Subacute CLE (SCLE) is an exanthematic skin condition with a typical clinical appearance (diagnosis can often be made before the presence of Ro/SSA antibodies is documented) that is localized at the trunk and the extensor aspects of the upper extremities, more rarely in the face and neck (Sontheimer et al. 1979). Lesions have an intermediate morphology between DLE and SLE: they are erythematous flat plaques, much thinner than DLE, with some dry scaling but without adherent scales and hyperkeratotic follicular plaques. There is a tendency for central regression (which often results in annular lesions), but there is no full-blown atrophy or scarring and depigmentation (Fig. 11.3A). Patients with SCLE only rarely have systemic symptoms, but there is a clear history of photosensitivity.
Psoriasis (Fig. 11.3B) is the skin disorder that most closely resembles SCLE. The size, nummular shape, and color of the individual lesions may be quite comparable, but the predilection sites are different (SCLE has no lesions on the knees, elbows, scalp, and sacral areas), as are the types of scaling (psoriasiform vs small and thin lamellar) and the presence of slight (mostly central) atrophy in SCLE.
Fig. 11.3. A Annular subacute cutaneous lupus erythematosus lesions. Except for their slight central atrophy, almost indistinguishable from annular psoriasis (B). C Erythema annulare centrifugum: no epidermal involvement (scaling and atrophy)
Pityriasis rosea differs from SCLE by its acute onset, its more inflammatory character, its typical distribution on the trunk ("christmas tree-like"), and its peripheral collerette-like scaling.
Tinea corporis and superficial trichomycosis may be confused with SCLE because they represent annular lesions with a peripheral erythematous scaly margin. Differences are in that the mycotic infections rarely arise in an exanthematic fashion on the trunk (except in immunodeficient individuals), and they are pruritic. Potassium hydroxide preparations quickly resolve diagnostic problems.
Erythema annulare centrifugum (Fig. 11.3C; see above) and other figurated erythemas may clinically (and histopathologically) look similar to SCLE, and indeed they have been equated with this disorder by some authors (Ruzicka et al. 1991). They lack epidermal involvement, however, except of some cases of erythema annulare cen-trifugum that exhibit a distinctive pattern of scaling at the inner slope of the erythe-matous margin.
Granuloma annulare, especially the superficial generalized variant (see previously herein) may show some similarity to SCLE; likewise,there is no epidermal involvement.
Neonatal LE (NLE) is caused by maternal Ro/SSA antibodies and therefore shares many features with SCLE: well-demarcated, annular skin lesions with little tendency for atrophy arising in mainly light-exposed areas (photosensitivity) and combined with anemia and heart block. This transient LE syndrome must be distinguished from seborrheic dermatitis, which is also found in the first months of life but shows a predilection for the scalp (where it is more desquamative than NLE) and the intertriginous regions (where it is more inflammatory and at times oozing). NLE is further distinguished by larger, stable polycyclic lesions with moderate central atrophy.
Differential diagnosis of neonatal NLE also includes atopic dermatitis, which usually sets in at a later time and presents as a more widespread eruption with predilection of the face, extremities, and intertriginous areas. There is pruritus and skin irritability. Neonatal psoriasis may look similar to neonatal LE, but it lacks annular patterns and central atrophy.
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Do You Suffer From the Itching and Scaling of Psoriasis? Or the Chronic Agony of Psoriatic Arthritis? If so you are not ALONE! A whopping three percent of the world’s populations suffer from either condition! An incredible 56 million working hours are lost every year by psoriasis sufferers according to the National Psoriasis Foundation.