Perforating granuloma annulare.

BACKGROUND: Perforating granuloma annulare (PGA) is considered an histologic subtype of granuloma annulare (GA) and it is described as a very rare disease, usually of children, affecting the dorsum of the hands. Mechanisms leading to perforation are unknown. Our experience suggested a different clinical presentation, so we decided to review our patients and the cases published.

METHODS: We present six cases of PGA and review 52 PGA cases reported in the literature. Data regarding sex, age, time of evolution of disease, clinical features, laboratory findings, treatment, and follow-up were collected. The significance level was determined by the chi 2 or Student t test when appropriate.

RESULTS: The prevalence of PGA could be up to 5% of GA. Pustular-like lesions can be found in 26% of cases, and scars in 37%; papular, umbilicated, and crusted lesions being the most common finding. While PGA appears as a single lesion in only 9% of cases, and half of the patients are older than 30 years. In GA 50% of cases present as a single lesion and 80% of patients are younger than 30 years.

CONCLUSIONS: PGA is different to GA not only histologically but also clinically. It is a disseminated disease, affecting both children and adults, which is characterized by the presence of multiple papules, most of them umbilicated and/or crusted, and characteristically pustular lesions and scars. Histology suggests that the superficial localization of the necrobiotic granuloma leads to the epidermal perforation. Treatment is disappointing.