CELL-POOR LICHENOID PATTERNS

1. lupus erythematosus

2. dermatomyositis

3. graft vs host (including lymphocyte recovery)

4. drug

5. lymphocytic infiltrates (PMLE, etc.)

S5C6VA1-1 (left): Some of the disorders, which might be characterized as cell-poor lichenoid reactions, are listed in theTable. In general, the cell-poor variants are characterized by straight dermal-epidermal interfaces with effacement of the rete patterns. In part, this quality may be indicative of an arrest in formation of cells of basal keratinocyte type, with an abrupt transition from basal layer to cells having the characteristics of cells of the superficial unit of the epidermis (i.e., cells that are committed to terminal differentiation). The deficient basal unit may be less the result of lysis of cells (as in a lichen planus-like reaction) and more a manifestation of a conversion of cells to a specific phenotype, with a loss of expression of an important intermediate stage in the kinetics of the differentiation of epidermal keratinocytes.

6. rosacea

7. radiodermatitis

8. LS&A

9. senescent lichenoid reactions (e.g., T-cell dysplasias)

S5C6VA1-2 (right): The designation, “interface disorder,” generally is employed as a synonym for a lichenoid reaction, particularly of the cell-poor type. On the other hand, the subepidermal vesicular disorders also are variants of interface disease. In the interface disorders, great emphasis often is placed on submicroscopic structures of the basement membrane zone. In practice, damage to basal keratinocytes is basic to the ensuing morphologic features. It seems incongruous to place great emphasis on alterations in fine structure of interface components and then to ignore, as a significant factor, the features pointing to damage of basal keratinocytes.

S5C6VA1-3: The histiocyte has a significant role in the histogenesis of the lichenoid reactions. In this lesion of lupus erythematosus, an immunoreaction for KP-1(CD68) marks many of the cells in the infiltrates of the papillary dermis and at the dermal-epidermal interface; they are marked as activated histiocytes (blue arrows). Cells with elongated, wavy nuclei and scanty cytoplasm [red arrows] are migratory histiocytes. The histiocytes tend to congregate in linear arrays at the basement membrane level.

S5C6VA1-4: This lesion of pemphigus foliaceus provides a nice demonstration of the two functioning units of the epidermis. The cells of the superficial unit are reddish-pink (i.e., glycogen-rich); they are committed to terminal differentiation. Their long axes are parallel to the surface of the skin. Cells of the basal unit have their long axes perpendicular to the basement membrane. The interstitium of the basal unit is mucoid (greenish-blue). The mucoid avenues are inconspicuous in the superficial unit. The basement membrane is red; focally, it is reduplicated. The interstitium of the papillary dermis is blue (PAS-alcian blue stain); the blue interstitium is mucinous. This anatomic structuring of the epidermis is altered in a variety of fashions in a variety of interface diseases and in diseases of the epidermal interstitium.

Next Page

Previous Page

Up a Page

last two (green) items along bottom row to right are web sites; all others in cluster provide access to SECTIONS of this SITE.