Genetics and Environment

• According to the Mayo Clinic, the triggers of polymyalgia are not understood, but may result from a malfunction of the immune system (involving environmental and genetic factors).
  
  

Aging

• The natural process of aging also contributes to the development of polymyalgia.
  
  

Possible Form of Arthritis

• The American College of Rheumatology also notes that new evidence "suggests that PMR is an arthritis with a particular tendency to involve the shoulder and hip joints, and the bursae (or sacs) around these joints."
  
  

Viral Infection

• According to William C. Shiel, Jr., MD, medical writer for MedicineNet, one theory of polymyalgia involves the interaction between genetic factors and the environment: A person's immune system is stimulated by a viral infection.
  
  

Cancer Link

• Dr. Shiel also notes that, in rare cases, cancer is linked to polymyalgia. The cancer may cause an inflammatory immune response, manifesting as polymyalgia symptoms.