Dermoscopy of nail pigmentations
- Antonella Tosti, MD
Antonella Tosti, MD
- Professor of Clinical Dermatology
- Department of Dermatology and Cutaneous Surgery, Miller School of Medicine, University of Miami
Nail pigmentation is most commonly caused by deposits of melanin or hemosiderin within the nail plate. It is rarely due to deposits of other pigments of endogenous or exogenous origin.
Melanin deposits result from activation or proliferation of nail matrix melanocytes and in most cases present as a longitudinal pigmented band called longitudinal melanonychia or melanonychia striata .
Nail dermoscopy (onychoscopy) can greatly improve the differential diagnosis of nail pigmentation and helps clinicians with at least minimal training in dermoscopy to distinguish benign lesions, which do not require additional examinations, from lesions that require excision for pathologic evaluation or regular follow-up [2,3].
However, dermoscopy should not be considered a substitute for pathology in the differential diagnosis of doubtful cases of longitudinal melanonychia . This topic will discuss the causes of nail pigmentation and the dermoscopic evaluation of benign and malignant pigmented nail lesions. Nail disorders are discussed separately. The dermoscopic evaluation of cutaneous and mucosal lesions is also discussed separately. Dermoscopic algorithms for skin cancer triage are also discussed separately.
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- ANATOMY OF THE NAIL AND DISTRIBUTION OF NAIL MELANOCYTES
- CAUSES OF NAIL PIGMENTATION
- Nail pigmentation due to melanin deposition
- Nail pigmentation due to blood deposition
- EXAMINATION OF NAIL AND PERIUNGUAL TISSUES
- Types of dermatoscopes
- Limitations of nail dermoscopy
- DERMOSCOPIC PATTERNS OF NAIL PLATE PIGMENTATION
- Background color
- Arrangement of lines within brown/black bands
- Homogeneous black pigmentation
- Dots and globules
- Blood spots
- DERMOSCOPY OF NAIL PLATE FREE EDGE
- DERMOSCOPY OF PROXIMAL NAIL FOLD
- DERMOSCOPY OF THE HYPONYCHIUM
- INTRAOPERATIVE DERMOSCOPY OF THE NAIL MATRIX
- DIFFERENTIAL DIAGNOSIS OF NAIL PIGMENTATIONS
- Benign lesions
- - Ethnic-type melanonychia
- - Traumatic melanonychia
- - Drug-induced melanonychia
- - Postinflammatory melanonychia
- - Fungal melanonychia
- - Nevi
- - Lentigo
- - Onychopapilloma
- - Hematoma
- Malignant lesions
- - Melanoma
- - Bowen disease/squamous cell carcinoma
- MELANONYCHIA IN CHILDREN
- SUMMARY AND RECOMMENDATIONS