Asymptomatic erythematous plaque.

CASE

A 44 year old woman presented for evaluation of a new, slightly raised red rash on the right side of chest that developed in the spring. Physical examination revealed an edematous, red- to pink erythematous, non-tender plaque involving the right side of chest [Figure 1]. No surface change was noted. She did not have any other similar lesions. A skin biopsy was obtained for histopathologic analysis [Figures 2–5].

Figure 1

An edematous, erythematous plaque involving the right chest

Figure 2

Superficial and deep perivascular and periadnexal lymphocytic infiltrate extending into the subcutis. H and E, original magnification ×40

Figure 5

No stratum corneum alterations are present and the dermal-epidermal junction is normal. Hematoxylin and eosin staining, original magnification ×400

Superficial and deep lymphocytic infiltrate tightly hugging vessels and adnexae. H and E, original magnification ×100

The infiltrate consists of monomorphic lymphocytes. Subtle interstitial mucin is present. H and E, original magnification ×200

The most likely diagnosis is:

Erythema annulare centrifugum

Granuloma annulare

Lupus erythematosus tumidus

Polymorphic light eruption

Answer: 3. Lupus erythematosus tumidus

DISCUSSION

Lupus erythematosus tumidus (LET) was first described by Gougerot and Burnier in 1930 as a smooth, infiltrated, erythematous plaque without scale or other epidermal changes.[1] LET was not included in the classification of cutaneous lupus erythematosus (CLE) proposed by Gilliam[1] in the 1970s that categorized CLE into three main clinical types: Chronic CLE (CCLE), which included discoid lupus erythematosus (DLE) as a major type, and subacute CLE (SCLE) and acute CLE (ACLE) based on clinical symptoms, duration, histologic and serological findings, although overlap is known to exist. But, after the revisions and modifications of Gilliam's original classification, LET has been included as a subgroup of CCLE based on similarity in prognosis and minimal association with autoantibody production.[12] A fourth category, intermittent CLE, was proposed to distinguish between LET, which does not leave scarring or atrophy on resolution, and other forms of CCLE, such as DLE, that classically resolve with residual tissue damage. The category of intermittent CLE has yet to gain wide acceptance.[123]

LET affects females and males in roughly equal proportion[4] with a mean age of onset in the 4th decade of life.[1] Clinically LET presents as round to annular erythematous, infiltrated papules and/or plaques favoring the face though any sun-exposed areas may be affected. The lesions usually develop after exposure to sunlight with a latency period over 24 hours and have a tendency to persist for months. Provocative phototesting with UVA and/or UVB may cause new lesions to develop in a majority of patients.[4] LET can be clinically differentiated from SCLE and DLE by the absence of epidermal alterations such as atrophy, follicular plugs, desquamation and erosions.[12] In addition, LET lesions heal without scarring, atrophy or dyspigmentation.[1] LET typically is not associated with systemic lupus erythematosus (SLE) and antinuclear, anti-Ro, anti-La, and anti-DNA antibodies are usually negative.[1]

Histopathologically, LET is characterized by a superficial and deep periadnexal and perivascular lymphocytic infiltrate and increased dermal mucin.[1] Most cases lack substantive alterations of the epidermis such as follicular plugging or hyperkeratosis though epidermal atrophy and mild vacuolar degeneration of the basal layer are reported in 30-50% of cases in one report.[5] Direct immunofluorescence is usually negative but may demonstrate deposition of 1 or 2 immunoreactants insufficient for a diagnosis of a lupus band along the basement membrane.[145]

Answer choice 1, erythema annulare centrifugum (EAC) is not the preferred choice for several reasons. First, the clinical lesion lacks surface change that is typical of EAC where it is seen as a “trailing scale” within an annular, relatively flat plaque lacking induration. Next, though EAC is microscopically characterized by a tight perivascular “cuff” of lymphocytes, the infiltrate involves the superficial vascular plexus in most cases. Lastly, dermal mucin deposition is not a feature of EAC.

Answer choice 2, Granuloma annulare (GA) presents with skin colored to red-brown grouped papules that may coalesce in an annular or arciform arrangement. The microscopic features are distinct, consisting of either interstitial, necrobiotic or, rarely, sarcoidal granulomas. Mucin is increased in the granulomas, but is not deposited diffusely throughout the dermis. For these reasons, GA is not a valid answer.

Answer choice 4, polymorphic light eruption, is not typically associated with dermal mucin. A range of histopathological findings may be present.[167] Polymorphous light eruption (PMLE) is a UV-induced dermatitis of papular, papulovesicular, or plaque like appearance. PMLE develops 24-96 hours after sunlight exposure and, in contrast to LET, improves within a few days if there is no further UV exposure. The eruption favors the upper trunk and extensor forearms while sparing the face and hands in most cases. Provocative UV testing results are unpredictable. Histopathological features include mild spongiosis, marked edema in the papillary dermis, and superficial and deep perivascular lymphocytic infiltrate. Distinguishing features from LET include prominent papillary dermal edema and lack of interstitial mucin deposits.[4]

Reticular erythematous mucinosis (REM) is considered by many as synonymous with or closely related to LET as there is significant overlap in the clinical and histopathologic features of the diseases. Clinically REM presents as reticulated to solid erythematous patches or infiltrated plaques on the upper trunk of predominantly young to middle-aged women. The eruption is typically related to intense sun exposure. Histopathological features include periadnexal and perivascular lymphocytic infiltrate and prominent interstitial mucin. The epidermis is usually normal though spongiosis and focal lichenoid inflammation have been reported. Serologic tests for lupus are negative. Similar to LET, antimalarials are considered first line treatment for REM.[67]

LET usually follows a benign course.[2] Patients respond quickly to antimalarials or medium potency topical corticosteroids. Relapses may be prevented with sun avoidance techniques. Systemic corticosteroids and immunosuppressants can be considered in refractory cases.[24]