Diagnosis: Erythrasma
A 45-year-old male presents with a brown velvety patch in the groin that has persisted for several weeks. Examination reveals a well-defined, hyperpigmented lesion that fluoresces coral-red under Wood's lamp, suggestive of a superficial bacterial infection commonly seen in intertriginous areas.
A 45-year-old male presents with a brown velvety patch in the groin, which has been present for three weeks. The patient reports mild itching but no pain. On examination, a well-defined, brownish-red patch measuring approximately 5 cm is noted in the inguinal fold. The lesion exhibits a velvety texture and fluoresces coral-red under Wood's lamp.Location: Intertriginous areas, commonly the groin, axillae, or between toes.Appearance: Brownish to reddish-brown patches with a velvety texture.Fluorescence: Coral-red under Wood's lamp examination.Itching: Mild, often absent, differentiating it from other dermatoses.Demographics: More common in individuals with obesity, diabetes, or excessive sweating.
The patient reports the onset of the lesion approximately three weeks prior, with no significant triggering factors identified. He has a past medical history notable for Type 2 diabetes and is obese. He has not previously sought treatment for this condition. The patient lives in a warm, humid climate, which may contribute to the development of the condition. No family history of similar skin lesions is reported.Onset: Lesion developed over three weeks.Triggers: No identifiable triggers; living in a humid environment.Past Treatments: No prior treatments attempted.Medical History: Type 2 diabetes and obesity.Social History: Lives in a warm climate, no recent travel.
Acute / First-Line ManagementTopical antibiotics: Clindamycin 1% lotion applied twice daily for 1-2 weeks.Oral antibiotics: Doxycycline 100 mg orally twice daily for 7 days, especially in extensive cases.Hygiene measures: Keeping the affected area clean and dry to prevent recurrence.Workup and Diagnostic ConfirmationClinical examination: Detailed skin examination and assessment of other intertriginous areas.Wood's lamp examination: To confirm coral-red fluorescence characteristic of the infection.Culture: Skin scrapings can be sent for culture of Corynebacterium minutissimum if diagnosis is uncertain.Long-Term ManagementPreventive measures: Regular cleansing and drying of intertriginous areas.Weight management: Addressing obesity and diabetes to reduce recurrence risk.Follow-up: Regular follow-up to monitor for recurrence, especially in at-risk populations.
Intertrigo: Inflammatory condition in skin folds with red, macerated skin; usually lacks fluorescence.Tinea cruris: Fungal infection presenting with annular lesions; may have scaling and typically does not fluoresce.Psoriasis: Can present in folds; features silvery scales and chronicity distinguishes it.Contact dermatitis: Erythematous patches due to irritants or allergens; history of exposure helps differentiate.Inguinal lymphadenopathy: May present with similar skin findings; systemic symptoms and regional lymphadenopathy are key features.Seborrheic dermatitis: Presents as scaly patches, usually with greasy appearance; more chronic and often involves scalp.Cutaneous candidiasis: Yeast infection in folds with bright red appearance and satellite lesions; typically does not fluoresce.Acne inversa (hidradenitis suppurativa): Chronic inflammatory condition with painful nodules and abscesses; more extensive lesions and scarring.
High-Yield PearlsFluorescence: The characteristic coral-red fluorescence under Wood's lamp is a key diagnostic feature.Intertriginous areas: Erythrasma commonly occurs in warm, moist areas such as the groin and axillae.Prevention: Maintaining dryness and hygiene in skin folds is crucial in preventing recurrence.Underlying conditions: Obesity and diabetes are significant risk factors for the development of erythrasma.First-line treatment: Topical clindamycin or oral doxycycline are effective initial therapies.In cases of brown patches in intertriginous areas, remember to consider erythrasma, especially if the lesion fluoresces coral-red under Wood's lamp.
Tags: erythrasma, Corynebacterium