[The updated S2k guideline for the diagnosis of idiopathic pulmonary fibrosis : Essential aspects for pathology].

Idiopathic pulmonary fibrosis (IPF) is a specific form of chronic progressive fibrosing nonreversible interstitial lung disease of largely unknown origin. In high-resolution computer tomography (HRCT) and histopathology it presents with a UIP pattern. To diagnose IPF, (i) an ILD of known origin must be excluded (e.g., hypersensitivity pneumonitis, lung involvement in autoimmune or other systemic disease, and drug-induced ILD) and either (ii) the presence of a UIP pattern in HRCT or (iii) specific combinations of HRCT and histopathology is necessary. The diagnosis of IPF requires interdisciplinary collaboration and a structured procedure. The updated S2k guideline focuses on the IPF diagnostic process and describes the criteria of a UIP pattern in HRCT and histopathology that are differentiated into the categories "UIP pattern," "probable UIP pattern," "indetermined for UIP," and "alternative pattern." Depending on the anamnestic, clinical and serologic findings, HRCT, and - if acquired - histomorphology features, an algorithm to diagnose the IPF is recommended. If a UIP pattern in HRCT is present, IPF can still be diagnosed without further bioptic examination. Additionally, recommendations for the use of surgical lung biopsy (SLB), transbronchial lung biopsy, and the relatively new transbronchial lung cryobiopsy (TBLC) procedure are provided. In contrast to the international guideline, the S2k guideline group evaluated TBLC based on recent studies to be advantageous compared to the SLB, as the diagnostic value and the side-effect rate was assessed to be acceptable and more patients with progressed ILD can be biopsied by TBLC. It is therefore expected that by using TBLC the rate of unclassifiable ILDs can be reduced.