever of 38˚C, a static performance (PS) of 1, a body mass index (BMI) of 20 kg/m 2 , an absence Digital clubbing, the respiratory frequency was 23 cycles/minutes at rest, and oxygen saturation (SpO 2 ) was 97% at ambient air.Cardiac auscultation was normal.At Chest inspection noted a diminution of the right chest expansion.Pulmonary auscultation found a decreased vesicular murmur at the right side, cracking rales at bottom of the lung and bilateral rhonchi and wheezes located at the third section of the right lung.
Chest X-ray showed a dense opacity of the right middle lobe, trachea and mediastinal displacement to the right, inter-costal spaces pinching on the right lung and distention of the left lung (Figure 1(a)).The blood cell count was normal, the serology of the acquired immunodeficiency virus (HIV) was negative and tuberculin skin test (TST) was positive (12 mm).Smear Acid Fast Bacilli test was negative with Ziehl Nielsen coloration and absence of Mycobacterium tuberculosis

Discussion
Congenital pulmonary malformations are rare and complex.Most of them are discovered prenatally in developed countries or during the first month of life, but late discovery is also frequent depending on the severity of the symptoms [2].The majority of malformations originate between 4 and 16 weeks of pregnancy, during the development of the aerial tree [12].They are classified in 3 types according to Schneider: type 1 is pulmonary agenesis (complete absence of bronchus and parenchyma), type 2 is pulmonary aplasia (rudimentary blind bronchus with no parenchyma), and type 3 is pulmonary hypoplasia (incomplete bronchial development and varying degrees of parenchyma) [4].Our patients respond to type 3, which would be secondary to the mechanical compression of the homolateral lung by intra-abdominal organs that remained in the thoracic position, the absence of regulation of the intra-pulmonary fluid and the oligoamnios are involved in the genesis of pulmonary hypoplasia [3] [12] [13].
It more often unilateral and can affect regardless of ages.Their frequency varies between 1/10,000 and 1/200,000 birth seems to be underestimated [14].The clinical diagnosis remains difficult because there are no clinical symptoms or signs characteristic of pulmonary agenesis [6].The circumstances of discovery of pulmonary agenesis reported in the literature are multiple, sometimes accidental during a medical checkup [15], investigation of a chronic cough or chest pain in a teenager or an adult [7] [8], investigation for respiratory distress or stunted growth during the first days of life, confirming the congenital aspect of the disease [16].A discrete male predominance is reported authors [17] or equal frequency regardless of gender [7] as found in our series.The literature review found an inconsistent predominance of the left side in 70% which seems to be less associated with cardiac abnormalities [9] [14].In our series, we reported both attaint left and right side.The cardiac anomaly was associated with left pulmonary hypoplasia in our second observation.Physical signs such as chest asymmetry, diminution of chest expansion, chronicity of symptoms and images chest X-ray in our context raise the discussion of lung destruction post-infection especially tuberculosis.The ventilatory compensation at the expense of the vascularization compensation would explain the occurrence of PAH.It was asso-Open Journal of Respiratory Diseases ciated with agenesis in 19% of cases and in 88% if there is a cardiac malformation [16] [18].That could explain the precocity in one of our cases that has a TAC.The occurrence of primary pulmonary hypoplasia is rare and seems to be of low symptomatic character before puberty, as found in our series.The presence of comorbidities has a negative impact on prognosis [17] [19].
Suspicion is made on chest radiography and the confirmation requires several complementary exams to eliminate infectious etiology such as tuberculosis squeals, trachea-bronchial obstacles.Thoracic T Scan is a key element for certainty diagnosis.It helps to visualize bronchial, parenchyma and vascular abnormalities [1] [7] [8] [17].The pulmonary functional assessment, in particular, the spirometry was performed in one of our cases and revealed a mixed ventilatory disorder.A similar result has been reported by Abdelfatah [8].Lung scintigraphy can estimate the functional contribution of the lung; it was not feasible in our context because of the lack of technical platform [15].
The treatment is essentially symptomatic in the absence of surgical indication as described in the literature [1].The emphasis was placed on medical treatment associating physiotherapy for bronchial drainage, pneumococcal vaccination, nasal hygiene, and bronchodilators.The treatment has improved the quality of life of our patients by reducing the frequency of exacerbations and patients' tolerance to the effort.

Conclusion
Pulmonary hypoplasia remains a rare diagnosis in our medical practices.It is under-diagnosed or/and the delay would be explained to its scarcity and nonspecificity of the symptoms.It must be investigated in any chronic respiratory infections associated with unilateral chest opacity or diminution of lung volume at chest X-ray.The realization of the scanner is necessary to differentiate tuberculosis sequelae in low-income countries endemic.