SHM Converge Scientific Abstract ePoster Gallery-When Muscles Speak: Necrotizing Myopathy as the First Sign of Lung Cancer

Pdf Summary

A 61-year-old man with a history of tobacco use presented with 2 months of progressive, symmetric proximal muscle weakness. He denied constitutional, respiratory, and skin symptoms, making the diagnosis less obvious. Initial labs showed markedly elevated muscle enzymes and inflammation markers, including CK 11,693 U/L and AST/ALT in the 300s, while other liver tests were normal. EMG suggested an irritative myopathy, and right thigh biopsy demonstrated myonecrosis, myophagocytosis, and regenerating fibers with minimal inflammation, consistent with seronegative immune-mediated necrotizing myopathy (IMNM).<br /><br />Because seronegative IMNM can be associated with cancer, further evaluation was performed. CT imaging and fine-needle aspiration of a left supraclavicular lymph node revealed non-small cell lung carcinoma. The patient was treated with high-dose methylprednisolone and intravenous immunoglobulin, leading to improvement in CK.<br /><br />This case highlights paraneoplastic seronegative IMNM as the first sign of an occult lung cancer. It emphasizes that elevated AST/ALT in the setting of proximal weakness and high CK may reflect muscle injury rather than liver disease. Early recognition of this pattern is important because prompt biopsy, malignancy screening, immunotherapy, and multidisciplinary care can preserve function and reduce irreversible muscle damage.

Asset Subtitle

Christine Lin

Meta Tag

Author List Ashley A. Narsinghani, Brittany Doll, Christine Lin

Category Clinical Vignettes

Concept Immune-Mediated Necrotizing Myopathy

Concept Proximal Muscle Weakness

Concept Creatine Kinase

Concept Symmetric Weakness

Concept Muscle Biopsy

Distinguished Non-Finalist

Presenter Organization Rush Medical College

Presenting Author Christine Lin

Track Adult

Keywords

seronegative IMNM

immune-mediated necrotizing myopathy

proximal muscle weakness

elevated creatine kinase

myonecrosis

myophagocytosis

paraneoplastic syndrome

non-small cell lung carcinoma

muscle biopsy

iv immunoglobulin

Immune-Mediated Necrotizing Myopathy

Proximal Muscle Weakness

Creatine Kinase

Symmetric Weakness

Muscle Biopsy