Dermoscopy of pyogenic granuloma: a morphological study

Abstract

Background: Pyogenic granuloma is a common, benign, vascular lesion of the skin and mucous membranes which is a simulator of amelanotic/hypomelanotic melanoma and other tumours. Objectives: To determine the diagnostic significance of dermoscopic structures and patterns associated with pyogenic granulomas in a large series of cases. Methods: Digital dermoscopic images of histopathologically proven cases of 122 pyogenic granulomas and 140 other tumours (28 amelanotic melanomas, seven melanoma metastases, 22 basal cell carcinomas and 83 other tumours) were collected from university hospitals in Spain, Italy, Austria and Turkey. The frequency, sensitivity, specificity, positive predictive value, negative predictive value, intraobserver agreement and interobserver agreement of the dermoscopic structures and patterns associated with pyogenic granulomas were calculated. Results: Vascular structures were observed in 45% of pyogenic granulomas (sensitivity of 45·1% and specificity of 17·9%; both P < 0·001). Seven exclusive patterns were made up from the combination of the structures 'reddish homogeneous area' (RHA), 'white collarette' (WC), 'white rail lines' (WRL) and 'vascular structures' (VS). The pattern composed of RHA, WC and WRL showed the highest sensitivity (22·1%; P < 0·001) and a specificity of 100% (P < 0·001) for pyogenic granulomas. Two other patterns (RHA + WC and RHA + WC + WRL + VS) showed 100% specificity when compared with melanoma (P < 0·001 and P < 0·05, respectively). Conclusions: Even though some dermoscopic patterns are useful in the recognition of pyogenic granulomas, dermoscopy is not a substitute for histology, mostly when vessels are present, as melanoma cannot be ruled out.