Gold Standard Test for Discoid Lupus Erythematosus (DLE)
Skin biopsy for histological analysis is the gold standard diagnostic test for DLE. 1, 2, 3, 4
Diagnostic Approach
The diagnosis requires both clinical assessment and histopathological confirmation through skin biopsy. 1, 2, 3 While clinical features may suggest DLE, many conditions can mimic lupus erythematosus, making histological examination mandatory for definitive diagnosis. 1, 4
Biopsy Technique and Specimen Requirements
- Perform either complete excision of small lesions or an incisional biopsy (spindle-shaped or punch biopsy of at least 4 mm) to ensure adequate tissue for histopathological workup. 1
- Select the biopsy site from an active lesion showing characteristic features such as well-demarcated discoid erythematous plaques with adherent scales, follicular plugging, and central atrophy. 4, 5
Pathognomonic Histological Features
The histological diagnosis of DLE requires identification of the following characteristic features: 4, 5
- Hyperkeratosis with follicular plugging
- Focal epidermal thinning with vacuolar alteration of the dermo-epidermal interface
- Thickening of the epidermal basement membrane
- Superficial and deep perivascular and periadnexal lymphocytic infiltrate
- Interstitial mucin deposition
- Interface dermatitis 5, 6
Adjunctive Immunopathological Testing
Direct immunofluorescence (DIF) should be performed when the diagnosis is uncertain or serology is negative, as it may reveal deposits of immunoglobulins (particularly IgM and IgG) and complement at the dermo-epidermal junction. 4, 5 This test was performed in 33 cases where diagnosis was in doubt clinically or serology was negative. 5
When to Perform Repeat Biopsy
A follow-up repeat biopsy is recommended if there is a change in the clinical morphology of the lesions or if there is a lack of response to treatment. 1, 7, 2 This ensures that evolving disease or alternative diagnoses are not missed.
Complementary Diagnostic Tools (Not Gold Standard)
While not gold standard, these tools can support diagnosis:
- Dermoscopy can aid in early diagnosis and biopsy site selection, showing features such as follicular plugging (82.1%), arborizing blood vessels (85.7%), whitish scales (89.3%), and pigmentation (82.1%). 8, 6
- Reflectance confocal microscopy (RCM) shows promise for biopsy site selection by identifying interface changes and inflammatory infiltrates, though it cannot distinguish lymphocyte subtypes. 9
Critical Pitfalls to Avoid
- Do not rely solely on clinical appearance, as many inflammatory and infectious disorders can present with similar features. 1
- Do not skip histopathological confirmation even when clinical features are highly suggestive, as the differential diagnosis is broad. 1, 4
- Ensure adequate biopsy depth and size (at least 4 mm punch) to capture both superficial and deep dermal changes characteristic of DLE. 1