What is the diagnosis and treatment for an adult patient presenting with skin-colored verrucous papules and plaques on the groin?

Diagnosis and Treatment of Skin-Colored Verrucous Papules and Plaques on the Groin

The most likely diagnosis is tinea cruris (jock itch), and first-line treatment is topical terbinafine 1% cream applied daily for 1 week, which achieves a 94% mycological cure rate. 1

Differential Diagnosis

The presentation of skin-colored verrucous papules and plaques in the groin requires consideration of several entities:

Most Common: Dermatophyte Infection (Tinea Cruris)

• Tinea cruris typically presents as annular, scaly plaques with raised borders in the groin folds 1
• The verrucous appearance may represent a more chronic or severe infection 2
• Risk factors include lack of circumcision (for genital involvement), moisture, and occlusion 1
• Perform KOH preparation of skin scrapings to identify septate hyphae before initiating treatment 3

Important Alternative: Granular Parakeratosis

• Verrucous granular parakeratosis presents as erythematous scaly papules and plaques in intertriginous areas including the groin 4
• Histopathology shows compact hyperkeratosis with basophilic granules and psoriasiform hyperplasia 4
• This diagnosis requires skin biopsy for confirmation 4

Less Common Considerations

• Erdheim-Chester disease can manifest as yellowish-brown papules or plaques in skin folds including the groin 1
• Invasive dermatophytosis may present with verrucous papules and nodules in immunocompromised patients, though this patient had lymphadenopathy 2
• HPV-related lesions in immunocompromised patients can present as verrucous papules 5

Diagnostic Workup

The essential initial workup includes: 3

• KOH preparation and microscopic examination of skin scrapings to identify fungal elements 3
• Wood's lamp examination to exclude erythrasma (coral-red fluorescence) 3, 6
• Fungal culture if KOH is positive to identify the specific organism 3

Biopsy is indicated if: 4

• Lesions fail to respond to appropriate antifungal therapy after 2-4 weeks
• Clinical appearance is atypical for dermatophyte infection
• Patient is immunocompromised 5

Treatment Algorithm

For Confirmed Tinea Cruris:

First-line therapy: 1

• Terbinafine 1% cream applied once daily for 1 week (94% mycological cure rate, approved for ages 12 and older) 1

Alternative topical options: 1

• Butenafine applied twice daily for 2 weeks (over-the-counter, adults only) 1
• Clotrimazole applied twice daily for 4 weeks 1

For extensive or refractory disease: 1

• Oral itraconazole 100 mg daily for 2 weeks or 200 mg daily for 1 week (superior to oral griseofulvin) 1
• Oral terbinafine 250 mg daily for 2 weeks 1

Adjunctive Measures:

Essential preventive strategies: 1

• Cover active tinea pedis with socks before wearing underwear to prevent autoinoculation 1
• Complete drying of groin folds after bathing 1
• Use separate clean towels for groin and other body areas 1
• Daily changes of underwear 1

For Granular Parakeratosis (if biopsy-confirmed):

Treatment should be tailored to the underlying etiology: 4

• Identify and eliminate potential irritants or occlusive factors 4
• Mid to high-potency topical corticosteroids may be beneficial 4
• Consider topical keratolytics for verrucous lesions 4

Critical Pitfalls to Avoid

Do not use prolonged high-potency topical corticosteroids in the groin, as this can cause skin atrophy and worsen fungal infections 3

Do not assume all groin eruptions are fungal—pityriasis versicolor can mimic erythrasma in the groin, and vice versa, requiring mycological examination to avoid diagnostic errors 6

In immunocompromised patients with verrucous lesions, consider biopsy early to exclude invasive fungal infection, HPV-related neoplasia, or opportunistic infections 5, 2

Ensure treatment of concurrent tinea pedis to prevent reinfection of the groin 1