Pneumothorax, Primary Spontaneous

Alternative Names

  • PSP
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WHO-ICD-10 version:2010

Diseases of the respiratory system

Other diseases of pleura

OMIM Number

173600

Mode of Inheritance

Autosomal dominant with incomplete penetrance

Gene Map Locus

17p11.2

Description

A pneumothorax is a condition where the lung collapses on itself. This occurs due to air leaking into the cavity between the lungs and the chest wall pushing on the outside of the lung, causing it to collapse. There are varied types of pneuomothorax. The primary spontaneous pneumothorax (PSP) is one that occurs in the absence of any traumatic chest injury or known lung disease. It is usually precipitated by the rupture of a cyst or bleb on the lung surface. The characteristic symptom of PSP is a sharp chest pain of sudden onset leading to a tight feeling in the chest. The pain may radiate to the shoulder and increase with breathing in. Other signs and symptoms could include a sudden shortness of breath, rapid heart rate and breathing, cyanosis, cough, anxiety, and general fatigue. The annual incidence of PSP worldwide is estimated to be 18-28 and 1.2-6.0 per 100,000 males and females, respectively. Evidently, males have a higher risk for developing a PSP. Tall and thin men are at a higher risk. Other risk factors include smoking, age between 20 and 40 years, and having a family history of the condition.

A simple examination with a stethoscope is likely to give decreased or absent breath sounds over the affected lung in the case of a pneumothorax. Radiological examination confirms the diagnosis. A minor pneumothorax usually resolves on its own, without any medical intervention. More severe cases might require aspirating or removing the leaked air. In cases, where the leak does not spontaneously close, a chest surgery may be required. Individuals who have once developed a PSP have up to 40% chance of experiencing a recurrence within the next two years.

Studies of familial cases of PSPs have shed some light on the genetic basis of the condition. Some families have clearly shown an X-linked mode of transmission, whereas some show an autosomal dominant transmission with incomplete penetrance of 50% in males and 35% in females. The only gene known to be associated with PSP is the FLCN gene on chromosome 17p, which codes for the folliculin tumor suppressor protein. It is not clear, however, how mutations in this gene could influence the development of pneumothorax.

Epidemiology in the Arab World

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Other Reports

Kuwait

El Sonbaty et al. (2000) studied the characteristics of primary spontaneous pneumothorax in Arabs over 10 years of age and who were admitted in years 1985-1996 at Al-Ahmadi Governorate in Kuwait. Primary spontaneous pneumothorax was rare in female Arabs. There were only two females, hence leading to an incidence of 0.3 per 100,000 per year. Incidence in male Arabs was 8.8 per 100,000 per year. Smoking, a tall, asthenic (slim, relatively weak in appearance, ectomorphic) body build, and a positive family history were the most important risk factors associated with the condition.

Ayed et al. (2006a) prospectively compared the macroscopic and histological findings in 94 patients (81 male, 13 female) with primary spontaneous pneumothorax in Kuwait who underwent video-assisted thoracoscopic surgery (VATS). The surgery was successful in all cases, and in all, pathomorphologic changes were observed. The actual site of air leakage was observed in 26% of patients during surgery and in 21% with microscopic examination. Furthermore, Ayed et al. (2006b) conducted a study to understand the risk factors associated with spontaneous pneumothorax in Kuwait. Of the 254 patients recruited in the study, 71% were Kuwaitis, while of the rest, more than half (59%) were expatriates of Arab origin (Egyptians, Syrians, Jordanians, Lebanese, and Omani). The study recognized smoking, low BMI, and the male gender to be the most important risk factors for spontaneous pneumothorax in this population. Patients in this study had a lower BMI (19.3) compared to earlier studies in Europeans (37.0). Ayed et al. (2006b) surmised that this could be due to the physiological differences between the two populations. There was a relatively high level of smoking in the population, with an overall prevalence of 34.4% among the men. Over 95% of the patients were men. The occurrence of spontaneous pneumothorax showed a bimodal age distribution, with a peak at <30 years of age, and another one at >40 years. Ayed et al. (2006b) could not find any association of the occurrence of spontaneous pneumothorax with the climatic conditions.

Bitar et al. (2006) studied 24 consecutive patients, all males, diagnosed with PSP in a Kuwaiti hospital to determine the prevalence of Mitral Valve Prolapse (MVP) in this population. All patients and 40 healthy controls underwent chest X-ray and 2D echocardiographic studies. MVP was detected in nine (37.5%) of the PSP patients. Although this percentage is less than that reported previously in other populations, it still is significantly higher than the control group (7.5%). Interestingly, the BMI was lower in patients with PSP compared to the controls. Of the patients, 75% were smokers. However, no association was found between smoking and MVP in the patients.

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