Discoid versus Subacute Lupus erythematosus

Histological Differences Summary

• Inflammatory Infiltrate: DLE generally exhibits a dense, deep perivascular and periadnexal infiltrate. SCLE often shows a sparse, superficial perivascular infiltrate.
• Epidermal Changes: DLE is marked by prominent hyperkeratosis, thickened basement membrane, and follicular plugging. SCLE tends to have more pronounced epidermal atrophy.
• Dermal Changes: DLE often shows significant Basement Membrane Zone (BMZ) thickening and sometimes subepidermal edema.
• Pilosebaceous Atrophy: This is often a key differentiator, with DLE showing more significant scarring and destruction of follicles.
• Direct Immunofluorescence (DIF): DLE shows granular deposits of IgM, IgG, or IgA along the DEJ (the lupus band test). SCLE may also show this, but studies suggest SCLE may have particulate staining of IgG or IgM through the lower epidermis rather than just at the junction. 

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• Dermatoscopic Comparison

• Follicular Features: DLE commonly presents with prominent follicular plugs and white follicular halos (perifollicular white halos), which are less prevalent in SCLE.
• Vascular Patterns: Both show polymorphic vessels on a red background. DLE often shows linear vessels, while SCLE often displays a combination of linear and dotted vessels.

• Key Differences Summary

• DLE: Shows thick white scales, prominent follicular plugging, and white scarring areas.
• SCLE: Shows fine scales, more surface pigmentation (grey-brown dots), and less scarring. 

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• Scales & Color: DLE features thick, adherent white scales (carpet tack sign), while SCLE typically has fine white scaling.
• Scarring Signs: DLE is marked by white, structureless areas (representing scar tissue), whereas SCLE is often non-scarring and rarely presents with intense follicular destruction.
• Pigmentation: DLE more commonly presents with prominent peripheral pigmentation, while gray-brown dots are often noted in SCLE. 

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