Patch-type granuloma annulare

ARTICLE

Auteur(s) : Ricardo Coelho¹, Rodrigo Carvalho², Ana Rodrigues², Ana Afonso³, Jorge Cardoso²

¹Dermatology Department, Hospital de Faro
²Dermatology Department, Hospital de Curry Cabral
³Pathology Department, Hospital de Curry Cabral

A 74-year-old white woman was referred to our department with a 1-year history of four large asymptomatic lesions on her thighs. The lesions began as small erythematous patches and subsequently increased in diameter. She had a history of arthritis, treated for the preceding 3 years with naproxen.

Examination of the posterior thighs revealed four large (between 3 × 2 cm and 17 × 14 cm) erythematous, minimally scaly, oval patches, with no induration. One of the lesions had light central clearing (figure 1). Physical examination was otherwise unremarkable. The initial clinical impression was parapsoriasis, and a biopsy specimen was obtained. Histopathological examination revealed a moderate superficial and mid-dermal interstitial infiltrate of lymphocytes and histiocytes, and mucin between collagen fibers; these findings are consistent with the interstitial variant of granuloma annulare. Further investigations were unremarkable. The diagnosis of patch-type granuloma annulare was made, and the patient was treated with betamethasone ointment twice daily for 4 weeks with no improvement. We did not find any regression of the lesion after biopsy. Because the lesions were asymptomatic and caused no anxiety to the patient, topical medication was discontinued.

Granuloma annulare is a benign, self-limited condition; the cause is unknown and the pathogenesis is poorly understood. There are several clinical variants of granuloma annulare: localized, generalized, subcutaneous, perforating, linear, and patch types. There is an overlap between variants, and more than one morphological type may exist in the same patient. This patient had a rare, recently described granuloma annular variant named patch granuloma annulare [1]. It appears as asymptomatic erythematous to brown patches, with or without minimal scale, that may have an annular configuration on the trunk or proximal extremities. There is no evidence of papules, scales, or induration [2]. As with other forms of granuloma annulare, there is a female predominance. There is also a possible association with drug reaction (which may have been present in our patient) [1-3].

A high index of suspicion is necessary to make the diagnosis. The differential diagnosis of patch-type granuloma annulare includes morphea, erythema annulare centrifugum, and parapsoriasis. Pathologically, this entity is characterized by an interstitial pattern of mononuclear cellular infiltration with scattered histiocytes between collagen fibers; there is mucin deposition between collagen bundles that can be highlighted by Alcian blue and colloidal iron stains [4]. Necrobiotic areas are usually absent. In cases related to drug reactions, eosinophils and some lichenoid changes at the dermal-epidermal interface are present. Histological differential diagnosis includes necrobiosis lipoidica and interstitial granulomatous dermatitis. Systemic therapy is unnecessary because of the relatively limited involvement and asymptomatic nature of the lesions. It is reported that patch granuloma annulare will respond to the same therapy as other types of granuloma annulare: cryotherapy, topical and intralesional corticosteroids for localized disease, and photochemotherapy, isotretinoin, dapsone, or antimalarials for generalized disease. Resolution of patch-type granuloma annulare after biopsy has been reported [5].

In conclusion, we present a rare and recently described variant of granuloma annulare characterized by patches of erythema on the extremities and trunk that lack the usual clinical findings but display the classic histopathological findings of interstitial granuloma annulare.

Acknowledgements

References

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3 Font M, Botargues N, Bonilla X, Vilá P. Granuloma anulare maculoso. Siete nuevos casos. Med Cutan Iber Lat Am 2004 ; 32 : 23-6.

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5 Levin NA, Patterson JW, Yao LL, Wilson B. Resolution of patch-type granuloma annulare lesions after biopsy. J Am Acad Dermatol 2002 ; 46 : 426-9.