A Rare Infection in a Patient with Systemic Lupus Erythematosus Treated with Mycophenolate Mofetil

Area of Science:

• Infectious Diseases
• Dermatology
• Immunology

Background:

• Mycobacterium haemophilum is a rare, slow-growing nontuberculous mycobacteria primarily affecting immunocompromised individuals.
• Fewer than 250 cases have been documented since its 1978 discovery, highlighting its rarity.
• Cutaneous manifestations can be mistaken for other conditions, complicating diagnosis.

Purpose of the Study:

• To report a rare case of disseminated Mycobacterium haemophilum infection in an immunocompromised patient.
• To emphasize the diagnostic challenges and the importance of timely skin biopsy.
• To highlight the utility of advanced identification techniques in diagnosing fastidious organisms.

Main Methods:

• Case report of a 69-year-old female with systemic lupus erythematosus on mycophenolate mofetil.
• Clinical presentation of worsening skin nodules, lower limb edema, and proteinuria.
• Skin biopsy with histopathology (granulomatous inflammation, acid-fast bacilli) and MALDI-TOF mass spectrometry for organism identification.

Main Results:

• The patient presented with subcutaneous nodules and ecchymosis, initially suspected as a lupus flare.
• Skin biopsy confirmed granulomatous inflammation with acid-fast bacilli.
• Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry identified the organism as Mycobacterium haemophilum.

Conclusions:

• Clinicians should maintain a high suspicion for mycobacterial infections, particularly cutaneous forms, in immunocompromised patients.
• Failure to respond to standard treatments warrants prompt skin biopsy for diagnosis.
• Advanced identification methods like MALDI-TOF are essential for diagnosing challenging mycobacterial infections and guiding therapy.