Hypersensitivity pneumonitis and extrinsic asthma. An unusual association

An unusual but unmissable link between summer-type hypersensitivity pneumonitis and asthma in an old house

While hypersensitivity pneumonitis (HP) and asthma are usually recognized as different disease entities based on their different allergic mechanisms, they may have some connections. A previously healthy 54-year-old Japanese man with no history of allergic diseases was hospitalized due to fever and breathlessness. He had lived in an old musty wooden house. He was diagnosed with acute summer-type HP induced by Trichosporon asahii based on bilateral ground-glass opacities on chest computed tomography (CT), a high titer of serum anti-T. asahii antibody, an increased number of lymphocytes and a decreased CD4/CD8 ratio in bronchoalveolar lavage fluid (BALF) and lung pathology suggestive of HP. However, untypical increased eosinophils in BALF (25.2%) and infiltrative eosinophils around bronchial walls were observed. After systemic corticosteroid treatment was started, he recovered, and was discharged with oral prednisone. However, two weeks after returning to his former house, he had fever and severe cough, and was re-hospitalized. While chest CT showed no abnormal shadows indicating a worsening of HP, pulmonary function test revealed a typical obstructive defect and eosinophilic inflammation in his sputum. He spontaneously recovered after re-hospitalization without increasing any treatments. During this second hospitalization, he was diagnosed with asthma, although it remains to be determined whether both HP and asthma were caused by T. asahii. Clinicians should not miss the possible overlapping presentations between HP and asthma, caused by environmental antigens.

Hypersensitivity pneumonitis: beyond classic occupational disease-changing concepts of diagnosis and management

OBJECTIVE

To review inhaled antigens in home environments that cause hypersensitivity pneumonitis (HP) of varied clinical expressions and histopathologic patterns.

DATA SOURCES

Computer-assisted MEDLINE and manual searches for articles concerning HP, interstitial lung disease (ILD), epidemiology of HP and ILD, challenge procedures of HP, and indoor fungi.

STUDY SELECTION

Published articles concerning inhaled antigens in home environments and HP were selected.

RESULTS

Current criteria for the diagnosis of HP are too restrictive, because most apply only to the classic acute presentation and are of limited value in the subacute and insidious forms. Clinical expressions vary across the gamut of respiratory tract signs and symptoms. Patterns on lung biopsy may include all histopathologic descriptions of idiopathic ILD. The home is the likely causative environment rather than the workplace. Exposures may be occult and require in-depth environmental histories and on-site investigations to detect antigens and sources.

CONCLUSIONS

Natural or environmental challenges have become an important tool for diagnosing HP and determining effectiveness of remediation. Early diagnosis and effective remediation of the cause lead to a high survival rate, whereas diagnosis in advanced stages leads to disability and/or premature death.

Trichosporon asahii-induced asthma in a family with Japanese summer-type hypersensitivity pneumonitis

BACKGROUND

Trichosporon species frequently induce summer-type hypersensitivity pneumonitis (SHP), which is the most prevalent type of hypersensitivity pneumonitis (HP) in Japan, but have not been reported to induce asthma.

OBJECTIVE

Evaluation of a case of asthma induced by Trichosporon asahii.

METHODS AND RESULTS

This report describes a 46-year-old Japanese man who developed asthma induced by T. asahii, following symptoms of HP attributable to the same pathogen, in a case of familial occurrence of SHP. This patient lacked typical findings of HP in his radiograph but had an elevated level of eosinophils in his bronchoalveolar lavage fluid. Open lung biopsy, however, revealed typical pathologic findings of HP when he was free of asthmatic symptoms. His serum was also positive for anti-T asahii antibody, as are the sera of SHP patients. Nevertheless, provocation tests, including returning home and inhalations of T. asahii antigen, reproduced asthmatic features such as airway hyperresponsiveness and reversible bronchoobstruction, but not the features of HP. A skin test with the same antigen also evoked an immediate allergic reaction. An IgE mechanism was suspected but could not be proven by radioallergosorbent test. The patient's son and daughter displayed typical features of SHP, associated with compatible results in their radiographs, bronchoalveolar lavage fluid analysis, serologic and pathologic examinations, and provocation and skin tests.

CONCLUSIONS

To our knowledge, this is the first case of extrinsic asthma, and of coexistent asthma and HP, induced by T. asahii. The patient initially displayed symptoms typical of SHP, which were subsequently replaced by more typical asthmatic symptoms.

Recovery of pulmonary function in farmer's lung. A five-year follow-up study

The recovery of pulmonary function in farmer's lung (FL) was studied during a 5-yr follow-up in 101 patients (20 men and 81 women, mean age 47 yr). At the initial evaluation all patients had the first diagnosed attack of FL. Spirometry, measurement of pulmonary diffusing capacity, and arterial blood gas analysis were done at the time of the diagnosis and 1, 3, 6, 12, and 24 months thereafter. The last follow-up measurements were made 4 to 6 yr after the initial evaluation. Mean FVC improved significantly for up to 1 yr. In mean DLCO there was improvement for up to 2 yr. Mean PaO2 rose to its maximum within 1 month of the initial examination and did not change significantly thereafter. No patient had diagnosed asthma at the time of the diagnosis of FL, but asthma was later diagnosed in 7 patients during the follow-up. In conclusion, the pulmonary function of FL patients improved for up to 2 yr after the initial acute episode. In general, PaO2 improved most rapidly; the improvement in FVC was slower, and the recovery of DLCO took the longest time.

Immunology of hypersensitivity pneumonitis

Hypersensitivity pneumonitis (extrinsic allergic alveolitis) represents a spectrum of granulomatous, interstitial, and alveolar-filling lung disorders of which farmer's lung is a classic example. A major source of offending antigens in these diseases are thermophilic actinomycetes growing in moldy vegetable matter especially Micropolyspora faeni, and members of the Thermoactinomyces genus. Acutely, hypersensitivity pneumonitis presents as cough, dyspnea and fever, with crepitant rales, leucocytosis, diffuse interstitial and alveolar pulmonary infiltrates and a restrictive-type pulmonary functional deficit. Symptoms usually begin 4 to 6 hr after exposure to large quantities of causative organic dust. Chronically, these diseases may present with the gradual onset of cough, dyspnea on exertion, fatigue, anorexia, and weight loss which may progress to pulmonary fibrosis or severe pulmonary insufficiency. While early ideas on the pathogenesis of hypersensitivity pneumonitis support the role of Type III immune complex hypersensitivity, more recent evidence attests to the important and integral role of Type IV or delayed-type hypersensitivity. It is the purpose of this review, therefore, to describe those immune mechanisms relevant to the pathogenesis of hypersensitivity pneumonitis and stress the importance of "local" pulmonary immune responsiveness.