Comparative ultrastructural study of generalized and localized granuloma annulare.

The dermal changes in four cases of generalized granuloma annulare (GGA) and in four of localized granuloma annulare (LGA) were studied ultrastructurally, and the findings in the two groups were compared. The basic alterations were similar in both types, and showed varied stages of development. The cellular infiltrate was composed mostly of histiocytes. Cell debris was found in all lesions. The degenerative changes affected the collagen fibers, the elastic fibers, and the cellular infiltrate. Of special interest are the following findings in GGA: First, masses of intercellular fibrin material were seen only in the lesions of GGA. Second, thick and multilayered basal lamina around capillaries was apparently more common in the generalized form. These changes may suggest that a more pronounced immune reaction is responsible for the development of the generalized form of the disease.