Clinical Features:

• Defined as infections caused by Mycobacterium species other than M. tuberculosis and M. leprae.
• The most common organisms causing cutaneous infection are M. marinum (swimming pool granuloma), M. ulcerans (Buruli ulcer; found in Central Africa), M. avium-intracellulare (MAI; most commonly seen in patients with AIDS), M. fortuitum and M. chelonei.
• The lesions may present as abscesses, ulcers, nodules, verrucous plaques or sinus tracts, and may be solitary or multiple.
• Lesions may spread in a fashion that resembles that of sprotrichosis.

Histologic Features:

• Suppurative granulomas with or without caseation
• The overlying epidermis may be hyperplastic or ulcerated.
• Fibrosis and granulation tissue are often present, and may be florid.
• Acid-fast stains may show the organisms.  The highest-yield location to them out is within microabscesses or vacuoles.
• More sensitive methods for identifying the acid-fast bacilli are fluorescent antibodies and PCR.

Cases associated with this book:

Diagnosing atypical mycobacterial infection of the skin can be very difficult
Author: Dr. Sate Hamza MD, FRCPC

Conference: The Dermpath-l Mailing List Conference

MAI
Author: Stephen Lyle, M.D., Ph.D.

Conference: Dermpedia Teaching Collection