Docetaxel associated myositis.

Area of Science:

• Oncology
• Neurology
• Pathology

Background:

• Docetaxel is a taxane chemotherapy agent used for various cancers.
• While myalgia is a common side effect, docetaxel-induced myositis is rare.
• This case highlights a severe adverse event in breast cancer treatment.

Purpose of the Study:

• To report a rare case of docetaxel-induced myositis in a breast cancer patient.
• To emphasize the importance of recognizing this severe adverse drug reaction.

Main Methods:

• A 64-year-old female with HER2-positive breast cancer received neoadjuvant chemotherapy with docetaxel, trastuzumab, and pertuzumab.
• The patient presented with severe muscle pain and weakness after the second cycle.
• Diagnostic workup included physical examination, laboratory tests (elevated CK), MRI, and muscle biopsy.

Main Results:

• The patient developed significant muscle weakness (1/5 in lower extremities) and elevated creatine kinase (4389 U/L).
• MRI revealed intense edema in the lower extremities.
• Muscle biopsy confirmed drug-associated necrotizing myopathy.

Conclusions:

• Docetaxel-induced myositis is a rare but serious complication of chemotherapy.
• Clinicians must maintain a high index of suspicion for myositis in patients on docetaxel, especially those with concerning symptoms.