What is the diagnosis and treatment for a 65-year-old male with pruritic (itchy) fissures on the soles of both feet and rashes, possibly tinea (fungal infection), on the entire body, worse on the back, chest, and abdomen?

Diagnosis and Treatment of Widespread Dermatophyte Infection with Plantar Fissures

Diagnosis

This clinical presentation is most consistent with extensive tinea corporis with tinea pedis (moccasin-type), confirmed by potassium hydroxide (KOH) microscopy and fungal culture of skin scrapings. 1

Key Diagnostic Features

• Bilateral plantar fissures that are pruritic but not painful strongly suggest chronic hyperkeratotic (moccasin-type) tinea pedis, which characteristically involves the soles, heels, and sides of the feet 2
• Widespread body rash worse on trunk indicates tinea corporis, likely representing disseminated dermatophyte infection 3, 4
• The combination of extensive body involvement with plantar disease suggests Trichophyton rubrum as the most likely causative organism, as this dermatophyte commonly causes both tinea corporis and chronic plantar tinea pedis 2

Essential Diagnostic Confirmation

• Obtain skin scrapings from the active border of lesions on both the trunk and feet for KOH wet-mount examination as point-of-care testing 2
• Microscopic examination following digestion with 10% potassium hydroxide can confirm the presence of dermatophytes 1
• Fungal culture on Sabouraud's agar should be performed to identify the specific dermatophyte species and guide therapy, particularly given the extensive nature of infection 4

Treatment Approach

Given the extensive body surface area involvement and chronic plantar fissuring, systemic oral antifungal therapy is required rather than topical treatment alone. 2, 5

Primary Systemic Treatment

Terbinafine 250 mg orally once daily is the first-line systemic therapy, as it demonstrates superior efficacy compared to griseofulvin (RR 2.26,95% CI 1.49-3.44) and proven effectiveness versus placebo (RR 24.54,95% CI 1.57-384.32) 5

• Duration: 2 weeks for tinea corporis on the trunk 3
• Duration: 4 weeks for moccasin-type tinea pedis with plantar involvement 3, 2
• Continue treatment for at least 1 week after clinical clearing to prevent recurrence 3

Alternative Systemic Options

If terbinafine is contraindicated or not tolerated:

• Itraconazole has demonstrated effectiveness versus placebo (RR 6.67,95% CI 2.17-20.48) 5
• Fluconazole 150-200 mg once daily can be used, though evidence is less robust than for terbinafine 6, 5

Essential Adjunctive Topical Therapy

Add topical terbinafine 1% cream twice daily for 1 week to address bacterial overgrowth in macerated plantar fissures, as macerated ulcers are particularly associated with Pseudomonas aeruginosa in wet, macerated athlete's foot 7

Critical Adjunctive Measures

• Apply foot powder after bathing to reduce recurrence from 8.5% to 2.1% 7
• Treat any concomitant onychomycosis, as nail infection serves as a reservoir for reinfection and may explain the extensive body involvement 1, 7
• Maintain good personal hygiene: keep skin dry and cool, avoid sharing towels or clothing 4

Management of Plantar Fissures

For the pruritic plantar fissures specifically:

• Topical propylene glycol 50% in water for 30 minutes under plastic occlusion nightly, followed by hydrocolloid dressing application 1
• Urea- or polidocanol-containing lotions to soothe pruritus 1
• Oral H1-antihistamines (cetirizine, loratadine, or fexofenadine) if pruritus is severe 1

Critical Pitfalls to Avoid

• Do not rely on topical therapy alone for extensive disease covering large body surface areas, as this will likely fail 3, 2
• Do not overlook Gram-negative organisms (particularly Pseudomonas) in severe macerated plantar cases, which may require broader antimicrobial coverage 7
• In diabetic patients, pay particular attention to macerated interdigital spaces and fissures, as these serve as portals for streptococcal cellulitis and limb-threatening complications 1, 7
• Do not stop treatment prematurely when clinical improvement occurs; inadequate treatment duration leads to recurrence of active infection 6

Follow-Up and Monitoring

• Reassess after 2 weeks of systemic therapy to evaluate response 1
• Obtain post-treatment skin scrapings to ensure mycological clearance 1
• Monitor for 6 months after treatment completion to detect recurrence 5
• Most common adverse effects are gastrointestinal with all oral antifungals; monitor for these during treatment 5