P6021 - First Reported Case of Immune-Mediated Necrotizing Myopathy as a Paraneoplastic Manifestation of Hepatocellular Carcinoma

Mahmoud Barbarawi, MD¹, Rishika Trivedi, MD², Prince Shah-Riar, MD³, Ahmad Abdelkhalek, MD⁴, Zaid Barbarawi, MD⁵, Fabrice Yabit, MD⁴, Asif Zamir, MD, FACG⁶
1DHR Health in affiliation with University of Houston, Tilman J. Fertitta College of Medicine, McAllen, TX; 2DHR Health, McAllen, TX; 3DHR Health, Edinburg, Tx, McAllen, TX; 4Northwestern Medicine McHenry Hospital/Rosalind Franklin University, McHenry, IL; 5Jordan University of Science and Technology, McAllen, TX; 6DHR Health Gastroenterology, Edinburg, TX

Introduction: Immune-mediated necrotizing myopathy (IMNM) is a rare, aggressive inflammatory myopathy characterized by subacute proximal muscle weakness, markedly elevated creatine phosphokinase (CPK), and myofiber necrosis on biopsy. It is often associated with anti-HMG-CoA reductase or anti-SRP antibodies, especially in statin users, but can also present as a paraneoplastic syndrome. While IMNM has been reported in association with several malignancies—including gastrointestinal, lung, prostate, uterine, and hematologic cancers—there are no previously published cases linking IMNM to HCC.

Case Description/

Methods: A 73-year-old male with diabetes, hypertension, and a stable hepatic mass presented with 3 months of progressive bilateral lower extremity weakness, frequent falls, and new urinary and fecal incontinence. He also had chronic neck and back pain. On admission, he had elevated creatinine, CPK, and troponin. Neurological exam revealed symmetric proximal and distal weakness in the lower extremities with reduced reflexes. Imaging ruled out acute intracranial pathology; cervical spine MRI showed degenerative changes with canal stenosis, but these did not fully explain his clinical picture.

Anti-HMG-CoA reductase antibodies were negative despite statin use. Muscle biopsy confirmed immune-mediated necrotizing myopathy. Given the absence myositis-specific antibodies, a paraneoplastic etiology was pursued. Abdominal MRI revealed marked progression of a previously stable hepatic lesion, now an exophytic right lobe mass consistent with LI-RADS 5 HCC. The patient was deemed not a surgical candidate. He was initially treated with a 5-day IVIG course, leading to substantial improvement in strength. Interventional radiology performed Y90 radioembolization. However, the tumor persisted. Recently, he underwent aggressive locoregional therapy with transarterial chemoembolization (TACE) for more effective tumor control.

Discussion: While IMNM is an established paraneoplastic entity, its occurrence secondary to HCC has not been previously reported. This case underscores the importance of considering malignancy in the differential diagnosis of seronegative necrotizing myopathy. Although IVIG provided initial neurologic improvement, the patient’s myopathy worsened over time, likely due to ongoing tumor burden and lack of definitive oncologic control. He ultimately became wheelchair-bound pending more effective HCC-directed therapy. This case aims to expand the spectrum of HCC-associated paraneoplastic syndromes.


Figure: Figure 1. Abdominal MRI showing a large exophytic mass in the right hepatic lobe with arterial phase hyperenhancement and washout, meeting LI-RADS 5 criteria and consistent with hepatocellular carcinoma


Figure: Figure 2. Hematoxylin and eosin-stained muscle biopsy demonstrating scattered necrotic and regenerating muscle fibers with minimal inflammatory infiltrate, consistent with immune-mediated necrotizing myopathy

Disclosures:
Mahmoud Barbarawi indicated no relevant financial relationships.
Rishika Trivedi indicated no relevant financial relationships.
Prince Shah-Riar indicated no relevant financial relationships.
Ahmad Abdelkhalek indicated no relevant financial relationships.
Zaid Barbarawi indicated no relevant financial relationships.
Fabrice Yabit indicated no relevant financial relationships.
Asif Zamir indicated no relevant financial relationships.

Mahmoud Barbarawi, MD¹, Rishika Trivedi, MD², Prince Shah-Riar, MD³, Ahmad Abdelkhalek, MD⁴, Zaid Barbarawi, MD⁵, Fabrice Yabit, MD⁴, Asif Zamir, MD, FACG⁶. P6021 - First Reported Case of Immune-Mediated Necrotizing Myopathy as a Paraneoplastic Manifestation of Hepatocellular Carcinoma, ACG 2025 Annual Scientific Meeting Abstracts. Phoenix, AZ: American College of Gastroenterology.