Onychomycosis: Clinical Presentation, Diagnostic Evaluation, Antifungal Management, and Outcomes – A Case Report

Abstract

Onychomycosis is a common fungal infection of the nails caused primarily by dermatophytes, yeasts, and non-dermatophyte molds. It accounts for approximately 50% of all nail disorders and significantly affects quality of life due to cosmetic concerns, discomfort, and functional impairment. The condition commonly presents with nail discoloration, thickening, brittleness, subungual debris, and progressive nail destruction.

Accurate diagnosis requires careful clinical examination supported by laboratory confirmation through microscopy, fungal culture, or molecular techniques. Early diagnosis and appropriate antifungal therapy are essential to prevent disease progression and recurrence.

We present the case of a 52-year-old male who presented with progressive discoloration and thickening of the toenails associated with difficulty trimming the nails and discomfort while walking. Clinical examination, potassium hydroxide (KOH) microscopy, and fungal culture confirmed distal lateral subungual onychomycosis caused by Trichophyton rubrum. The patient was successfully treated with oral terbinafine and supportive nail care, resulting in significant clinical improvement and healthy nail regrowth.

This case highlights the importance of early recognition, laboratory confirmation, and comprehensive treatment strategies in achieving favorable outcomes in patients with onychomycosis.

Introduction

Onychomycosis refers to a fungal infection affecting the nail unit, including the nail plate, nail bed, and surrounding tissues. It is one of the most common nail disorders encountered in dermatological practice and represents a substantial healthcare burden worldwide.

The condition is predominantly caused by dermatophytes, particularly Trichophyton rubrum and Trichophyton interdigitale, although yeasts such as Candida species and non-dermatophyte molds may also be responsible.

Common risk factors for onychomycosis include:

• Advanced age
• Diabetes mellitus
• Peripheral vascular disease
• Immunosuppression
• Repeated nail trauma
• Hyperhidrosis
• Tinea pedis
• Use of occlusive footwear

The infection may lead to progressive nail dystrophy, discomfort, secondary bacterial infections, and psychosocial distress. Prompt diagnosis and treatment are therefore essential.

Case Report

Patient History

A 52-year-old male presented to the dermatology outpatient department with complaints of:

• Progressive yellow discoloration of the right great toenail for 12 months
• Thickening of the affected nail
• Difficulty trimming the nail
• Mild discomfort while walking
• Cosmetic concerns regarding nail appearance

The patient reported gradual progression of symptoms over the preceding year. There was no history of acute trauma or significant pain.

Additional history revealed:

• Long-standing tinea pedis for several years
• Excessive sweating of the feet
• Frequent use of closed footwear during work

Past medical history included:

• Type 2 diabetes mellitus for 8 years
• Hypertension controlled with medication

There was no history of:

• Psoriasis
• Recent nail surgery
• Immunosuppressive therapy
• Peripheral neuropathy

Clinical Examination

General Examination

• Blood pressure: 130/82 mmHg
• Pulse rate: 78/min
• Temperature: Afebrile
• General condition: Stable

Dermatological Examination

Inspection revealed:

• Yellow-brown discoloration of the right great toenail
• Marked nail plate thickening
• Subungual hyperkeratosis
• Distal nail separation from the nail bed (onycholysis)

The nail surface appeared rough and brittle.

Associated findings included:

• Interdigital scaling between the toes
• Mild plantar erythema consistent with tinea pedis

No evidence of surrounding cellulitis or secondary bacterial infection was observed.

Clinical Evaluation

Differential Diagnosis

The following conditions were considered:

• Onychomycosis
• Nail psoriasis
• Traumatic nail dystrophy
• Lichen planus involving nails
• Chronic paronychia

The presence of subungual hyperkeratosis, nail discoloration, and concurrent tinea pedis strongly suggested fungal nail infection.

Investigations

Laboratory Evaluation

Routine investigations demonstrated:

• Hemoglobin: 13.6 g/dL
• Total leukocyte count: 7,800/mm³
• Blood glucose: Mildly elevated
• Renal function tests: Normal
• Liver function tests: Normal

Dermoscopy

Onychoscopy demonstrated:

• Jagged proximal border of onycholysis
• Longitudinal streaks
• Subungual debris

These findings further supported the diagnosis of onychomycosis.

Potassium Hydroxide (KOH) Microscopy

Nail scrapings were obtained from the affected area.

Microscopic examination demonstrated:

• Septate fungal hyphae
• Positive findings consistent with dermatophyte infection

Fungal Culture

Culture of nail samples revealed:

• Growth of Trichophyton rubrum

Diagnosis

Based on clinical examination, microscopy, and fungal culture, a diagnosis of:

Distal Lateral Subungual Onychomycosis Caused by Trichophyton rubrum

was established.

Management and Outcome

Initial Management

The patient was counseled regarding the chronic nature of the disease and the importance of treatment adherence.

Treatment included:

• Oral terbinafine 250 mg once daily
• Mechanical nail trimming and debridement
• Treatment of concurrent tinea pedis
• Advice regarding foot hygiene

Additional recommendations included:

• Keeping feet dry
• Regular sock changes
• Avoidance of sharing footwear
• Use of antifungal powders

Follow-Up and Clinical Course

At 6 Weeks

• Reduced nail discoloration progression
• Improvement in surrounding skin lesions
• Good treatment adherence

At 3 Months

• Significant reduction in subungual debris
• Healthier proximal nail growth observed
• No adverse drug reactions

At 6 Months

• Marked improvement in nail appearance
• Resolution of discomfort during walking
• Nearly complete replacement of diseased nail

At 9 Months

• Complete clinical recovery
• Healthy nail plate regrowth
• No evidence of recurrence

Discussion

Pathophysiology

Onychomycosis develops when fungal organisms invade the nail unit and establish persistent infection. Dermatophytes possess keratinolytic enzymes that facilitate penetration and colonization of keratinized structures.

