Non-specific interstitial pneumonia J84.9

First described by Katzenstein in 1994

According to the classification of the ATS (American Thoracic Society) and the ERS (European Respiratory Society) one of the representatives of the main forms of idiopathic "interstitial pneumonia" (MajorIIPs). See also Interstitial pneumonia.

Non-specific interstitial pneumonia (NSIP) is a subgroup of interstitial pneumonia.

It is divided into 2 subgroups:

• cellular (c)NSIP: interstitial cell-rich inflammation with a pronounced alveolitis and distinct milky glass opacities in CT
• fibrotic (f)NSIP: here fibrosis predominates, which is similar to IPF

Unknown

The NSIP accounts for approximately 25 % of all IIPs. Compared to other interstitial pneumonia, it mainly affects younger patients (40-50 years) and prefers women who have never smoked.

The etiopathogenesis is not clear. However, the disease often occurs in combination with other underlying diseases such as collagenosis, exogenous allergic pneumonitis and drug-induced lung damage. Often there is an association with febrile disease ("haven't recovered from the last infection.")

The NSIP is mostly subacute:

• dry cough
• Exercise dyspnea
• Tiredness
• Weight loss (up to 50 %)
• subfebrile temperatures
• Watch glass nails and drum flail fingers are rare

In HRCT, milky glass-like turbidity is often found, predominantly symmetrical and subpleural, but also peripheral and basal. There are consolidations, but no nodular drawing. Often associated with a volume reduction of the lower lobes.

LDL slightly increased, BSG accelerated, occasionally antinuclear AK(ANA) or rheumatoid factors slightly increased or increased in the context of the additional underlying diseases.

Any type of tissue removal - sometimes even the BAL - can trigger an acute flare of disease in IPF/UIP. This is not described for the other subgroups. Therefore, the indication for biopsy should be narrowly defined.

In bronchial lavage, NSIP shows an increased total cell count and an increased number of eosinophils, as well as an abundance of neutrophils and lymphocytes. Alveolar macrophages are usually not detectable. Under no circumstances are fibroblast cell nests found in NSIP.

It is not uncommon to find changes in different biopsies that correspond to a UIP. It is therefore still unclear to what extent these are actually entities. It is also being discussed whether NSIP can change into an IPF/UIP.

HRCT is the gold standard today. The indication for taking a biopsy or a BAL must be narrowly defined, especially if there are no therapeutic consequences (see also histology).

• Other forms of interstitial pneumonia(IPF/UIP; COP; AIP; RB-ILD; DIP; LIP;)
• Collagenoses
• Asbestosis
• exogenous allergic alveolitis
• Sarcoidosis

• respiratory insufficiency
• pulmonary hypertension
• cor pulmonale
• lung carcinoma

Patients with NSIP should always be treated, as the disease responds well to drug treatment. Occasionally there are descriptions of courses in which the patients remained stable for years under treatment. Even complete remissions are possible under the therapy.

If fibrotic changes dominate, the therapeutic effect is similar to that of IPF (drug treatment has only a limited effect; early listing for transplantation is required).

Therapeutic procedure for NSIP:

Initially, monotherapy with prednisone should be given. Only if the effect is insufficient or in the further course to reduce the toxicity of the cortisone is azathioprine added.

Prednisolone: Initial dose 1 mg/kg bw/d, but not more than 50 mg/d. After 4 weeks the dose is halved, after another 4 weeks it is halved again.

Azathioprine: 2 mg/kg bw/d, but not more than 150 mg/d. The dose should be increased in 50 mg steps weekly until the target dose is reached.

In case of intolerable side effects of corticosteroids or in elderly patients, prednisolone can be combined with 3 x 600 mg ACC or used as sole therapy - following the IFIGENIA study. The course of the disease does not seem to be negatively affected by this (the chronic inflammation underlying fibrosis probably reacts positively to the reduction of antioxidants).

The forecast is determined by the subtype: (c)NSIP has the better forecast. Total lethality about 11%, mean survival time: 17 years. Complete remissions are possible.

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