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| • | red (erythema), raised (elevatum), with a strong tendency toward persistence (diutinum) rather than toward involution |
| • | rare; distributed acrally and symmetrically over extensor surfaces (trunk generally spared) |
| • | pathogenesis: most likely caused by immune complex deposition (Arthus reaction) |
| • | associated IgA monoclonal gammopathy ? |
| • | treatment: dramatic response to dapsone or sulfapyridine (sulfones are suppressive not curative and exacerbations are more severe with each subsequent withdrawal of meds) |
ddx:
| • | Sweet’s syndrome: distinguished by character and distribution of lesions, and no LCV on histology |
| • | granuloma faciale: (a histologic not clinical ddx) less vascular involvement, more eosinophils and strict regular sparing of the overlying epidermis |
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