Isolated necrotizing myopathy associated with ANTI-PL12 antibody.

Area of Science:

• Immunology
• Neurology
• Rheumatology

Background:

• Immune-mediated myopathies encompass chronic autoimmune disorders characterized by myositis-specific and myositis-associated autoantibodies.
• Anti-tRNA synthetase antibodies, particularly anti-PL12, are key myositis-specific autoantibodies often linked to systemic connective tissue disorders.

Observation:

• A 49-year-old male presented with progressive difficulty in walking and climbing stairs over five months.
• The patient exhibited no cutaneous manifestations such as rash or skin changes.

Findings:

• Laboratory tests confirmed the presence of anti-PL12 autoantibodies.
• Despite positive anti-PL12 antibodies, the patient tested negative for connective tissue disorders (CTD).
• The patient was diagnosed with necrotizing myopathy associated with anti-PL12 antibodies, notably without inflammatory biopsy findings, significant muscle enzyme elevation, or typical CTD features.

Implications:

• This case underscores the importance of suspecting immune-mediated necrotizing myopathy even when connective tissue disease is not apparent.
• Maintaining a high index of suspicion for anti-PL12-associated necrotizing myopathy is crucial, particularly in cases with atypical or milder clinical presentations.