Dermatology Online Journal

Asymptomatic annular pink papules on the trunk
Azadeh Shirazi, M.D.^a, Clay J. Cockerell, M.D.^b, Ailing Li, M.D.^b, Sylvia Hsu, M.D^c
Dermatology Online Journal 10 (1): 11

University of Kentucky, Lexington, Kentucky^a, University of Texas Southwestern Medical Center, Dallas, Texas^b, Department of Dermatology, Baylor College of Medicine, Houston, Texas^c. shsu@bcm.tmc.edu

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Clinical summary

Figure 1	Figure 2

A 19-year-old man presented with a 6-month history of an asymptomatic eruption on his trunk. The lesions comprised 6-mm annular pink papules with a pink raised border. These were located primarily on the lower back (Figs. 1, 2) and lower abdomen. The patient had no significant past medical history and was taking no medications.

Figure 3	Figure 4

Two biopsy specimens were obtained from the back (Figs. 3, 4). There was hyperkeratosis, acanthosis, hypergranulosis, liquefaction, basal liquefaction, scattered keratinocytes, and a band-like infiltrate of lymphocytes and histiocytes in the superficial dermis.

Based on the clinical and histologic findings, the patient was diagnosed with lichen planus (LP).

Discussion

Lichen planus is an inflammatory dermatosis of unknown cause involving skin and mucous membranes. There is a growing body of evidence that LP represents T-cell-mediated autoimmune damage to basal keratinocytes that express altered-self antigens on their surface [1]. Clinical observation and anecdotal evidence have long suggested a relationship between exposure to a number of exogenous agents (including viruses), genetic influences, and contact sensitizers. LP most commonly affects patients ages 30-60. It classically presents as violaceous, shiny, pruritic papules, with a predilection for wrists, lumbar region, eyelids, shins, scalp, and glans penis. Oropharyngeal involvement is seen in 40-60 percent of patients [1].

Annular lichen planus is a rare clinical variant with lesions characterized by a ring-like configuration. The presence of annular lesions in has been reported in up to 10 percent of LP [2]. The majority of these cases, however, comprise annular lesions found in conjunction with the more characteristic polygonal lichenoid papules [3, 4]. Reported cases of annular LP commonly present with asymptomatic lesions confined to the penis and scrotum, and mostly involve black patients [2, 5, 6]. To the best of our knowledge, this is one of the few reported cases of asymptomatic annular lichen planus with lesions localized to the trunk.

There have been many cases of annular atrophic lichen planus (AALP), however, this seems to be a separate entity [3, 7]. Although the lesions of AALP also demonstrate an annular configuration, they are characterized as small violaceous papules that slowly enlarge peripherally, forming an atrophic and hypopigmented center. The histologic examination of AALP consistently demonstrates an absence of elastic fibers in the center [7, 8, 9]. Friedman and Hashimoto proposed that the annular lesions in AALP may result from inflammatory-cell-induced elastolysis and peripheral spread of the disease [7].

In annular lichen planus, the lesions are thought to arise from the coalescence of small papules but may also form from central clearing of a peripherally expanding plaque [2, 6].

The histopathological examination of lesions allows for histological diagnosis in greater than 90 percent of cases. The two major findings in lichen planus are basal epidermal keratinocyte damage and lichenoid-interface lymphocytic reaction. The epidermal changes include hyperkeratosis, wedge-shaped areas of hypergranulosis, and elongation of the rete ridges that resemble a saw-tooth appearance [1].

Annular lichen planus does not have a distinct natural history. Spontaneous resolution of the lesions occurs in an average of 15 months, with recurrences reported in up to 17 percent of patients [2]. Initial therapies include topical and systemic corticosteroids, retinoids, and oral psoralen with UVA therapy.

References

1. Daoud, MS, Outtekjiw, MR. Lichen Planus. In Fitzpatrick TB, Eisen AZ, Wolff K, Austen KF, Goldsmith, LA, Katz SI, eds. Dermatology in General Medicine. New York, NY: McGraw-Hill; 1193: 463-464.

2. Barnette DJ, Curtin TJ, Yeager JK, Corbett DW. Asymptomatic penile lesions. Cutis 1993; 51: 116-118. PubMed

3. Cram DL, Muller SA. Unusual variants of lichen planus. Mayo Clin Proc 1966; 41: 667-88.

4. Voron D, MacVicar D: Annular lichen planus. Cutis 1973; 11: 635.

5. Matsuura C., Tsukifuji R, Shinkai H, Annular lichen planus showing a change in metallothionein expression on immunohistochemistry, Brit J Dermatol 1998; 138: 1043-1045.

6. Boyd AS, Neldner KH. Lichen planus. J Am Acad Dermatol 1991; 25: 593-619.

7. Friedman DB, Hashimoto K. Annular atrophic lichen planus. J Am Acad Dermatol.1991; 25: 392-394.

8. Patel RI, Reed WB. Annular atrophic plaques of the face and upper body. Cutis 1979; 24: 90-93.

9. Requena L, Olivares M, Pique E, Farina MC, Martin L. Annular atrophic lichen planus. Dermatol 1994; 189: 95-98.

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