University of Arizona College of Medicine Phoenix, AZ
Award: Presidential Poster Award
Vanessa F. Eller, MD1, Kyle Pierce, DO2, Dayna Telken, DO3, Kyle S.. Conway, MD4, Mark Wong, MD3 1University of Arizona College of Medicine, Phoenix, AZ; 2University of Arizona College of Medicine, Phoenix VA Medical Center, Phoenix, AZ; 3Banner University Medical Center, Phoenix, AZ; 4University of Michigan Medical School, Ann Arbor, MI
Introduction: Individuals with ulcerative colitis (UC) are frequently burdened by the extraintestinal manifestations of their UC which can include involvement of dermatological, ophthalmologic, hepatic and musculoskeletal systems. These manifestations have a significant impact on morbidity, even more so than the underlying irritable bowel disease (IBD). In this case, we present a patient with UC diagnosed with seronegative immune-mediated necrotizing myositis (IMNM), a novel extraintestinal manifestation of UC.
Case Description/Methods: A 65-year-old male with a 25-year history of UC on immunosuppressive therapy and undergoing chronic steroid taper presented with rapidly progressive, generalized muscular weakness. On exam, the patient had 0/5 strength with both flexion and extension of his bilateral hips and knees and 0/5 strength with arm abduction and adduction. Labs on presentation revealed white blood cell count 17 K/uL, creatinine 8.97 mg/dL, creatinine kinase 17,973 U/L, and C-reactive peptide 43.5 mg/L. An extensive myositis panel was done which was unremarkable with a negative anti-signal recognition particle (anti-SRP) and negative anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR). A muscle biopsy revealed severe necrotizing myopathy (Figure) and he was diagnosed with seronegative IMNM. He was treated with 5 days of intravenous immunoglobulin (IVIg) therapy with only mild improvement of his symptoms. The patient's hospitalization was complicated by rectal bleeding, leading to sigmoidoscopy which demonstrated active left-sided colitis with a fecal calprotectin of 478 mcg/g. Despite treatment with mesalamine and a second course of IVIg, the muscle atrophy continued to progress and led to the patient’s demise.
Discussion: Myositis is a rare manifestation of IBD that has been found to be more closely associated with Crohn’s disease than UC. There have been 12 cases linking UC with myositis, none of which were categorized as necrotizing myositis. The patient in this case was diagnosed with seronegative IMNM which is distinguished from other types of myositis due to the necrotic myofibers on biopsy and is further classified according to the presence of autoantibodies, specifically anti-SRP and anti-HMGCR. In general, the prognosis of seronegative IMNM is worse than the other inflammatory myopathies and proper diagnosis is essential. To our knowledge, IBD has been linked with multiple extraintestinal manifestations including myositis, but it has not been associated with seronegative IMNM.
Figure: FIGURE: Left quadriceps muscle biopsy findings. (A) Section stained with hematoxylin and eosin shown at high power showing numerous necrotic fibers (arrow) without significant endomysial inflammation. (B) Major histocompatibility (MHC) Class 1 shows patchy, focal sarcolemmal expression. (C) Complement C5b-9 highlights necrotic fibers and shows granular sarcolemmal expression on rare viable fibers (arrow). (D) p62 shows numerous fibers with a punctate granular sarcoplasmic pattern of staining. The findings together are diagnostic of a severe necrotizing myopathy; the pattern of p62 expression, focal MHC class 1 expression, and rare granular sarcolemmal C5b-9 deposition favor a diagnosis of immune-mediated necrotizing myopathy (IMNM). Magnifications: x400 [A], x100 [B, C, D].
Disclosures:
Vanessa Eller indicated no relevant financial relationships.
Kyle Pierce indicated no relevant financial relationships.
Dayna Telken indicated no relevant financial relationships.
Kyle Conway indicated no relevant financial relationships.
Mark Wong: Gilead – Speakers Bureau.
Vanessa F. Eller, MD1, Kyle Pierce, DO2, Dayna Telken, DO3, Kyle S.. Conway, MD4, Mark Wong, MD3. P1005 - An Unexpected Extraintestinal Manifestation of Ulcerative Colitis: Seronegative Necrotizing Myositis, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.
