ORIGINAL ARTICLE
Causes and Presenting Features in 85 Consecutive Patients With Hypersensitivity Pneumonitis

https://doi.org/10.4065/82.7.812Get rights and content

OBJECTIVE

To assess the current spectrum of causes and clinical features associated with hypersensitivity pneumonitis (HP).

PATIENTS AND METHODS

We studied consecutive patients with HP diagnosed at the Mayo Clinic in Rochester, Minn, from January 1, 1997, through December 31, 2002. Diagnostic criteria for HP included the following: (1) presence of respiratory symptoms, (2) radiologic evidence of diffuse lung disease, (3) known exposure or a positive serologic test result to an inciting antigen, and (4) no other identifiable cause for the lung disease. If there was no identifiable inciting antigen, 1 of the following 2 criteria was required: (1) lung biopsy specimen that demonstrated features of HP or (2) bronchoalveolar lavage lymphocytosis and high-resolution computed tomographic evidence of ground-glass opacities or centrilobular nodules bilaterally.

RESULTS

The mean ± SD age of the 85 study patients was 53±14 years; 53 patients (62%) were women. Only 2 patients (2%) were current smokers. Chronic (≥4 months) respiratory symptoms were present in 66 patients (78%). Histopathologic confirmation was obtained in 64 patients (75%). The cause was identified in 64 patients (75%), and the most common causes were avian antigens (34%) and Mycobacterium avium complex in hot tub water (21%). Farmer's lung disease accounted for 11% of cases, and an additional 9% were related to household mold exposure. The inciting antigen was not identifiable in 25% of patients.

CONCLUSION

Most patients with HP seen at this tertiary care referral center in the Midwest region of the United States had chronic HP, and the most common causes were exposure to birds and exposure to hot tubs.

Section snippets

PATIENTS AND METHODS

We conducted a computer-assisted search of the Mayo Clinic, Rochester, Minn, database to identify patients evaluated for HP at our medical center during a 6-year period from January 1, 1997, through December 31, 2002. Diagnostic criteria for HP included the following: (1) presence of episodic or persistent respiratory symptoms, (2) radiologic evidence of diffuse lung disease, (3) known exposure or a positive serum precipitin test result to an inciting antigen, and (4) no other identifiable

RESULTS

Demographic data and presenting clinical features of 85 consecutive patients with HP are summarized in Table 1. The mean ± SD age of the patients was 53±14 years (range, 13-90 years); 53 (62%) were women, and 32 (38%) were male. Only 2 patients (2%) were current smokers. Before the evaluation at our medical center, 23 patients (27%) had been diagnosed as having HP.

The most common presenting symptoms were dyspnea (93%) and cough (65%). Respiratory symptoms had been present for 4 months or more

DISCUSSION

Avian antigens (34%) and M avium complex associated with hot tub water (21%) were the most common causes of HP in this study cohort. Although controversy continues regarding the underlying pathophysiology of hot tub lung disease, the weight of evidence suggests HP rather than infection as the cause.8, 9 A wide array of potential antigens can cause HP, but it is noteworthy that farm-related antigens, house molds, avian antigens, and exposure to hot tub-related M avium complex accounted for all

CONCLUSION

Most patients with HP seen at this large tertiary care center in the Midwest region of the United States had chronic HP, and the most common causes included avian antigens and hot tub-related M avium complex. In 25% of patients, the presumptive antigen could not be identified. Additional research is needed to develop methods for identifying of-fending antigens, to formulate diagnostic criteria, and to define the natural history of and prognostic factors for HP.

REFERENCES (18)

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  • Utility of serum immunoglobulin A antibody against glycopeptidolipid core antigen in the diagnosis and management of hypersensitivity pneumonitis associated with Mycobacterium avium complex: A case report

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    Inhalation of aerosolized Mycobacterium avium complex (MAC) from water sources can cause HP, more commonly known as “hot-tub lung” based on its typical source [4]. Although the causative antigens of HP vary by geographic region, a previous report in the USA showed that MAC was the second most common cause of HP after avian antigens, accounting for 28% of patients with the identified antigen [5]. Nevertheless, few studies have examined the efficacy of serum antigen-specific antibody testing in HP associated with MAC.

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