A Case of Pigmented Bowen's Disease of the Penis with Caracteristic Regular Blue-gray Globules on Dermoscopy

Abstract

A 37-year-old man presented with a gray to black pigmented macule on the penis that had been present for three years. The clinical examination showed a gray to black pigmented, slightly elevated and soft macule of 11×6 mm in diameter at his first visit to our hospital. A dermoscopic examination revealed gray to brown homogeneous pigmentation and blue-white structures. The peripheral area of the macule demonstrated small blue-gray globules. A biopsy was taken, and the pathological examination revealed atypical keratinocytes showing hyperchromatic nuclei and mitosis by hematoxylin-eosin staining. A diagnosis of pigmented Bowen's disease was established based on pathological and clinical observations. It is generally difficult to differentiate a pigmented macule on the penis from superficial spreading melanoma. We excluded melanoma because we did not recognize structures suggestive of melanoma, such as atypical pigment network, irregular streaks or irregular dots/globules. Additionally, an observation of regular small blue-gray globules might be suggestive of pigmented Bowen's disease. In conclusion, we learned that dermoscopy might be useful for establishing a diagnosis of pigmented Bowen's disease of the penis.