Mossy and interfacial dermatitis are histopathologic descriptions. Mossy dermatitis is an inflammatory dermatosis characterized by a band-like infiltration of inflammatory cells, mainly lymphocytes, in the superficial dermis, and the infiltration of inflammatory cells often leads to a blurring of the epidermal-dermal interfacial interface. Interfacial dermatitis is an inflammatory skin disease characterized by liquefied basal cell degeneration, basal cell necrosis, and infiltration of inflammatory cells in the superficial dermis, and this characteristic pathological change also leads to blurring of the epidermal-dermal boundary. The above two conditions are not mutually exclusive, most of the mossy changes are accompanied by the changes of interface dermatitis, however, some of the skin diseases characterized by interface dermatitis changes do not have the characteristics of mossy dermatitis, sometimes for the convenience of clinical and pathological description, often speak of the two collectively as interface dermatitis. Linlin Xin, Department of Dermatology, Shandong Qianfo Mountain Hospital
1. Lichen planus
Lichen planus is the most typical lesion in lichenoid dermatitis. The histopathology of lichen planus
It is characterized by hyperkeratosis of epidermis, wedge-shaped thickening of granular layer, hypertrophy of spiny layer, liquefied degeneration of basal cells, band-like infiltration of dense lymphocytes in the superficial dermis, colloidal vesicles and pigment incontinence visible in the superficial dermis.
Inflammatory cell infiltration, follicular dilatation and keratocyst formation can be seen in the lower part of the hair follicle and around the papillae in the early stage of hair flatulent moss. The adjacent epidermis between hair follicles may have a typical mossy infiltrate or may be normal. Sometimes liquefied degeneration of basal cells, colloid vesicles and pigment incontinence may be evident.
Pigmented lichen planus is characterized by epidermal thinning, basal cell vacuolation changes, pigment incontinence, and a banded infiltrate of lymphocyte-dominated inflammatory cells in the superficial dermis.
Hypertrophic lichen planus is characterized by significant hyperkeratosis and hypertrophy of the spinous layer, and inflammatory cell infiltration in the dermis is often accompanied by scar formation.
Oral lichen planus has the characteristics of general lichen planus, but may have incomplete keratinization, thin epidermis, more significant liquefied degeneration of basal cells, and infiltrating inflammatory cells in addition to lymphocytes and histiocytes, plasma cells are common.
In addition to the characteristics of general lichen planus, blisters or macules can be seen under the epidermis, mainly due to high edema, destruction of basement membrane, and severe liquefaction and degeneration of basal cells.
2. lichenoid keratosis
The histological changes of lichenoid keratosis are characteristic of lichen planus, showing hyperkeratosis, thickening of the granular layer, and spicules.
The dermis has dense inflammatory cells infiltrating in bands, the infiltrating cells are mainly lymphocytes, histiocytes, a few plasma cells, occasionally eosinophils, colloid vesicles and pigment incontinence are common. The histological changes of this disease differ from those of lichen planus in that focal keratosis is visible in the stratum corneum in varying degrees.
3. glossy moss
The histopathological changes of glossy moss are not characterized by moss-like changes in the early stage, but mostly in the dermis.
The papillary layer is infiltrated with inflammatory cells mainly lymphocytes. The typical rash is well-defined, and a single papule involves only 4-5 dermal papillae, showing epidermal atrophy, central depression, inflammatory cell aggregation in the superficial dermis in the shape of a sphere, and the epidermal protrusions on both sides are prolonged in the shape of a ball, and the epidermal basal cells above the infiltrating cells are liquefied and degenerated, and colloid vesicles can be seen, and the infiltrating cells include lymphocytes, histiocytes, eosinophils, neutrophils, and multinucleated giant cells. Rarely seen.
