|
Anew muscle disease called macrophagic myofasciitis is
being seen with increasing frequency in France. As reported in the journal The Lancet
(August 1, 1998) by Gherardi and colleagues, the first case was identified in 1993.
Seventeen additional cases have been evaluated through 1997 in several French centers for
the study and treatment of muscle disorders.
Macrophagic myofasciitis is named for the findings seen in tissue from
muscle biopsies. Microscopic examination has shown an abnormal infiltrate of specialized
immune cells called macrophages surrounding muscle tissue. Macrophages are a type of
immune cell that is important for swallowing and destroying microorganisms. They also
assist other immune cells in the body’s response to invading organisms. The muscle
cells involved in patients with this disease appear to be minimally damaged by the
macrophages.
Muscle pain is the most frequent symptom.
This can be localized to the limbs or be more diffuse. Other symptoms include joint pain,
muscle weakness, fatigue, fever, and muscle tenderness.
The disorder is associated with an
altered immune system in some, but not all, patients. A significant number of patients
with macrophagic myofasciitis had taken chloroquine or hydroxychloroquine for malaria;
these drugs are known to inhibit the secretion from macrophages of a cell messenger
molecule called interleukin.
The cause of macrophagic myofasciitis has
not been identified despite fairly extensive investigations into known infectious and
immune disorders which might cause muscle disease. A unique material that accumulates
within the affected macrophages has been seen on electron microscopy. This material has
yet to be characterized.
Most of the patients with macrophagic
myofasciitis have responded to treatment with antibiotics and/or steroids within a few
days or weeks. One patient with macrophagic myofasciitis and evidence of tuberculosis
exposure recovered following treatment of the tuberculosis with four drugs.
With macrophagic myofasciitis, a
mysterious new disease of muscle has been identified.
|
