S1C27P17-3: Cells and elastic fibers are yellow. Collagen bundles are red. Connective tissue mucins are blue. The mucinosis of this lesion of granuloma annulare is easily accepted as an accommodation for increased metabolic needs in a dermal focus. One conceptual approach is to assume that something harmful to normal tissue - something that probably has an affinity for either collagen or elastica - has been deposited in the dermis. In this approach, the lysis of collagen is a characteristic feature of an early lesion of granuloma annulare; a reactive collagenolysis is routinely accompanied by an increased amount of mucinous matrix (one compensates for a loss of the other). The histiocytes, in digesting the connective tissue, may liberate from the connective tissue a foreign component which then would be phagocytyzed; it would be either digested intracellularly, confined in a local granuloma, or transported in the cytoplasm of phagocytes to regional lymph nodes. Palisaded granulomas are metabolically active dumps.

S1C27P17-4: In this lesion of necrobiosis lipoidica diabeticorum, sclerosis of the dermis is a prominent feature; it is most evident to the left and above the center of the field. In this same area, there is a reduction in the amount of elastica (Verhoef van Gieson stain; elastica black and collagen red; elastolysis in zone of sclerosis). As in a lesion of granuloma annulare, it would be a mistake to assume that the area of sclerosis provides clues as to the nature of the initial insult in the dermis. This pattern is representative of a late stage in the evolution of the lesion. The sclerosing process is distinguished by coarse collagen bundles that are compactly aggregated, and by a pattern in which collagen bundles are arranged parallel both to each other and to the surface of the skin. This reorientation of collagen bundles is common to a variety of sclerosing disorders such as morphea (scleroderma) and lupus profundus. A common precursor stage for these disorders is a lymphohistiocytic collagenosis, often with some degree of plasmacytosis in perivascular infiltrates.

S1C27P17-5: In this diagram, normal patterns of  the reticular dermis are represented on the left. To the left, collagen bundles are red, elastic fibers are yellow, interstitial mucinous matrix is blue, and cells (including fibroblasts and factor XIIIa (+) dendritic histiocytes) have brown cytoplasm  and round, black nuclei). Just to the left of the center of the field (near the palisade of cells), activated connective tissue is represented. In this area, there is lysis of collagen bundles (they are smaller in size and fewer in number). The mucinous matrix is expanded (this combination of features might be characterized as the mucinous phase of activation of connective tissue). The palisade of cells represents the boundary for a focal area of activated connective tissue as seen in a  fully developed, but early, palisaded granuloma. In these focal lesions, the lytic changes may be relatively inclusive of all connective tissue fibers. The red zone to the right gives recognition to the sequential changes which are characteristic in the life history of a palisaded granuloma (i.e., mucinous changes commonly give way to fibrosing changes). The streaked, parallel (red) lamellae to the far right depict the late stage in the evolution of such a lesion; the lesion heals in sclerotic patterns in which collagen bundles are coarsened and parallel. Such a lesion may also be elastolytic but, in granuloma annulare, the elastic fibers are relatively resistant; in the reparative phase, they provide a lattice that serves as a template for the reformation of collagen bundles. As a consequence, a healing lesion of granuloma annulare is likely to show preservation of elastica; it generally is characterized by coarsened, but interwoven, (not parallel) collagen bundles. This quality contrasts with the streaked pattern of sclerosis which characterizes lesions of morphea, necrobiosis lipoidica, and lupus profundus.