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Atypical lymphocytic infiltrates of the dermis: The category of the lymphocytic infiltrates of the dermis should be restricted to disorders in
which the chief histologic features is a uniform perivenular infiltrate of mature lymphocytes. It should exclude processes with significant
alterations at the dermal-epidermal interface. Some of the features of a cell-poor lichenoid reaction are acceptable, especially in the category of polymorphic light eruption. For some examples of PMLE, the lichenoid changes may be sufficiently developed to warrant a recommendation to rule out lupus erythematosus. In the general category of lymphocytic infiltrates of the dermis, some degree of a lymphohistiocytic collagenosis is acceptable; in making this concession, a degree of mucinosis also must be accepted. Processes with nodular lymphoid aggregates should be excluded. In this approach, acceptable disorders include: polymorphic light eruption (mild patterns of liquefaction degeneration at the dermal-epidermal interface and papillary dermal edema are acceptable), erythema annulare centrifugum (spongiotic epidermal patterns are acceptable in the superficial variant; eosinophils are occasionally a feature of the infiltrates), and some examples of drug eruption (the pattern of a lymphocytic vasculitis, often with an eosinophilia, is a common presentation for a drug eruption and could be characterized as a lymphocytic infiltrate). Occasional examples of LE may qualify but, as such, the patterns are not diagnostic. Cutaneous infiltrates of lymphocytic leukemia and lymphoma may be distributed in the pattern of a lymphocytic infiltrate. Early lesions of granuloma annulare may be mistaken for a lymphocytic infiltrate.
I have reserved the category of the lymphocytic infiltrates of Jessner for special consideration. At a histologic level, it has mostly been a mystery to me. Often visiting authorities
have characterized a cutaneous lymphoplasia (a diffuse, or nodular infiltrate as a lymphocytic infiltrate of the dermis). When this has happened, I find their approach difficult to accommodate in my definition of a
lymphocytic infiltrate. I believe that the confusion relates to patterns which may be encountered in early lesions of cutaneous lymphoplasia (and often in the dermis at the periphery of a lesion of cutaneous
lymphoplasia [and evolving lymphomas]).
For a problematic lesion, in which there are minor deviations in histologic patterns from the patterns defined with the above criteria, the deviations should be given recognition; such
lesions might be assigned to a atypical category (S15C6P1-1-6, S15C6P2-1-4, S15C6P3-1-4, S15C6P4-1-5).
Currently, great emphasis is placed on the results of flow cytometric examinations and immunohistochemisty in the classification of lymphoid lesions. In the skin,
this approach has fostered a variety of lymphomas of the skin in which the immunohistochemical results are compared with those of nodal lymphomas; the results then are translated into a diagnosis that would have
relevance for a particular nodal lymphoma. As an example, follicular lymphomas of the skin are often diagnosed on the basis of the results of immunohistochemical stains, with apparent lack of regard for a
representation of established criteria for the histologic diagnosis of nodal follicular lymphomas. In this approach, representation of B and T cell zones is an
acceptable feature. Follicular components with relative little cytologic atypia, with mantle zones, and with tingible body macrophages are also acceptable. With these compromises, the sponsors then note that the follow-up studies are remarkable favorable with compared to the results for nodal lymphomas.
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