A 'polymyalgia' in a man in his 70s turned out to be melanoma from a toe lesion
Shoulder and hip pain suggested polymyalgia rheumatica, but a very high creatine kinase led to dermatomyositis, lymph node melanoma, and finally a toe lesion once blamed on trauma.
A man in his late 70s had six weeks of pain and stiffness in both shoulders and hips, plus marked weight loss. Polymyalgia rheumatica seemed likely, but the weight loss triggered an urgent cancer referral while tests ran in parallel.
His creatine kinase was above 5000 U/L, he had proximal weakness and subtle skin changes, pointing to dermatomyositis. A CT scan showed extensive abdominal and groin lymph node enlargement, first suggesting lymphoma. A needle biopsy of a node instead showed metastatic melanoma. Only then did a skin and nail examination reveal a pigmented lesion on the right great toe, earlier attributed to trauma, consistent with the primary acral melanoma.
The final diagnosis was paraneoplastic dermatomyositis mimicking a polymyalgia-like syndrome. After corticosteroids and BRAF/MEK targeted therapy, his muscle symptoms resolved and imaging showed a response. This is a single case report, so it illustrates a pattern rather than showing how often it occurs.
Summary prepared with AI assistance from the published abstract and reviewed by a physician. Not medical advice. Learn more
