Granulomatous infiltrates are characterized by the presence of mononuclear or multinuclear phagocytes, deriving from monocytes. They are spread between collagen bundles or accumulate in nodular granulomas, without (sarcoidosis) or with (lupus vulgaris) caseation. Their localization in the dermis is responsible for a brownish-yellowish colour, which best is seen under pressor through a glass spatula (diaphanoscopy).