Several factors contribute to disease development:

• Warm and moist environments
• Repeated microtrauma
• Reduced peripheral circulation
• Impaired immune function
• Presence of tinea pedis

The infection commonly begins at the distal nail edge and gradually progresses proximally.

Epidemiology

Important epidemiological features include:

• Onychomycosis affects approximately 5–15% of the global population
• Prevalence increases with age
• Men are affected more frequently than women
• Diabetes significantly increases susceptibility
• Toenails are affected more commonly than fingernails

Dermatophytes remain the leading causative organisms worldwide.

Clinical Manifestations

Patients with onychomycosis commonly present with:

• Nail discoloration
• Thickened nails
• Brittle nail texture
• Subungual debris
• Nail plate distortion
• Difficulty cutting nails

Advanced disease may result in:

• Pain during walking
• Secondary bacterial infection
• Functional impairment
• Psychosocial distress

Diagnostic Considerations

Diagnosis is based on:

1. Clinical history
2. Physical examination
3. KOH microscopy
4. Fungal culture
5. Histopathological examination when necessary
6. Molecular diagnostic techniques in selected cases

Laboratory confirmation is important because several nail disorders can mimic fungal infection.

Treatment Modalities

Topical Therapy

Suitable for mild disease:

• Ciclopirox nail lacquer
• Efinaconazole solution
• Tavaborole solution

Systemic Therapy

Oral antifungal agents remain the gold standard for extensive disease.

Common medications include:

• Terbinafine
• Itraconazole
• Fluconazole

Terbinafine is generally preferred due to high cure rates and favorable safety profile.

Adjunctive Measures

Supportive management includes:

• Nail debridement
• Foot hygiene optimization
• Treatment of tinea pedis
• Preventive education

Complications

Potential complications include:

• Permanent nail dystrophy
• Secondary bacterial infection
• Pain and mobility limitation
• Recurrent infection
• Spread to adjacent nails

Early treatment significantly reduces these complications.

Prognosis

The prognosis depends on:

• Extent of nail involvement
• Causative organism
• Presence of comorbidities
• Treatment adherence
• Duration of infection

Patients receiving appropriate antifungal therapy generally experience excellent outcomes, although recurrence remains possible.

Conclusion

Onychomycosis is a common fungal nail infection that can significantly impact physical comfort, nail function, and quality of life. Careful clinical assessment combined with laboratory confirmation is essential for establishing an accurate diagnosis and guiding appropriate therapy. This case demonstrates the successful management of distal lateral subungual onychomycosis caused by Trichophyton rubrum through oral antifungal treatment, nail care, and preventive measures. Early diagnosis, patient education, and adherence to therapy remain critical for achieving favorable outcomes and minimizing recurrence.

References

1. Lipner SR, Scher RK. Onychomycosis: Clinical overview and diagnosis. J Am Acad Dermatol. 2019;80(4):835–851. https://pubmed.ncbi.nlm.nih.gov/30691753/
2. Gupta AK, Versteeg SG. Onychomycosis therapy: Past, present, future. J Fungi. 2017;3(4):56. https://pmc.ncbi.nlm.nih.gov/articles/PMC5770011/
3. Piraccini BM, Alessandrini A. Onychomycosis: A review. J Fungi. 2015;1(1):30–43. https://pmc.ncbi.nlm.nih.gov/articles/PMC5770012/
4. Westerberg DP, Voyack MJ. Onychomycosis: Current trends in diagnosis and treatment. Am Fam Physician. 2013;88(11):762–770. https://pubmed.ncbi.nlm.nih.gov/24364524/
5. Gupta AK, Mays RR. The impact of onychomycosis on quality of life. Skin Appendage Disord. 2018;4(4):208–216. https://pmc.ncbi.nlm.nih.gov/articles/PMC6249733/
6. Scher RK, Tavakkol A, Sigurgeirsson B, et al. Onychomycosis: Diagnosis and definition of cure. J Am Acad Dermatol. 2007;56(6):939–944. https://pubmed.ncbi.nlm.nih.gov/17504709/
7. Elewski BE, Rich P, Pollak R, et al. Efinaconazole topical solution for onychomycosis. J Drugs Dermatol. 2013;12(2):186–192. https://pubmed.ncbi.nlm.nih.gov/23377374/
8. Ameen M, Lear JT, Madan V, et al. British Association of Dermatologists’ guidelines for management of onychomycosis. Br J Dermatol. 2014;171(5):937–958. https://pubmed.ncbi.nlm.nih.gov/25209742/
9. Leung AKC, Lam JM, Leong KF, et al. Onychomycosis: An updated review. Recent Pat Inflamm Allergy Drug Discov. 2020;14(1):32–45. https://pubmed.ncbi.nlm.nih.gov/31663326/
10. Gupta AK, Foley KA. Evidence-based management of onychomycosis. Am J Clin Dermatol. 2019;20(6):839–851. https://pubmed.ncbi.nlm.nih.gov/31468220/

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