What to Know about Melanonychia

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This post was written with Consensus AI Academic Search Engine – please read our Disclaimer at the end of this article. Melanonychia is a complex condition with a wide range of causes. Accurate diagnosis and appropriate management are crucial to prevent misdiagnosis and ensure effective treatment. Clinicians should be aware of the various etiologies and use a systematic approach to evaluate and manage this condition.

Melanonychia refers to the brown or black pigmentation of the nail plate, which can be caused by a variety of factors. This condition can be a diagnostic challenge for clinicians due to its diverse etiologies, ranging from benign to malignant causes. Understanding the underlying causes, diagnostic methods, and treatment options is crucial for effective management.

Causes of Melanonychia

Melanonychia can be caused by both exogenous and endogenous factors. Exogenous sources include bacterial or fungal infections, tar, or blood. Endogenous causes are often related to melanin production in the nail bed, which can result from melanocytic activation or hyperplasia.

Fungal Melanonychia

Fungal melanonychia is a relatively rare condition caused by nail infections that produce brown-to-black pigmentation. Over 21 species of dematiaceous fungi and at least 8 species of nondematiaceous fungi have been implicated as etiologic agents. Common fungi include Candida and Aspergillus species. These infections can mimic subungual melanoma and are often resistant to traditional antifungal therapies .

Melanocytic Lesions

Melanonychia can also result from melanocytic lesions, which may be benign or malignant. Benign causes include nail matrix melanocytic activation and hyperplasia, while malignant causes include melanoma. In children, benign melanocytic hyperplasia such as lentigo or nevus is a common cause .

Drug-Induced Melanonychia

Certain medications can induce melanonychia, affecting multiple nails and presenting as light brown to black pigmentation. Chemotherapeutic agents like azathioprine, bleomycin sulfate, and methotrexate are commonly associated with this condition. A case of melanonychia induced by the traditional Chinese herb Citri reticulatae pericarpium has also been reported.

Diagnostic Methods

Accurate diagnosis of melanonychia is essential to differentiate between benign and malignant causes. Diagnostic tools include dermoscopy, biopsy, and histopathologic examination .

Dermoscopy

Dermoscopy is routinely used to evaluate pigmented nails. It helps identify whether the pigmentation is due to melanocytic activation or proliferation.

Biopsy and Histopathology

When melanocytic proliferation is suspected, a biopsy followed by histopathologic examination is the gold standard for diagnosis. This is particularly recommended for longitudinal melanonychia in adults localized to a single digit. Histopathologic features such as melanocyte counts and the presence of suprabasal melanocytes are crucial for diagnosis.

Management and Treatment

The management of melanonychia depends on the underlying cause.

Malignant Lesions

Malignant lesions, such as melanoma, require excisional biopsy and appropriate oncologic treatment .

Fungal Infections

Fungal melanonychia should be treated with antifungal agents. However, these infections can be persistent and may recur after treatment cessation.

Benign Lesions

Benign lesions and hyperpigmentation may be managed conservatively with a wait-and-see approach. Regular monitoring is essential to detect any changes that may indicate malignancy .

 


Disclaimer

The content presented in this blog is generated by Consensus, an AI-powered academic search engine, and is based on publicly available scientific literature. While every effort is made to provide accurate, up-to-date, and well-researched information, the content is intended for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before making any decisions regarding medical conditions, treatments, or medications. The AI system’s analysis may not cover all perspectives, emerging research, or individual cases, and it is not a substitute for professional expertise. Neither the blog publisher nor the developers of the AI-powered search engine are responsible for any actions taken based on the information provided in this content. Use of this information is at your own risk. Citations to the original scientific studies are included for reference, but these studies should be reviewed in full and interpreted with the guidance of a healthcare or research professional.

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