Primary Spontaneous Pneumothorax Detected During a Medical Checkup

Abstract

To the Editor: Primary spontaneous pneumothorax (PSP) is a common clinical problem that occurs in apparently healthy subjects. The incidence of PSP was reported to be 7.4 men per 100,000 population per year and 1.2 women per 100,000 population per year.1Melton LJ Hepper NGG Offord KP Incidence of spontaneous pneumothorax in Olmsted County, Minnesota: 1950 to 1974.Am Rev Respir Dis. 1979; 120: 1379-1382PubMed Google Scholar A small percentage of patients is considered to be asymptomatic,2Peters JI Sako EY Pneumothorax.in: Fishman AP Elias JA Fishman JA Fishman's pulmonary diseases and disorders. 3rd ed. McGraw-Hill, New York, NY1998: 1439-1451Google Scholar but no detailed study has yet been reported. We report here the incidence of asymptomatic PSP among young adults in Japan, detected during medical checkups for university students. Medical checkups for students are provided every year at Hiroshima University, and 8,850 students visited the Health Service Center between April and May 1998. Three cases of PSP were detected by examining indirect chest radiographs (width, 100 × 100 mm) of 8,841 students (men, 5,357; women, 3,484). The three students with PSP were men with the following characteristics: age, 18, 19, and 20 years (mean and median among the total male students examined were 21.4 and 21.0 years, respectively [n = 5,357]); height, 1.80, 1.72, and 1.70 m (mean, 1.72 m; median, 1.72 m [n = 4,924]); and body mass index (BMI), 22.4, 17.3, and 17.3 (mean, 21.5; median, 21.1[n = 4,924]), respectively. Two of the students had never smoked. The detailed history, obtained after diagnosis, revealed that two of the subjects had noticed chest pain around the time of their checkup. These two subjects showed spontaneous improvement on chest radiographs taken 2 to 3 weeks after diagnosis, while the remaining subject with massive pneumothorax (Fig 1) was admitted to a hospital for aspiration treatment. Only two cases of PSP had been detected among a total of 69,542 students during checkups at our center between 1989 and 1997. We cannot explain the high incidence found in 1998, but these cases may support the hypothesis of PSP clustering reported by Smit et al.3Smit HJM Devillé WL Schramel FMNH et al.Spontaneous pneumothorax: predictable mini-epidemics [letter]?.Lancet. 1997; 350: 1450Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Our findings suggest that the percentage of asymptomatic PSP is not negligible and that some cases may require medical intervention. PSP should be considered in the differential diagnosis of young men with a greater-than-average height or low BMI who complain of generalized malaise.