2nd order laboratory parameters – depending on the results of history, physical examination and obligatory laboratory parameters – for differential diagnostic clarification.
- Small blood count
- Differential blood count
- Inflammatory parameters – CRP (C-reactive protein) or ESR (erythrocyte sedimentation rate).
- Infectious serology
- Microscopic fungal detection from the marginal area of the altered skin site (smears, skin scrapings, nail material).
- Epicutaneous test (synonyms: patch test, patch test) – in this test, a patch is applied to the patient’s skin, which contains various allergens; after two to three days, the patch can be removed and the test can be assessed
- If necessary, skin biopsy
