Acquired Reactive Perforating Dermatosis is a Variant of Prurigo Nodularis.

Patients with chronic pruritus may develop scratch-induced lesions with elevated borders and central necrosis. This so-called umbilicated type of prurigo (UP) is rare and is assumed to develop preferentially in the context of metabolic diseases. The aim of this study was to characterize UP in its clinical and histological dimension. Demographic and clinical data were collected from 23 patients with UP. Intensive light microscopical analysis of biopsied lesions was performed. Statistical comparison with previous results for prurigo nodularis (PN) showed that UP is clearly a subtype of PN. In addition, clinical and microscopic features of epidermal perforation identical to those in acquired reactive perforating dermatosis (ARDP) were observed. Hence, we suggest that ARDP is identical to UP and is therefore a subtype of PN. We assume that reduced wound healing capacities due to underlying systemic disorders, particularly diabetes mellitus and uraemia, underlie the pathomechanism of development of umbilicated skin lesions with a perforating aspect.