Sir,

Annular lichen planus is an uncommonly reported variant of lichen planus, especially on the penis [1]. Herein, we report a case of penile annular lichen planus induced by artificial pearls.

A 42-year-old, circumcised male presented to our hospital with asymptomatic, annular lesions of the glans penis. Around one month prior to presentation, he reported a history of inserting artificial pearls inside his penis by stainless steel. He denied a history of drug intake or a personal history of hepatitis C. A physical examination revealed multiple, reddish-purple, annular plaques with central atrophy on the glans penis (Fig. 1a). Inguinal lymph nodes and other mucocutaneous lesions were absent.

Figure 1: Annular lichen planus: (a) multiple, reddish-purple, annular plaques with central atrophy; (b) after two-week treatment with tacrolimus 0.1%.

On the day of the visit, a rapid plasma reagin (RPR) test, Treponema pallidum hemagglutination (TPHA) test, and hepatitis C antibody test were all negative. Fungal microscopy of the glans penis was negative. A patch test was not performed due to its unavailability.

A histological examination revealed a lichenoid reaction pattern characterized by a combination of degeneration of the basal layer of the epidermis and a band-like lymphocytic infiltrate obscuring the dermal-epidermal junction. There was irregular, epidermal hyperplasia forming a characteristic saw-tooth appearance with wedge-shaped hypergranulosis (Fig. 2a). The basal layer of the epidermis exhibited vacuolar degeneration. The inflammatory infiltrate was chiefly lymphocytic and formed a dense band in the superficial dermis (Figs. 2b and 2c).

Figure 2: Histological findings: epidermal hyperplasia forming a characteristic saw-tooth appearance with wedge-shaped hypergranulosis (H&E, 40×); (b-c) the basal layer of the epidermis exhibiting vacuolar degeneration and the inflammatory infiltrate chiefly lymphocytic and forming a dense band in the superficial dermis (H&E, 100× and 200×).

The diagnosis of annular lichen planus was confirmed and tacrolimus 0.1% was applied twice a day for two weeks. The lesions resolved significantly (Fig. 1b).

Annular lichen planus is one of the rarest variants of lichen planus, accounting for 3-7% of cases. The lesions present as ring-formed, violaceous plaques with or without central atrophy on the intergious sites, the penis and the scrotum [2].

The pathogenesis of lichen planus remains unknown. However, it is related to virus infection (hepatitis C), drugs (antimalarials, ACEIs, thiazide diuretic, NSAIDs, quinidine, beta-blockers, tumor necrosis factor-alpha inhibitors, gold), and contact allergens (mercury, copper, and gold) [3]. Our patient presented the annular lesions on the glans penis after one month of penile implants; therefore, it could be linked to the etiology.

The differential diagnosis of a penile annular lesion includes annular psoriasis, granuloma annulare, dermatophyte infection, and annular secondary syphilis [4]. Annular psoriasis is characterized by annular, erythematous plaques with scaling borders and central clearing, especially a positive Auspitz’s sign. Therefore, annular psoriasis was excluded due to the negativity of the Auspitz’s sign and the non-scaling borders of the lesions. Fungal microscopy and syphilis tests were negative. The diagnosis of a dermatophyte infection and annular secondary syphilis were also excluded. Granuloma annulare is histologically characterized by necrobiotic degeneration of dermal collagen surrounded by an inflammatory reaction, while the band-like lymphocytic infiltration at the dermal-epidermal junction is commonly seen in annular lichen planus.

The first-line treatment of genital lichen planus is topical corticosteroids. Alternative treatments include topical calcineurin inhibitors, topical calcipotriol, systemic corticosteroids, acitretin, isotretinoin, methotrexate, hydroxychloroquine, dapsone, cyclosporine, azathioprine, and mycophenolate mofetil [2,5].

Annular lichen planus is a rare manifestation of lichen planus, which may be misdiagnosed as other annular skin lesions.

REFERENCES

Notes

Conflict of Interest: The authors have no conflict of interest to declare.

 

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	Ngo Binh Trinh http://orcid.org/0000-0002-3829-3115 Giang Huong Tran http://orcid.org/0000-0002-9480-4602