S4C21P13PLC


S4C21P13-1: In this field, compact hyperkeratosis, basal unit hyperplasia, spongiosis, and spotty, intraepidermal infiltrates of lymphoid cells are features. There is focal liquefaction degeneration of the basal layer of the epidermis, but the focal nature of the process is a feature in keeping with spongiosis (as opposed to a lichenoid process). The distinctions between spongiosis, and a primary lichenoid process are arbitrary; in part, they are defined by the focality of the spongiotic process. A similar process in a more diffuse pattern would likely be characterized as lichenoid. Spongiotic patterns are acceptable in the general category of pityriasic disorders. The clinical impression for this case was childhood pityriasis lichenoides chronica (PLC-8627: La Derm)

S4C21P13-2: In this area in the same case of PLC, the lesion shows hyperplasia of both the basal and the superficial units of the epidermis. The focal process is basically spongiotic. Atypia, at this magnification, is not a feature of the epidermal infiltrate.


S4C21P13-3: At a higher magnification, the epidermis shows parakeratosis, spongiosis (inter-cellular, edema), and focal aggregates of lymphocytes and histiocytes among keratinocytes. The histiocytes are dendritic in character; they have rather pale cytoplasm. They are prominent in the rounded, cellular defect outlined by green arrows. Chromatin patterns of the nuclei of the dendritic histiocytes are delicate. These nidi, which are outlined by arrows, are rounded in the manner of spongiotic vesicles, but are clearly cellular. They seem to be somewhat intermediate between spongiotic vesicles and apoptotic foci. The nuclei of lymphoid cells are small, but irregular in outline (mild T cell dysplasia of indeterminate type).

S4C21P13-4: A second case of childhood “PLC” (La Derm-8629) is focal in nature at the tips of scattered dermal papillae, but there is a slight numerical accentuation of lymphoid cells among keratinocytes. For some observers, who place great emphasis on pattern analysis at low magnifications, the focal richness of the epidermal infiltrates might be sufficient to be cited as the basis for a diagnosis of “cutaneous T cell lymphoma.” An attempt to defend such a position would require the promotion of a contention, rather than an elaboration of an established criterion. In any case, the richness of the infiltrate provides a lichenoid quality and, again, the similarities of spongiotic and lichenoid processes are demonstrated. With the conflicts as to the nature of the epidermal patterns, a suggestion that the pattern is pityriasic might be appropriate.

S4C21P13-5: At a higher magnification, the epidermal infiltrates show some degree of atypia; there is variation in nuclear size and outline. Nuclear chromatin is dense. There is a small cluster of extravasated red blood cells at the dermal-epidermal interface; pityriasic qualities are represented.

S4C21P13-6: At a higher magnification, the nuclear aberrations are evident. There are transformed T lymphocytes of ambiguous type. The process qualifies as a mild T cell dysplasia of indeterminate type. The cells at the tips of green arrows have enlarged, convoluted nuclei.

S4C21P13-7: The dermal infiltrates also qualify as a mild T cell dysplasia of indeterminate type. There is variability in nuclear size and outline.

S4C21P13-8: Childhood pityriasis lichenoides chronica.

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