S4C10VA2VisualAids

PITYRIASIC DISORDERS

1. spongiotic disorders:

a. pityriasias rosea

b. some of examples of pityriasis lichenoides chronica

2. lichenoid lymphocytic vasculitides, including 2nd lues

a. pityriasis lichenoides et varioliformis acuta (prominent parakeratosis)

b. some examples of pityriasis lichenoides chronica

S4C10VA2-1: Examples of disorders with pityriasic qualities are listed.

SPONGIOTIC LICHENOID DERMATITIS

(CELL-RICH EPIDERMAL PATTERNS WITH SPONGIOSIS AND SPONGIOTIC VESICULATION)

1. hyperplasia of basal unit with expansion of epithelial interstitial matrix in spongiotic patterns

2. often associated with deficient superficial epidermal unit (poorly developed granular layer), parakeratosis, and clusters of neutrophils in the zones of parakeratosis

3. open epidermal avenues give lymphocytes and histiocytes ready access to the epidermal domain.

4. necrosis of individual keratinocytes

5. perivascular infiltrates in vasculitic patterns (perivenular infiltrates in reticular dermis)

S4C10VA2-2: the features of pityriasic variants of lichenoid lymphocytic vasculitides are listed in the above Table.



S4C10VA2-3: Features of the pityriasic variations are represented in the above drawing. In all examples, the basal unit is hyperplastic and the superficial unit is poorly developed. Zones of parakeratosis are along the surface and may be rather uniform in the lichenoid and psoriasiform variants. Light pink cells are members of the superficial unit. Bright red cells are dying keratinocytes; they would qualify as representatives of the process of pathologic apoptosis. Dendritic histiocytes are light brown. Lymphocytes appear as dots. Cells of the basal unit of the epidermis are blue.

S4C10VA2-4: This representation of a lesion of pityriasis lichenoides acuta places emphasis on an altered superficial unit in which the turnover of cells is accelerated. In this rapid turnover, cells, that are committed to terminal differentiation, find their way to the surface without completing the process of terminal differentiation; the product at the surface is parakeratotic. An increased turnover of cells in the basal unit, with a more rapid transfer of cells to the superficial unit, will compromise the ability of cells of the superficial unit to “die” properly.

The basal unit is expanded. As a consequence, rete patterns are often preserved and individual rete ridges may even be expanded. The diffuse character of the infiltrates contrast sharply with the limited, focal involvement in a spongiotic process.

Back one CHAPTER

Next CHAPTER

Up to next tier

Note: movements with the above buttons are spatial rather than temporal