Some diseases can be thought of as "cousins"; they are related but different in at least a few distinct ways. Learning these diseases together can be useful because examining there similarities and differences side by side helps put each disease into a conceptual context in your mind.
Still’s disease and Erythema Marginatum
• | both reticular/annular erythema |
• | both histologically similar: superficial perivascular infiltrate of neutrophils, and dust, but no fibrin or RBC’s (i.e. no LCV) |
• | both immune complex diseases (both with symptoms of arthritis) |
• | memory tool: both associated with disease activity – Still’s appears in the evening with the high fevers; e. marginatum is associated with active carditis |
Erythema Marginatum:
• | associated with active carditis |
• | one of 5 major Jones criteria for Rheumatic Fever: subcutaneous nodules, Sydenhams chorea, carditis, polyarthritis |
Still’s disease:
• | rash appears in evening with high temperature |
• | dermal edema with dilated vessels |
Cylindroma and Eccrine Spiradenoma
• | both composed of lobules surrounded by hyaline sheath (though more striking in cylindroma) |
• | both composed of two types of tumor cells |
• | small basophilic cells – arranged along periphery of the tumor lobules |
• | larger, paler cells – in the center of the islands |
• | both belong to the least mature group of appendage tumors |
• | eccrine spiradenoma – direction of differentiation is toward both ductal and secretory segments of eccrine sweat glands |
• | cylindroma – a very immature sweat gland epithelioma, partially eccrine and partially apocrine in differentiation |
cylindroma:
eccrine spiradenoma:
• | no characteristic distribution |
Epidermolysis Bullosa Acquisita and Bullous SLE
• | has the following in common with EBA: |
• | antibodies recognize EBA antigen (type VII collagen) |
• | the split occurs in the sublamina densa zone |
• | indirect immunofluorescence may be positive in intact or separated skin |
• | presence of HLA-DR2 is markedly increased in both conditions |
• | bullous LE distinctive features include: |
• | a diagnosis of SLE by criteria of the ARA |
• | a widespread, non-scarring vesicobullous eruption |
• | (skin fragility, scarring, and milia are not features) |
• | often begins in second or third decade (EBA in fourth or fifth) |
• | histology characteristically like that of dermatitis herpetiformis (rare in EBA) |
• | remitting and often resolves in less than a year (EBA often lasts many years) |
• | most patients respond dramatically to dapsone (EBA patients do not predictably respond to any treatment) |
Eruptive vellus hair cysts vs. Steatocystoma multiplex
• | both can be autosomal dominant |
• | steatocystoma cysts may contain one or more lanugo hairs |
• | hybrid cysts with features of both are sometimes seen |
Generalized Eruptive Histiocytoma
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Xanthoma Disseminatum
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Eruptive Xanthomas
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• | non-lipidized histiocytes |
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* xanthoma cells = lipidized histiocytes
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