Molecularly confirmed neoscytalidium dimidiatum onychomycosis in an immunocompetent Iranian woman: a case report and comprehensive literature review
5 affiliations
- 1Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- 2Department of Parasitology and Mycology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
- 3Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- 4Department of Molecular and Cellular Biology, Zand Institute of Higher Education, Shiraz, Iran
- 5Department of Medical Parasitology and Mycology, Faculty of Medicine, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
Abstract
Background: Onychomycosis is one of the most common fungal infections of the nails and is predominantly caused by dermatophytes. However, non-dermatophyte molds (NDMs), including dematiaceous fungi, are increasingly recognized as clinically relevant pathogens. Neoscytalidium dimidiatum is an uncommon cause of onychomycosis, reported predominantly in tropical and subtropical regions, although cases from temperate settings have also been described.
Case presentation: We report a case of distal and lateral subungual onychomycosis (DLSO) caused by N. dimidiatum in a 54-year-old immunocompetent Iranian woman without underlying systemic disease or immunosuppressive therapy. She presented with progressive discoloration and dystrophic changes of a toenail following previous trauma. Direct microscopy of nail specimens using potassium hydroxide (KOH) demonstrated septate, branching fungal hyphae with occasional pigmentation. Culture on Sabouraud dextrose agar yielded a rapidly growing melanized-mold with characteristic dark pigmentation. Given the phenotypic overlap among Neoscytalidium species, molecular identification was performed. Internal transcribed spacer (ITS) rDNA sequencing identified the isolate as N. dimidiatum, with more than 99% sequence identity to reference sequences. The patient received combination therapy with oral itraconazole, amorolfine 5% nail lacquer, and topical sertaconazole 2%, with marked clinical improvement after 3 months; mycological cure remained under evaluation.
Conclusion: This case contributes to the limited literature on N. dimidiatum onychomycosis by documenting molecularly confirmed DLSO in an immunocompetent Iranian woman and demonstrating concordant clinical, mycological, and molecular findings. It highlights the diagnostic challenges of NDM onychomycosis and supports an integrated approach combining direct microscopy, culture, and molecular identification for accurate species-level diagnosis and appropriate clinical management.
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BibTeX
@article{haghighat2026molecularly,
title = {{Molecularly confirmed neoscytalidium dimidiatum onychomycosis in an immunocompetent Iranian woman: a case report and comprehensive literature review}},
author = {Fuad Haghighat and Seyed Jamal Hashemi and Shahram Mahmoudi and Abbas Rahimi Foroushani and Kimia Kamali Sarvestani and Mohsen Gerami Shoar and Roshanak Daie Ghazvini and Leila Hossein pour and Mahsa Naeimi Eshkaleti and Hasti Kamali Sarvestani},
journal = {IDCases},
year = {2026},
month = oct,
doi = {10.1016/j.idcr.2026.e02812},
url = {https://doi.org/10.1016/j.idcr.2026.e02812},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Molecularly confirmed neoscytalidium dimidiatum onychomycosis in an immunocompetent Iranian woman: a case report and comprehensive literature review
AU - Fuad Haghighat
AU - Seyed Jamal Hashemi
AU - Shahram Mahmoudi
AU - Abbas Rahimi Foroushani
AU - Kimia Kamali Sarvestani
AU - Mohsen Gerami Shoar
AU - Roshanak Daie Ghazvini
AU - Leila Hossein pour
AU - Mahsa Naeimi Eshkaleti
AU - Hasti Kamali Sarvestani
PY - 2026
DA - 2026/10/22
JO - IDCases
DO - 10.1016/j.idcr.2026.e02812
UR - https://doi.org/10.1016/j.idcr.2026.e02812
AB - Background: Onychomycosis is one of the most common fungal infections of the nails and is predominantly caused by dermatophytes. However, non-dermatophyte molds (NDMs), including dematiaceous fungi, are increasingly recognized as clinically relevant pathogens. Neoscytalidium dimidiatum is an uncommon cause of onychomycosis, reported predominantly in tropical and subtropical regions, although cases from temperate settings have also been described. Case presentation: We report a case of distal and lateral subungual onychomycosis (DLSO) caused by N. dimidiatum in a 54-year-old immunocompetent Iranian woman without underlying systemic disease or immunosuppressive therapy. She presented with progressive discoloration and dystrophic changes of a toenail following previous trauma. Direct microscopy of nail specimens using potassium hydroxide (KOH) demonstrated septate, branching fungal hyphae with occasional pigmentation. Culture on Sabouraud dextrose agar yielded a rapidly growing melanized-mold with characteristic dark pigmentation. Given the phenotypic overlap among Neoscytalidium species, molecular identification was performed. Internal transcribed spacer (ITS) rDNA sequencing identified the isolate as N. dimidiatum, with more than 99% sequence identity to reference sequences. The patient received combination therapy with oral itraconazole, amorolfine 5% nail lacquer, and topical sertaconazole 2%, with marked clinical improvement after 3 months; mycological cure remained under evaluation. Conclusion: This case contributes to the limited literature on N. dimidiatum onychomycosis by documenting molecularly confirmed DLSO in an immunocompetent Iranian woman and demonstrating concordant clinical, mycological, and molecular findings. It highlights the diagnostic challenges of NDM onychomycosis and supports an integrated approach combining direct microscopy, culture, and molecular identification for accurate species-level diagnosis and appropriate clinical management.
SN - 2214-2509
ER -