Onychomycosis Endonyx: A Systematic Review.

Area of Science:

• Dermatology
• Mycology
• Infectious Diseases

Background:

• Endonyx onychomycosis is a chronic nail infection characterized by milky white discoloration without hyperkeratosis or onycholysis.
• Initially attributed to *T. soudanense* and *T. violaceum*, its understanding has evolved.

Purpose of the Study:

• To systematically review and analyze the definitions and clinical characteristics of endonyx onychomycosis cases reported in the literature.
• To assess the consistency of diagnostic criteria used in published studies.

Main Methods:

• A systematic literature review was conducted using terms "endonyx" AND "onychomycosis" across major scientific databases (PubMed, SciELO, SCOPUS, Web of Science, Google Scholar).
• Analysis focused on definitions, clinical presentations, and etiological agents in reported cases.

Main Results:

• A total of 175 patients from 28 articles were identified, predominantly from Asia and Africa.
• Significant heterogeneity in diagnostic criteria was observed, with only 47.3% aligning with the original description; another 47.3% lacked traceable diagnostic criteria.
• Identified etiological agents included *Trichophyton soudanense*, *T. rubrum*, *T. violaceum*, *T. tonsurans*, and *Fusarium* spp., with most studies lacking specific insights into the endonyx variant.

Conclusions:

• There is a critical need for standardized clinical descriptions and histopathological analyses to accurately identify causative fungi, including less common ones.
• Development of precise diagnostic and treatment protocols for endonyx onychomycosis is essential.