Quiz 36: What is your diagnosis?

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Diagnosis: Quiz 36

Quiz 36

Answer:  Nummular dermatitis with features of lichen simplex chronicus

Criteria for diagnosis clinically: Coin-shaped, slightly scaly and crusted, violaceous papules and plaques, some of which have become confluent and joined by signs of lichenification, are those of nummular dermatitis on which lichen simplex chronicus has been imposed.

Differential diagnosis clinically: There is none.

Criteria for diagnosis histopathologically: The constellation of a perivascular infiltrate of lymphocytes, loci of subtle spongiosis in zones of infundibular hyperplasia, the latter being accompanied by surface epidermal and eccrine ductal hyperplasia, and prominent parakeratosis in conjunction with orthokeratosis is that of nummular dermatitis. A combination of a papillary dermis widened considerably by coarse bundles of collagen arrayed in vertical streaks and of compact orthokeratosis is that of lichen simplex chronicus.

Differential diagnosis histopathologically: The spongiotic process could be allergic contact dermatitis, as well as nummular dermatitis, reference to features clinical being crucial in differentiation of one from the other.

Clinicopathologic correlation: The papules and plaques are formed of infiltrates of inflammatory cells, epidermal and eccrine ductal hyperplasia, and a papillary dermis widened by coarse bundles of collagen in vertical streaks; the scale consists mostly of cells parakeratotic; and the lichenification is a consequence of the combination of a papillary dermis being widened by coarse bundles of collagen in vertical streaks and a stratum corneum being compactly orthokeratotic.

Options for therapy predicated on knowledge of histopathologic findings: The spongiotic dermatitis can be managed by application of a corticosteroid applied topically and the lichen simplex chronicus by interrupting the rubbing. Because nummular dermatitis tends to be pruritic maddeningly, the aim of treatment should be to bring that inflammatory process under control, it being responsible for the agitating pruritus. The reality is that nummular dermatitis behaves in fashion unpredictable and can be exceedingly difficult to subdue by application of topical corticosteroid. What must be avoided at all costs is systemic administration of a corticosteroid, that being not only an exercise in futility, but a hazard to the patient's general health if given long-term.

1) Lichen simplex chronicus is the term given to lichenification of skin that comes into being as a consequence of rubbing hard, back and forth, for many months or even years. The rubbing can be imposed on an underlining process, in this instance, nummular dermatitis, or on skin normal morphologically.

2) No small number of inflammatory processes can be complicated by the effects of rubbing persistently for long, among those spongiotic processes being allergic contact dermatitis and dyshidrotic dermatitis, as well as nummular dermatitis, lichen planus situated on the anterior surface of the legs (the result being hypertrophic lichen planus), and macular/papular amyloidosis (the result being lichen amyloidosis). In each of those instances, the basic process pathologic can be recognized for what it is histopathologically, in addition to the signs of lichen simplex chronicus, the latter being thickening of the skin, hyperpigmentation, and accentuation of the pattern of dermatoglyphics.

3) The most common presentation of lichen simplex chronicus is not in the context of a pre-existing vexingly pruritic inflammatory process, such as nummular dermatitis or lichen planus, but a response to itching as a symptom of atopy or as a manifestation of anxiety. When the atopic state is responsible for itching, the signs of lichen simplex chronicus in association with evidences of excoriation, i.e., erosions, ulcerations, and crusts, then are designated conventionally "atopic dermatitis," it being factitious entirely (which is why Brennenkmeijer et al. in the most recent issue of the Journal of the American Academy of Dermatology  (2008;58:407) could write this sentence, correct, but staggering nonetheless: "To date, there is no gold standard for the diagnosis of AD [atopic dermatitis]". That unabashed statement comes 70 years after Sulzberger gave the name "atopic eczema" to the condition.

4) Lichen simplex chronicus and excoriations also can appear in persons who are not atopic genetically (who do not have a personal or family history of allergic rhinitis/conjunctivitis or allergic asthma and whose levels of IgE are not elevated markedly). On grounds morphologic alone, lichen simplex chronicus and excoriations present in an atopic patient (so-called atopic dermatitis) cannot be distinguished from those same lesions in a person who is not atopic. If, however, a glance is cast at the face of the individual affected, it often is possible to read in it unquestionable evidences of an atopic, namely, "allergic shiners" in the skin around the eyes, Dennie's lines (so-called mongoloid pleat), and the "salute sign" (a horizontal line just above the tip of the nose that results from pushing up the base of the proboscis with the tip of a middle finger in an effort to relieve itching. A light stroke across a pink cheek of such a person often induces "white dermographism," and a query about whether the tongue is used to rub the palate in an attempt to quell itching during the spring and fall (the major seasons for inhalant allergy) is answered often in the affirmative. All of the aforementioned are signs indubitable of being atopic.

5) Because the section of tissue pictured here is oriented obliquely, there seem to be interconnections at the base of hyperplastic infundibula and eccrine ducts that, in actuality, are independent of one another. The surface epidermis is not hyperplastic, only the infundibular epidermis. Sometimes the resulting pseudocarcinomatous hyperplasia is misconstrued as squamous-cell carcinoma, but the former condition is not characterized at the periphery of elongations by nuclei of keratocytes that are crowded, pleomorphic, and heterochromatic.

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