Erythema Elevatum Diutinum

Erythema elevatum diutinum, like granuloma faciale, is anatomically fixed and chronic (S8C19P6-1); it smolders. Acute episodes are superimposed on lesions that are chronically inflamed. It is a necrotizing vasculitis; in the acute phase, the vessels are fairly uniformly involved (S8C19P6-2-4). The affected vessels show a smudgy, fibrinoid necrosis of their walls. In areas, the fibrin is arranged in lamellar patterns; during repair the fibrin is converted to laminated hyalin (toxic hyalin). The perivascular spaces contain infiltrates of lymphoid cells and neutrophils. In an acute phase, some of the inflammatory cells show fragmentation of their nuclei.

Patterns of both repair and ongoing damage - changes that come be associated with the patterns of an active vasculitis - may coexist in a single lesion. Repair is manifested by the formation of a fibrous matrix (a matrix different from the normal fibrous matrix of the reticular dermis) (S8C19P6-6-8, & S8C19cP6c-3-5)  and by patterns of reactive angioplasia. New vessels proliferate in the area of the original necrotizing angiitis (S8C19P6-5-8). The new vessels are thin with narrow lumens and swollen endothelium. The new vessels also are susceptible to the factors promoting inflammation. The inflammatory process of the original vascultitis likely will involve the newly formed vessels. Focally, with progression of the vasculitis, patterns of fibrinoid necrosis and leukocytoclastic angiitis again will be a feature (S8C19bP6b-4 & 5, & S8C19cP6c-1-2). From these damaged vessels, and into the newly formed, laminated fibrous matrix, red blood cells extravasate. The extravasated red blood cells eventually breakdown, releasing lipids into the tissue. Histiocytes are attracted to these areas; they function as phagocytes and lipids are deposited in their cytoplasm. Some of the histiocytes contain hemosiderin. In this smoldering phase of the inflammatory process, the lesion takes on xanthomatous qualities (extra-cellular cholesterolosis).

Erythema elevatum diutinum (EED) is an ill-defined disorder. In the fibrous stage, the patterns become less specific.It is likely that a variety of lesions have been included in the category. In S8C19aP6a-1-4, some of the patterns are acceptable in the category of EED, but the lesions have an ill-defined lobular quality (S8C19aP6a-1) and the endothelial cells are somewhat epithelioid (S8C19aP6a-4). On the other hand, patterns of toxic hyalin are represented, and there are features of leukocytoclastic angiitis (S8C19aP6a-4).

Degos Disease

Degos  disease (S8C20P7-1) is usually a multi-system disease, mediated at the level of a vascular plexus. Rare cases of Degos disease, limited to the skin, have been reported. Degos  disease is a thrombotic angiitis with an accompanying venulitis or phlebitis. In the skin, the small vessels of the reticular dermis are affected (S8C20P7-2-4). In other organ systems, muscular arteries and the accompanying veins are affected (S8C20P7-5-7). The occlusion of arterial, or arteriolar vessels seems to be a slowly obliterative process; the indolence of the process allows for some degree of repair to develop as a compensation for the loss of blood supply. A wedge of coagulated, necrotic tissue usually is not produced in the area of the compromised blood supply. Instead, the specialized tissues undergo a form of atrophy. In the skin, the atrophic dermis is thin; it has a mucinous quality, The atrophic epidermis is reduced to 2 or 3 cell layers. The epidermis shows vacuolar changes at the dermal-epidermal interface. In the dermis, collagen bundles are reduced in size and widely spaced in a mucinous matrix. The dermal vessels are surrounded by lymphoid infiltrates.

In a fully developed lesion of the skin, the arteriole shows fibrous obliteration of its lumen. In the gut, the affected muscular artery in the serosa shows fibrous obliteration of its lumen with partial preservation of the internal elastic lamina (angiitis obliterans). The wall of the vessel may contain focal infiltrates of lymphoid cells. In the gut, the neighboring vein may show a mural thrombus (S8C20P7-5-7).

The mucosa of the gut, in the affected sites, shows ulceration and organizing granulation tissue. A perforation may develop in the site of one of the G-I lesions.

Lymphocytic Vasculitis

For some observers, the designation, vasculitis, only has relevance to vascular disorders in which neutrophilic infiltrates, showing leukocytoclasia (S8C22P9-1 & 2), are associated with necrosis of the “walls” of the affected vessels. In practice, the same observers are more lenient in their interpretations; interstitial infiltrates of neutrophils with leukocytoclasia usually will prove to be sufficient in establishing a diagnosis of leukocytoclastic angiitis, if the clinical impression is leukocytoclastic vasculitis. Necrosis of the wall of the adjacent vessels will not be a requisite.

The category of lymphocytic vasculitis has utility (S8C34bVA7b-1-4). At the level of conceptual discussions, some examples of perivenular lymphocytic infiltrates, even in the absence of necrosis of the walls of the affected vessels, are best characterized as lymphocytic vasculitis. Some vasculitic disorders, showing fibrinoid necrosis of the walls of vessels, are never characterized by a significant component of neutrophils in the perivascular infiltrates; rickettsial infections provide an example; some lesions of pityriasis lichenoides et varioliformis acuta   similarly qualify as lymphocytic vasculitis. Some lesions, with pure perivascular lymphoid infiltrates, are common in the setting of a “drug eruption ” and are associated with perivascular collections of extravasated red blood cells. Lymphocytic vasculitis is the most appropriate designation for such lesions (S8C21P8-1-3, & S8C22P9-3-5). On the lower extremities, certain perivascular infiltrates extend along vessels into the papillary dermis. They are associated with extravasated red blood cells and often with hemosiderin deposits.Such lesions are sometimes classified as capillaritis; they are encountered in the setting of the pigmented purpuras. Lesions in the latter category commonly are associated with mild lichenoid patterns at the dermal-epidermal interface; they qualify as superficial lichenoid lymphocytic vasculitides (S8C21P8-4). Clinically, they fall in the category of the pigmented purpuras (S8C24VA6-5).

Wegener’s Granulomatosis

Wegener’s granulomatosis was defined as a disorder of the respiratory tract, involving both lungs and the upper respiratory tract. It may, however, be a multi-system disorder and, as such, may involve the skin and the kidneys. In the lung, the lesions are both vasculitic and granulomatous; the infiltrates may be characterized by neutrophilic infiltrates and zones of necrosis.The lesions may be complicated by reparative changes with broad zones of inflamed, organizing fibrous tissue (S8C23P10-1-3). Granulomas may be extra-vascular, but granulomatous angiitis also may be a feature (S8C23P10-4).

In the skin, the lesions tend to be vasculitic; they may show fibrinoid necrosis and neutrophilic infiltrates with leukocytoclasia. Often, the latter features are associated with components which clearly are granulomatous, either directly involving the walls of vessels, or in the patterns of extra-vascular granulomas (S8C23P10-5 & 6).