Mucha-Habermann disease (PLEVA)
Early
| Wedge-shaped, superficial and, sometimes, deep perivascular and interstitial infiltrate of lymphocytes |
| Lymphocytes and vacuolar alteration obscuring the dermoepidermal junction |
| Individual necrotic keratinocytes scattered within the epidermis, especially the lower half; few or many |
| Slight spongiosis and ballooning |
| Slight pallor in the upper part of the epidermis |
| Cornified layer basket-woven in configuration |
Fully developed
All of the features of early lesions plus:
| Wedge-shaped infiltrate of lymphocytes usually deep as well as superficial |
| Lichenoid array of lymphocytes in section from some specimens |
| Vacuolar alteration marked sometimes with separation along the dermoepidermal junction and, eventually, subepidermal vesiculation |
| Numerous individual necrotic keratinocytes within the epidermis; confluent necrosis sometimes, also in wedge shape |
| Spongiosis and marked ballooning resulting sometimes in intraepidermal vesiculation accompanied by reticular alteration; rupture of an intraepidermal vesicle also resulting in a subepidermal vesicle |
| Marked pallor at times in the upper part of the epidermis |
| Mounds of parakeratosis and/or scale-crusts usually housing neutrophils |