Atypical presentation of anti-small ubiquitin-like modifier 1 and melanoma differentiation-associated gene 5 antibody positive dermatomyositis presenting with significant inflammatory myopathy on biopsy and normal creatine kinase levels: A case report

Srikar Sama; Nidaa Rasheed; Kyle Shen; Negar Khanlou; Karam Han; Alicia Rodriguez-Pla

doi:10.1177/2050313X241298862

Atypical presentation of anti-small ubiquitin-like modifier 1 and melanoma differentiation-associated gene 5 antibody positive dermatomyositis presenting with significant inflammatory myopathy on biopsy and normal creatine kinase levels: A case report

SAGE Open Med Case Rep. 2024 Nov 12:12:2050313X241298862. doi: 10.1177/2050313X241298862. eCollection 2024.

Authors

Srikar Sama¹, Nidaa Rasheed¹, Kyle Shen², Negar Khanlou³, Karam Han³, Alicia Rodriguez-Pla⁴

Affiliations

¹ Department of Internal Medicine, University of California San Francisco Fresno, Fresno, CA, USA.
² School of Medicine, University of California San Francisco Fresno, Fresno, CA, USA.
³ Department of Pathology, University of California Los Angeles, Los Angeles, CA, USA.
⁴ Department of Rheumatology, University of California San Francisco Fresno, Fresno, CA, USA.

Abstract

Idiopathic inflammatory myopathies are characterized by chronic inflammation of skeletal muscle. The main subtypes of idiopathic inflammatory myopathies include dermatomyositis, polymyositis, and necrotizing autoimmune myopathies. Dermatomyositis is characterized by symmetrical proximal muscle weakness, distinctive skin lesions, and systemic manifestations. Dermatomyositis commonly presents with elevated creatinine kinase levels. However, we report a case of a 19-year-old female presenting with dermatomyositis positive for anti-small ubiquitin-like modifier 1 and melanoma differentiation-associated gene 5 antibodies presenting with classic signs and symptoms like progressive proximal muscle weakness, dysphagia, hyperpigmented rash, and Gottron's papules but had severe inflammatory myopathy on muscle biopsy and normal creatinine kinase levels. This case emphasizes an atypical presentation of dermatomyositis where she did not have amyopathic dermatomyositis despite having a positive anti-melanoma differentiation-associated gene 5 antibody and normal creatinine kinase. This underscores the importance of history and physical examination despite contradictory laboratory results.

Keywords: Dermatomyositis; autoimmune myopathies; creatinine kinase; myositis-specific antibodies.

Publication types

Case Reports