| • | Lichen Planus (and variants) |
| • | Collagen Vascular Disease |
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These diseases also share a common "lichenoid" histology with pigmentary incontinence that creates a characteristic clinical "post-lichenoid" pigmentation.
| • | Lichen Planus (and certain variants) |
| • | lichen simplex chronicus (which can also be somewhat violaceous in black skin) |
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The first list is more useful for differential diagnosis because you may be presented with a rash that is poorly characterized but clearly violaceous in quality and it is useful to think of this list (e.g. photolichenoid drug vs. actinic LP vs. collagen vascular disease) OR you may see post-lichenoid pigment and again the list is useful (especially when you add erythema dyschromicum perstans).
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