Cytopathology Conference

12/01/2005

Case 1

• Pericardial fluid from a 36-year-old female with a history of lupus and a pericardial effusion.

A special stain was performed…

Diagnosis?

Differential Diagnosis

• Idiopathic pericarditis

• Lupus pericarditis

• Pericarditis due to mycobacterium species

• Pericarditis due to gram negative species

Lupus Pericarditis:pericardial fluid positive forMycobacterium mucogenicum

Mycobacterium mucogenicum

• Designated as a new species in 1995– Member of Mycobacterium fortuitum-

chelonae complex.

• Belongs to group IV of the Runyon Classification of nontuberclous mycobacteria (NTM).

Mycobacteria

Mycobacterium tuberculosis

complex

Nontuberculous mycobacteria

Mycobacterium tuberculosis

Mycobacterium bovis

Mycobacterium africanum

Runyon Classification

I) Photochromogens

II) Scotochromogens

III) Nonphotochromogens

IV) Rapid-growers

Mycobacterium mucogenicum

• All Runyon group IV members:

– Acid fast– Don’t produce pigment– Growth: < 7days– Produce arylsufatase after 3 days of growth– Growth at 28 degrees on crystal violet neg.

MacConkey agar

Mycobacterium mucogenicum• Identified as a water contaminant in the

hospital setting.

• Nosocomial infections: post-surgical, catheter related, hemodialysis.

• Commensal organism: found on skin

Mycobacterium mucogenicum• Identification:

– Unique 16s ribosomal unit

– Mycobacterial membrane fatty acid composition:• Resistant to INH and rifampin• Susceptible in vitro to quinolones, amikacin,

imipenim and Bactrim

Microscopic Appearance

• I) M kansasii: long, curved or folded and beaded

• II) M scrofulaceum: very short and delicate

• III) MAC: short, thick and beaded

• IV) M fortuitum: long and filamentous