Nonspecific interstitial pneumonia is an idiopathic interstitial pneumonia that occurs mainly in women 40 to 50 years of age. Patients have cough and dyspnea, which may be present for months to years. Diagnosis is with high-resolution CT and lung biopsy. Treatment is with corticosteroids and sometimes other immunosuppressive drugs.
Nonspecific interstitial pneumonia (NSIP) is an idiopathic interstitial pneumonia. It is much less common than idiopathic pulmonary fibrosis (IPF). Most patients are women, are between the ages of 40 and 50 years, and have no known cause or association. However, a similar pathologic process can occur in patients with a systemic rheumatic disorder (in particular, systemic sclerosis or autoimmune myositis), in some forms of drug-induced pulmonary disease, and in patients with hypersensitivity pneumonitis.
Clinical presentation of NSIP is similar to that of IPF. Cough and dyspnea are present for months to years.
Constitutional symptoms are unusual, although a low-grade fever and malaise are possible.
Diagnosis of Nonspecific Interstitial Pneumonia
High-resolution CT (HRCT)
Surgical lung biopsy
The diagnosis of nonspecific interstitial pneumonia should be considered in patients with unexplained subacute or chronic cough and dyspnea. Diagnosis requires HRCT and always requires confirmation by lung biopsy. NSIP is a diagnosis of exclusion that requires careful clinical review for possible alternative disorders, in particular systemic rheumatic disorders, hypersensitivity pneumonitis, and drug toxicity.
Chest x-ray primarily shows lower-zone reticular opacities. Bilateral patchy opacities are also possible.
HRCT findings include bilateral patchy ground-glass attenuation, irregular lines, and bronchial dilation (traction bronchiectasis), generally with a lower lung zone distribution. Subpleural sparing is possible. Honeycombing is rare.
Image courtesy of Harold R. Collard, MD.
Bronchoalveolar lavage fluid has an increased percentage of lymphocytes in more than half of patients, but this finding is nonspecific.
Surgical lung biopsy is required for a diagnosis of NSIP. Histologically, most patients have some degree of fibrosis. The main feature of NSIP is temporally homogenous inflammation and fibrosis, as opposed to the heterogeneity in usual interstitial pneumonia. Although the changes are temporally uniform, the process may be patchy, with intervening areas of unaffected lung.
Treatment of Nonspecific Interstitial Pneumonia
Corticosteroids with or without other immunosuppressive drugs
Prognosis seems to depend most on the degree of fibrosis found during surgical lung biopsy. Almost all patients with primarily cellular disease survive at least 10 years. However, with increasing fibrosis, survival worsens.
Key Points
Nonspecific interstitial pneumonia is uncommon; most patients are women, are between the ages of 40 and 50, and have no known risk.
Exclude systemic rheumatic disorders (particularly systemic sclerosis and autoimmune myositis), drug-induced lung injury, and hypersensitivity pneumonitis and do surgical lung biopsy.
Prognosis is worse if biopsy shows more fibrosis.
