Warty papule and scaling around finger
Attempts at removing the erythematous papule using cryotherapy had failed. A biopsy confirmed our suspicions.
Differential includes onychomycosis, eczema
The differential for BD of the nail includes onychomycosis, paronychia, verruca vulgaris, eczema, pyogenic granuloma, glomus tumor, and verrucous tuberculosis. The differential also includes: subungual exostosis, onychomatricoma, amelanotic malignant melanoma, keratoacanthoma, fibrokeratoma, and gouty tophus.
Irregular borders and the presence of a scaly patch with papules should raise your suspicion of BD. Biopsy is necessary to confirm your suspicions. In fact, all chronic and recalcitrant lesions of the nail apparatus should be biopsied to rule out BD.9
Biopsy with care
The matrix is a germinating portion of the nail and requires special care, because damage to it may permanently affect nail formation and function. Proper anesthesia and hemostasis are also key, given that the nail apparatus is very vascular and well innervated.9
The histopathology of BD lesions is characterized by hyperkeratosis; parakeratosis; loss of orderly maturation, polarity, and a granular layer; and keratinocytic atypia involving the entire acanthotic epithelial layer. The atypia and dyskeratosis are confined to the epidermis. However, some microscopic specimens of BD may simultaneously demonstrate features of invasive SCC in other areas of the lesion. Microinvasion is common in long-term BD with reports of invasive carcinoma in approximately 15% of cases.4-6,9
