This 63-year-old man with diabetes mellitus, hypertension, cardiovascular disease, and arthritis developed a pruritic scaly eruption on the extensor surfaces of his arms and neck following a trip to New Orleans where he spent time in the sun. Lesions were confined to sun exposed sites and clearly worsened after sun exposure. A skin biopsy showed the typical changes of annular elastotic granuloma, and many of the lesions were treated successfully with intralesional steroids. Annular elastolytic giant cell granuloma (AEGCG) and actinic granuloma (AG) are terms for a clinicopathologic entity whose place in the dermatologic lexicon is still debated. Clinically, these disorders typically present as either single or multiple asymptomatic thin yellowish plaques on the forehead or trunk (AEGCG), or as papules and plaques that slowly enlarge and coaelesce primarily on sun-exposed skin (AG); these latter plaques develop a raised border and slight central atrophy with hypo- or depigmentation. A few lesions may appear on non-sun-exposed skin or extend from adjacent areas. Older adults (>50 y.o.), and men more often than women, are usually affected. Occasionally there is associated intense pruritis.
The lesions clinically resemble necrobiosis lipoidica (on the face) or more commonly granuloma annulare, and this distinction cannot be made on clinical grounds. It has been argued, therefore, that AEGCG/AG is merely granuloma annulare that happens to occur on sun-exposed skin. Histologically, though again still debated, the data seem to favor a distinction between these entities. AEGCG/AG typically shows numerous multinucleated giant cells forming interstitial or sarcoidal granulomas, macrophages containing damaged elastic fibers (elastophagocytosis), and scant mucin deposition. Granuloma annulare has few multinucleated giant cells, granulomas with a palisaded appearance, and deposition of mucin. A recent report also found no evidence of elastophagocytosis in granuloma annulare even in lesions on sun-exposed skin. It also appears that diabetes, which can be seen in generalized granuloma annulare, is not linked to AEGCG/AG, while there are many reports of temporal arteritis occurring in patiens with AEGCG/AG. One pathologic mechanism proposed for both AEGCG/AG and temporal arteritis is cell-mediated autoimmunity directed against altered elastic fibers, as a result of actinic damage.
Unlike granuloma annulare, AEGCG/AG is often difficult to manage and resistant to treatment. Published reports on treatment for AEGCG/AG mainly consist of case reports and other anecdotal evidence. Intermittent intralesional corticosteroids have worked temporarily in our patient, but his lesions continue to occur and avoidance of steroids would be prudent given his diabetes. Cyclosporin A, isotretinoin and acitretin have all been reported to work in single case reports.
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Histologic sections of skin show an unremarkable epidermis. In the superficial dermis there is a prominent granulomatous infiltrate consisting of histiocytes and giant cells. Throughout the lesion, there is a loss and disruption of collagen fibers and focal elastophagocytosis. There is a moderate lymphocytic infiltrate within the granulomatous zone. A Verhoeff-van Giesen stain highlights the loss and disruption of elastic fibers. Additionally, an Alcian Blue stain for mucin is negative.