Differential Diagnosis for Elderly Female with Asymmetrical Muscle Weakness, High Inflammatory Markers, and Elevated CPK and LDH

• Single Most Likely Diagnosis
  • Polymyositis: This is an inflammatory muscle disease characterized by muscle weakness, predominantly affecting the proximal muscles, and elevated muscle enzymes such as CPK and LDH. The asymmetrical nature of the weakness and high inflammatory markers support this diagnosis, as polymyositis often presents with such features in elderly females.
• Other Likely Diagnoses
  • Dermatomyositis: Similar to polymyositis but distinguished by the presence of skin manifestations. The muscle weakness and elevated enzymes are consistent with this diagnosis, but the absence of skin findings might make it less likely than polymyositis.
  • Inclusion Body Myositis (IBM): The most common acquired myopathy in adults over 50, characterized by progressive muscle weakness and wasting, particularly affecting the distal muscles. Elevated CPK levels and the presence of inflammatory markers could support this diagnosis, although IBM tends to have a slower progression.
• Do Not Miss Diagnoses
  • Lymphoma: Certain types of lymphoma can cause muscle weakness and elevated inflammatory markers. Although less common, missing a diagnosis of lymphoma could have significant implications for treatment and prognosis.
  • Rhabdomyolysis: A serious syndrome due to direct or indirect muscle injury, leading to the death of muscle fibers. It presents with muscle weakness, elevated CPK, and can have high inflammatory markers. Prompt recognition is crucial due to the risk of acute kidney injury.
• Rare Diagnoses
  • Mitochondrial Myopathies: A group of disorders caused by mutations in the mitochondrial DNA affecting muscle tissue. They can present with muscle weakness and elevated CPK but are less likely given the acute presentation and high inflammatory markers.
  • Toxic Myopathies: Certain drugs and toxins can cause muscle damage, leading to weakness and elevated muscle enzymes. The history might not always suggest exposure, making this a diagnosis to consider, especially if other causes are ruled out.