Dermatitis
Author:
Mikael Häggström [note 1]
Sampling
- For punch biopsies, a size of 4 mm is preferred for most inflammatory dermatoses.[1]
- Panniculitis or cutaneous lymphoproliferative disorders: 6 mm punch biopsy or skin excision.[1]
A superficial or shave biopsy is regarded as insufficient.[1]
Fixation
- Generally: Buffered 4% formaldehyde.[2]
- Suspected immunologic disease:[3] Fixation for immunofluorescence, with for example Michel's solution.[2] For details, see immunofluorescense of skin tissues
Staining
3 H&E sections and one section with periodic acid Schiff (PAS)[notes 1][1]
- If suspected bacterial and fungal microorganisms, consider Gram stain and Gomori methenamine silver stain.[1]
Microscopic evaluation
One approach is to classify into mainly either of the following, primarily based on depth of involvement:[1]
- Epidermis, papillary dermis, and superficial vascular plexus:
- Vesiculobullous lesions
- Pustular dermatosis
- Non vesicullobullous, non-pustular
- With epidermal changes
- Without epidermal changes. These characteristically have a superficial perivascular inflammatory infiltrate, and can be classified by type of cell infiltrate:[1]
- Lymphocytic (most common)
- Lymphoeosinophilic
- Lymphoplasmacytic
- Mast cell
- Lymphohistiocytic
- Neutrophilic
Continue in corresponding section:
Non vesicullobullous, non-pustular lesions with epidermal changes
| Main types[1] | Characteristics | Image |
|---|---|---|
| Spongiotic dermatitis | ||
| Interface dermatitis | ||
| Psoriaform dermatitis |
Non vesicullobullous, non-pustular lesions without epidermal changes
Lymphocytic infiltrate
| Main conditions[1] | Characteristics | Image |
|---|---|---|
| Urticaria, lymphocyte predominant | Perivascular location. Mast cells are relatively sparse, potentially demonstrated with special stains, preferably tryptase stain. Extravasated erythrocytes are present in about 50% of the cases. No vasculitis.[4] | |
| Fungal skin infection | Visible fungus. Other signs depend on fungus species.[5] | |
| Pigmented purpuric dermatosis |
|
File:Histopathology of Schamberg disease.jpg |
| Erythema annulare centrifugum |
Deep lesions: Sharply demarcated perivascular mononuclear cell infiltrate in middle to deep dermis[7] |
File:Micrograph of erythema annulare centrifugum.jpg |
| Not otherwise specified | A lesion with superficial lymphocytic infiltrate without additional histopathologic characteristics can be due to for example drug reactions and insect bites.[1] |
Lymphoeosinophilic infiltrate
| Main conditions[1] | Characteristics | Image |
|---|---|---|
| Urticaria, lymphocyte predominant | Perivascular location. Mast cells are relatively sparse, potentially demonstrated with special stains, preferably tryptase stain. Extravasated erythrocytes are present in about 50% of the cases. No vasculitis.[4] | File:Micrograph of urticaria.jpg Dermal edema (solid arrows) and a sparse superficial predominantly perivascular and interstitial infiltrate of lymphocytes and eosinophils (dashed arrow) |
| Prevesicular stage of bullous pemphigoid | Image at right shows influx of inflammatory cells including eosinophils and neutrophils in the dermis (solid arrow) and blister cavity (dashed arrows), and deposition of fibrin (asterisks).[8] However, the diagnosis of bullous pemphigoid consist of at least 2 positive results out of 3 criteria:[9]
|
[[File:Micrograph of infiltrate in bullous pemphigoid.jpg|thumb| |
| Not otherwise specified | A lesion with superficial lymphocytic infiltrate without additional histopathologic characteristics can be due to for example drug reactions and insect bites.[1]
Notes
Main pageReferences
Image sources
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