[Ultrastructural study of a case of Miescher-Leder granulomatosis disciformis chronica et progressiva].

Ultrastructural study of a case of granulomatosis disciformis occurring on the legs of a 62-year-old woman. The diagnosis is based upon the contrast between the clinical aspect of necrobiosis lipoidica and the histologic aspect of inflammatory granulomatous infiltrate of dermis without necrobiosis nor palisading. Electron microscopic findings are: perivascular mixed cell infiltrate and histiocytic granuloma with lysosomial and phagocytic activity; degenerative and necrotic cellular alterations; modifications of collagen fibres with two types of fibres: the thinnest are the most numerous and have a mean diameter of 50 nm, the thickest of 110 nm; no significant lesions of capillary walls. These findings suggest the following succession of pathological events: cellular necrosis, lysosomial and phagocytic activity, scarring. Some descriptions of necrobiosis lipoidica and granuloma annulare seem to be quite similar and our findings are in favour of the unity of these three illnesses.