Granulomas are an accumulation of immune cells in the tissue, often the result of an overactive immune response. Granulomas contribute to several inflammatory systemic diseases such as sarcoidosis, berylliosis, and rheumatoid arthritis. For the first time, scientists at CeMM, the Medical University of Vienna and the Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases have thoroughly characterized granulomas in the skin in immense detail. The results provide numerous insights into the composition, structure and signaling pathways of granulomas, providing clues for new therapeutic approaches. The study was published in the journal Immunity.