Marked Respiratory Failure in an Ambulant Patient with Immune-mediated Necrotizing Myopathy and Anti-Kv1.4 and Anti-titin Antibodies

Abstract

We herein report a case of seronegative immune-mediated necrotizing myopathy (IMNM) concurrent with anti-Kv1.4 and anti-titin antibodies. A 72-year-old Japanese woman presented with a 29-year history of fluctuating high serum creatine kinase (CK) levels followed by intermittent ptosis and respiratory muscle weakness. This case highlights the fact that marked respiratory muscle weakness requiring intubation can be seen in an ambulant patient with IMNM. Marked respiratory muscle weakness, rhabdomyolysis-like acute elevation of CK levels, and anti-striational muscle antibodies may be a characteristic constellation of findings in a distinct subgroup of patients with inflammatory myopathy with myasthenia gravis or similar symptoms.

Keywords: blepharoptosis; creatine kinase; muscular diseases; respiratory paralysis.

Figure 1.

Clinical course of the patient. CK: creatine kinase

Figure 2.

Histopathological findings of the left biceps brachii muscle. Hematoxylin and Eosin staining section showed a moderate variation in fiber size and scattered regenerating muscle fibers (A). Nicotinamide adenine dinucleotide (NADH) staining showed that the intermyofibrillar networks were mildly disorganized in some fibers with a moth-eaten appearance (B). Immunohistochemical staining showed the focal expression of human leukocyte antigen ABC (HLA-ABC) (C) and membrane attack complex (MAC) deposition on sarcolemma in some fibers (D).