S9C25P16-5: With a colloidal iron stain, the action of enzymatic phenomena has imparted a zonal quality to the field. A central defect is blue and mucinous. In it, a few red collagen bundles and yellow elastic fibers are scattered. The pale yellow area, to the right just below the center of the field, is a cluster of vessels with their common adventitia. At the periphery of the blue pool, the yellow zones are representative of elastic fibers and infiltrates of histiocytes. Infiltrates of histiocytes are particularly prominent near the top of the field. As the lesion has expanded centrifugally, the histiocytes have moved into neighboring dermis and collagen bundles have been entrapped.

S9C25P16-6: Some observers speak of interstitial variants of GA. All examples of GA are interstitial processes. Generally, those who speak of such variants have in mind examples without a central, acellular, well-developed mucinous zone; this field serves as an example of such a pattern. Some of the lesions, of the types which might be characterized as “interstitial” variants, generally are early in their evolution; they show traceries of histiocytes among minimally altered collagen bundles. In such lesions, mucinous changes are minor. Other “interstitial” variants are of the type pictured in this field; they are late, resolving lesion in which collagen bundles have been partially restored. Such late lesions represent the desmoplastic phase in the life history of a lesion of GA. In this example, there appears to be a focus with early changes near the bottom of the field; in the latter site, the interstitial cells probably are activated histiocytes. Near the top of the field, sclerosis is more pronounced; collagen bundles are coarsened and more brightly acidophilic; here, the interstitial cells probably are mostly fibroblasts.

S9C25P16-7: In this lesion of actinic granuloma (Verhoeff-van Giesen stain), elastotic material forms a prominent band in the upper 1/2 of the dermis on the left; this is an intact zone of solar elastosis. We might propose a temporal vector directed from left to right with the more advanced, or older portion of an elastolytic process on the right of the center of the field. There is a band of fiber-free dermis bounded superiorly by the papillary dermis (a zone normally unaffected by solar elastosis) and inferiorly by the zone of elastotic material that extends into the reticular dermis for a variable depth (focally extending to below the level of a hair follicle). A few islands of elastotic material have survived in the fibrolytic zone. This relatively anelastic zone is the trail of an elastolytic process which spreads centrifugally into the actinically damaged dermis. The process is elastolytic and the mediating cells are epithelioid histiocytes in granulomatous patterns (the lesion qualifies as a granulomatous elastolysis; if peculiar to actinically damaged skin, the process is actinic granulomatous elastolysis). See S9C22VA2-2 for a drawing in which the relationships between epithelioid histiocytes and elastic fibers are depicted. Other forms of granulomatous elastolysis include granulomatous lax skin, as well as granuloma annulare and necrobiosis lipoidica.

S9C25P16-8: The trail of anelastic dermis is represented on the right. Near the center of the field, the extremity of the anelastic zone abuts upon the zone of solar elastosis. Epithelioid histiocytes and giant cells are represented at the interface between the elastotic zone and the anelastic zone.

S9C25P16-9: At the extremity of the zone of granulomatous elastolysis in a lesion of actinic granuloma, the granuloma is interstitial (connective tissue fibers of the reticular dermis are irregularly preserved among the epithelioid histiocytes). On the right side of the field, elastic fibers are not represented; they have been phagocytyzed and digested. A few small, pale fibers are in the cytoplasm of a giant histiocyte to the right of the center of the field (green arrow). To the left of the center of the field, a second green arrow identifies elastic fibers that are better preserved in the cytoplasm of a histiocytic cell. Elastic fibers are more regularly spaced to the far left of the field. The lesion is less organized than a lesion of granuloma annulare; the patterns resemble a foreign-body reaction.