Progressive Arm Lesion: From Suspected Contact Dermatitis to Diagnostic Challenge

Case at a Glance

A 38-year-old male presents with a progressive arm lesion that initially appeared consistent with poison ivy contact dermatitis but failed to respond to standard treatments and evolved into a more complex dermatological condition.

Patient's Story

The patient, a 38-year-old male from Michigan (height 5'7", weight 185 lbs, non-smoker, no regular medications), initially developed what he believed to be poison ivy on his left bicep. He recalls experiencing intense itching one night and scratching the area, though he's uncertain whether there was an initial lesion present before scratching. The patient considered the possibility of an insect bite but cannot recall a specific incident.

Initial Assessment

The patient was initially diagnosed with poison ivy contact dermatitis based on his history and clinical presentation. Physical examination revealed a localized erythematous lesion on the left bicep with a central red spot. The patient was prescribed a 5-day course of prednisone for presumed allergic contact dermatitis.

The Diagnostic Journey

After 5 days of prednisone treatment, the lesion showed no improvement and possibly worsened. Given the lack of response to corticosteroids, the differential diagnosis was expanded to include fungal infection. Topical antifungal cream was initiated; however, after 2 days of treatment, no clinical improvement was observed. The lesion continued to evolve over the course of a week, with photographic documentation showing progressive changes from Wednesday through Sunday to the current presentation.

Final Diagnosis

Diagnosis pending - lesion of unknown etiology with differential including atypical contact dermatitis, secondary bacterial infection, fungal infection, arthropod bite reaction, or other inflammatory dermatosis requiring further evaluation.

Treatment Plan

Initial treatment with oral prednisone (5-day course) followed by topical antifungal therapy. Given the lack of response to both treatments, further diagnostic workup including bacterial culture, fungal culture, and possible biopsy may be warranted. Consider dermatology consultation for definitive diagnosis and management.

Outcome and Follow-up

Patient continues to monitor the lesion with photographic documentation. The condition remains unresolved after initial treatments, necessitating ongoing medical evaluation and potential alternative therapeutic approaches based on further diagnostic findings.