[Dark nail: clinical findings, diagnostics and therapy of melanonychia]

BACKGROUND

A dark colored pigmentation of nails can be due to a subungual malignant melanoma. There are, however, many other benign causes and this differentiation is an important challenge in dermatological practice.

PROBLEM

When should nail pigmentation be clarified by histological investigations?

MATERIAL AND METHODS

This article gives a survey of the literature on this topic and a review of own experiences with clinical case examples. The various causes of melanonychia are presented and criteria for the early recognition of melanoma of the nail matrix are formulated.

RESULTS

The width and depth of color of longitudinal melanonychia do not allow any conclusions on the dignity. If the nail striation is proximally broader than distally, this is evidence of a proliferative event. Confirmation of a subungual hemorrhage does not exclude a malignancy per se. Also detection of pigmentation due to fungi does not exclude the additional presence of a subungual melanoma. A systematic clinical analysis using clear criteria leads to a working diagnosis and suitable treatment.

CONCLUSION

An early and correct designation of nail pigmentation can avoid unnecessary nail interventions but can also be life saving.

Melanonychia

Melanonychia, or melanin-derived brown-to-black nail pigmentation, is a diagnostic challenge for clinicians. The most serious disease of the nail unit, melanoma, primarily presents with melanonychia. However, melanonychia most often occurs as a result of benign etiologies such as nail matrix melanocytic activation, nail matrix melanocytic hyperplasia, and nail invasion by melanin-producing pathogens. Regrettably, patients with nail apparatus melanoma are often initially misdiagnosed, and due to diagnostic delays of an average of 2 years, melanoma of the nail unit carries a poor prognosis. Having a thorough knowledge of the various causes of melanonychia and using a systematic approach when evaluating brown-to-black nail pigmentation may help prevent misdiagnosis and thereby improve prognosis.

Phaeohyphomycosis and onychomycosis due to Chaetomium spp., including the first report of Chaetomium brasiliense infection

Chaetomium species have been rarely described as aetiological agents of invasive and dermatomycotic infections in humans. The majority of cases have been reported within the last two decades. Treatment failed in most of these cases. In this paper we present two cases in which Chaetomium spp. can be clearly identified as an aetiological agent in pathological conditions. In the first report, we describe a new aetiological agent, Chaetomium brasiliense, which was implicated in a case of otitis externa in a patient with spinocellular carcinoma basis cranii. The patient had been repeatedly treated for relapsing otitis externa and had previously undergone surgery several times for otitis media. The fungal aetiology was confirmed by repeated positive culture and histologic studies. The second case involved onychomycosis with strikingly brown nail discoloration due to Chaetomium globosum in an otherwise healthy patient. The nail lesion was successfully cured by oral terbinafine. The determination of both species was supported by sequencing of rDNA regions. The morphological aspect of Chaetomium spp. identification is also discussed. In vitro antifungal susceptibility tests demonstrated that both isolates were susceptible to terbinafine and azole derivates except fluconazole. Amphotericin B was effective only against the C. brasiliense strain. We review the literature to summarize clinical presentations, histologic findings, and treatment strategies.

Nail surgery: practical tips and treatment options

This paper provides an introductory overview of nail surgery, including basic principles, anesthesia, wound dressings, and several common nail procedures. In detail, it reviews how to achieve complete anesthesia and hemostasis, perform matrix injection, punch biopsy of the plate, bed, and matrix, and nail fold biopsy, with practical tips and suggested surgical indications.

Pigmented nail disorders

Nail pigmentation is defined by the presence of melanin in the nail plate. It most frequently has the appearance of a longitudinal pigmented band, called longitudinal mel-anonychia (LM). LM is an important aspect of ungual pathology because it can be the first sign of nail apparatus melanoma. The aim of this article is to help distinguish those types of melanonychia that are worrisome and should lead to biopsy from those that are reasonably reassuring and need only be followed clinically. Histology, differential diagnosis, and biopsy techniques also are considered.

A case of melanonychia due to Candida albicans

Candida species rarely cause black pigmentation of infected nails and only a few cases have been reported in the literature. We describe a 53-year-old white man who had diffuse melanonychia of the fourth right fingernail due to C. albicans. A progressive dark pigmentation of his nail appeared over 6 months, following paronychial inflammation. The melanonychia was associated with brittleness. There was no onycholysis or hyperkeratosis. Direct examination with potassium hydroxide demonstrated round yeast cells in the specimen. The samples were cultured on Sabouraud glucose agar containing chloramphenicol at 27 degrees C and showed white growth after a few days. The patient was successfully treated with systemic itraconazole.

Pigmentary disorders in ethnic skin

Pigmentary disorders are commonly seen in ethnic skin. They are psychologically problematic in darker skin. Treatment of many of these disorders remains difficult.