A 27-Year-Old Man with a Lesion on One Hand

Differential Diagnosis

• Bacterial abscess
• Cutaneous anthrax
• Granuloma annulare
• Mycobacterium marinum infection
• Vasculitis

Diagnosis

This patient was diagnosed with Mycobacterium marinum infection, an atypical mycobacterial skin infection often contracted from contaminated fish tanks, swimming pools, and, occasionally, ocean or lake water.

 

Learnings

• The typical skin lesion consists of a pustule or nodule and develops on the exposed extremity 2─3 weeks after exposure
• Constitutional symptoms are rare; fever, if present, is typically low-grade

 

Pearls for Urgent Care Management and Considerations for Transfer

• The disease is usually self-limited, and lesions tend to heal over a period of 1─2 years if left untreated
• Patients with AIDS, organ transplant recipients, and patients on chronic steroids may occasionally develop disseminated infections to the skin, bone marrow, and joints, leading to synovitis and arthritis

 

Acknowledgment: This case is presented courtesy of VisualDx.