Unexpected Granulomatous Infiltration

Granulomatous dermatitis can be categorized into sarcoidal, tuberculoid, suppurative, palisading, and interstitial patterns. The characteristic pattern can usually lead to specific diagnosis, such as sarcoidosis, tuberculosis, deep fungal infection, necrobiosis lipoidica, and granuloma annulare. However, some granulomas did not show specific arrangement, or they show distinct arrangement but cannot be categorized into those patterns. In this lecture, we will demonstrate several uncommon cases presenting unexpected granuloma formation in either inflammatory skin disease, infection, or neoplastic disease and show the ways or pitfalls to make the correct diagnosis.