4. linear moss
The main histopathological feature of thread-like moss is the infiltration of inflammatory cells in the upper dermis, which lacks
The main histopathological feature of linear moss is inflammatory cell infiltration in the upper dermis, which lacks specificity and can be manifested as mossy dermatitis, interface dermatitis or spongiform edema dermatitis. The epidermis is generally normal or mildly hypertrophied with incomplete keratinization, intercellular edema, and necrotic keratin-forming cells, mild liquefaction degeneration of basal cells or no liquefaction degeneration of basal cells, and dense lymphocytic infiltration around the superficial dermis and superficial and deep blood vessels and appendages.
5. Fixed drug rash
The histological features of fixed drug rash are mossy, usually severe, with epidermal basal
There is often significant necrosis of the epidermal basal cells and the keratin-forming cells above, liquefied degeneration of the basal cells, banded infiltration of inflammatory cells in the superficial dermis, significant pigment incontinence, and subepidermal blistering when the lesions are severe.
6. sclerosing atrophic moss
Typical sclerosing atrophic moss lesions show epidermal atrophy and thinning, basal cells liquefaction
There is a wide hyaline-like deformation band in the superficial dermis, and an infiltrative band with lymphocytes and histiocytes can be seen below the hyaline-like degeneration band. The disease has common histopathological features with lichen planus, both of which have liquefied degeneration of basal cells and band-like infiltration of inflammatory cells in the dermis. However, the inflammatory cells in the dermis of sclerosing atrophic moss are mostly in the middle of the dermis, and there is no infiltrative zone between the epidermis. In contrast, the inflammatory cells in flat moss with band-like infiltration are located in the superficial layer of the dermis. Another prominent histopathological change in sclerosing atrophic moss is the alteration of collagen fibers in the superficial dermis, which shows high edema in the early stage and homogenization and sclerosis in the later stage.
7. lupus erythematosus
Histological changes in discoid lupus erythematosus are characterized by hyperkeratosis and follicular keratosis, liquefied degeneration of focal basal cells, and focal infiltration of dense lymphocytes in the superficial, middle and even deep dermis around blood vessels and around the appendages.
The histopathological changes of subacute cutaneous lupus erythematosus are similar to those of discoid lupus erythematosus, but the interfacial changes are usually more pronounced than in discoid lupus erythematosus, while the lymphocytic infiltration in the dermis is less severe than in discoid lupus erythematosus and is mainly around the superficial vessels. In addition, compared with discoid lupus erythematosus, subacute lupus erythematosus usually has edema in the superficial dermis and is generally free of epidermal hyperkeratosis and follicular keratosis.
The histopathological manifestations of SLE are similar to those of subacute cutaneous lupus erythematosus. When the liquefaction degeneration of basal cells is obvious and extensive, subepidermal fissures or subepidermal blisters may appear.
8. Graft-versus-host disease
Acute graft-versus-host disease is characterized by histologic changes of interface dermatitis, focal or diffuse liquefaction degeneration of basal cells, and dyskeratotic cells visible throughout the epidermis, which may be surrounded by one or several lymphocytes, forming a satellite-like cell necrosis phenomenon, which is a characteristic histopathologic manifestation of acute graft-versus-host disease. In severe cases, epidermal necrosis with subepidermal blistering may occur.
Chronic graft-versus-host disease is characterized by typical mossy dermatitis with hyperkeratosis, thickening of the granular layer, irregular proliferation of the spiny cell layer, vacuolar degeneration of the basal cells, banding of lymphocyte-dominated inflammatory cells in the superficial dermis, colloid vesicles, and pigment incontinence. The disease is sometimes difficult to distinguish from lichen planus, and focal keratinocyte necrosis can appear in the early stage of the disease, and the inflammatory cells in the banded infiltrate can be seen as plasma cells and eosinophils.
9. Erythema multiforme
The characteristic histopathological changes of erythema multiforme are apoptosis of epidermal keratinocytes, single or fused necrotic keratinocytes, intercellular sponge edema and intracellular edema of epidermis, liquefied degeneration of basal cells, sparse inflammatory cell infiltration of superficial dermis mainly by lymphocytes, edema of dermal papillae, and extravasation of erythrocytes in superficial dermis. In severe lesions, epidermal necrosis and widespread liquefaction and degeneration of basal cells form subepidermal fissures or subepidermal blisters.