An 83-year-old man with cholangiocarcinoma developed immune checkpoint inhibitor-associated myositis after two cycles of durvalumab, presenting with muscle weakness and myalgia. His serum creatine kinase (CK) level peaked at 26,329 U/L. Needle electromyography confirmed a myogenic process, and MRI revealed extensive muscle edema. Muscle biopsy indicated multifocal necrotic fibers. Following steroid treatment, his CK levels normalized and muscle strength returned. This case represents the first reported instance of durvalumab-associated myositis in Korea.

Valosin-containing protein (VCP)-related multisystem proteinopathy (MSP1) is a rare genetic disorder marked by abnormal protein accumulation. This study presents the case of a 52-year-old woman with MSP1, showing progressive weakness, gait disturbances, and respiratory muscle weakness over five years. The clinical examination revealed diverse presentations, including neurogenic changes in electrophysiologic study, multifocal fatty changes of muscle, and cognitive impairment with a confirmed VCP gene mutation through genetic testing. Notably, we identified lobulated myofibers in the muscle biopsy, an unusual finding in MSP1. This is the first report of lobulated myofibers in MSP1 with multisystem involvement. Identifying unique muscle biopsy results in suspected MSP1 patients through careful neurological examinations and timely genetic testing may help in early diagnosis and appropriate management.

Inclusion body myositis (IBM) is a late-onset myopathy that manifests as distinct muscle weakness in the quadriceps, finger flexors, and ankle dorsiflexors. T-cell large granular lymphocyte (T-LGL) leukemia is a late-onset clonal disorder of CD8+ cytotoxic T-cells that is often accompanied by autoimmune diseases. To date, the association between IBM and T-LGL leukemia has been infrequently reported. Here, we report a case of a patient with T-LGL leukemia who developed IBM, along with in-depth laboratory, electrophysiological, and pathologic findings.

Overlap myositis (OM) associated with Sjögren’s syndrome (SS) is a relatively uncommon disorder. It is more difficult to detect OM when a patient had not been previously diagnosed with SS. We report a case of OM associated SS that initially presented with dysphagia followed by proximal weakness. If proximal muscle weakness is preceded by dysphagia, the possibility of OM associated with connective-tissue disease should be considered.

We report a case of a 75-year-old woman who was diagnosed with dermatomyositis presenting with isolated dysphagia. There were no obvious cranial nerve deficits with normal motor grade in all the limbs in neurological examinations, but a suspicious rash was observed in the anterior chest. The serum creatine kinase was 306 IU/L, and active myopathic changes in bilateral limb muscles were observed in the electromyography test. Muscle biopsy from vastus lateralis showed perivascular infiltration of mononuclear inflammatory cells, which was compatible with dermatomyositis. She had responded to oral prednisolone and azathioprine.

Idiopathic orbital myositis is considered as a subgroup of idiopathic orbital inflammatory disease. It is a non-infectious inflammatory disorder primarily affecting the extraocular muscles and causes various eye symptoms including pain, diplopia and limitation of extraocular movement. Cases of isolated ptosis by idiopathic orbital myositis have been very rarely described in the literature. We report a patient who developed unilateral painless ptosis caused by idiopathic orbital myositis. A 52-year-old man presented with drooping of the right eyelid for 3 days. There was no history of headache, double vision or any other complaints. Neurological examination revealed right ptosis without pupil and extraocular muscles involvement. Repetitive nerve stimulation test was normal. Ptosis did not improve after the neostigmine injection. Magnetic resonance imaging scan showed asymmetric enlargement of right superior rectus/levator palpebrae superioris muscle complex and medial rectus muscle. Ptosis resolved dramatically after oral corticosteroid therapy. Isolated unilateral ptosis can be caused by various etiologies. Idiopathic orbital myositis should be considered in the differential diagnosis of ptosis.

Citations

• Isolated Unilateral Ptosis Caused by Orbital Myositis Involving the Superior Rectus-Levator Muscle
  Woonghee Kim, Eun Hye Jung
  Annals of Optometry and Contact Lens.2022; 21(2): 75.     CrossRef

Focal eosinophilic myositis (FEM) is the most limited form of eosinophilic myositis that commonly affects the muscles of the lower leg without systemic manifestations. We report a patient with FEM who was studied by magnetic resonance imaging and muscle biopsy with a review of the literature.

Citations

• Origins and functions of eosinophils in two non-mucosal tissues
  Katie S. Day, Lucas Rempel, Fabio M. V. Rossi, Marine Theret
  Frontiers in Immunology.2024;[Epub]     CrossRef

Acute sarcoid myositis is rarely complicated by sarcoidosis, and steroid therapy is considered the standard treatment. We experienced a patient with acute sarcoid myositis who did not respond to aggressive high-dose corticosteroid therapy, but showed a dramatic improvement after the addition of weekly low-dose oral methotrexate (MTX). This intervention allowed the resumption of normal daily activities after 6 months. Our case strongly suggests that MTX should be considered in patients with acute sarcoid myositis that is resistant to corticosteroid therapy.

Influenza B virus infections appear to be more common extra-respiratory tract symptoms, compared to influenza A virus infections. Benign acute childhood myositis (BACM) is a benign disease that is caused mainly by many viruses like influenza A or B virus infection. Usually BACM is fully cured with only supportive treatment without unnecessary investigation or invasive procedure. This report describes an eight-year-old boy with acute bilateral calf pain and walking difficulty who diagnosed with BACM after influenza B virus infection.

Focal myositis is a benign inflammatory pseudotumor of a skeletal muscle that clinically mimics a tumor of soft tissue, but the cause of which is obscure. I report here a case of multifocal recurrent nonpainful myositis found in a 68-years-old man who showed a subacute multifocal recurrent nonpainful inflammatory myopathy affecting discrete muscle groups with spontaneuous remission and/or some medication.

Sporadic inclusion body myositis (s-IBM) is an aquired slowly progressive inflammatory myopathy with unknown etiology. Although light microscopic abnormalities and characteristic histopathology on muscle biopsy distinguishes from other inflammatory myopathies, vacuolated muscle fibers, intracellular amyloid deposits or tubulofilaments in electromicroscopic findings are not definite in some patients. This review shows the prominently involved muscles in s-IBM and specific or nonspecific electrophysiologic manifestations from reported data for helping the diagnosis of definite-or probable-IBM patients. In lower limbs, the quadriceps is predominantly involved, as is iliopsoas, and tibialis anterior is common. In the upper limbs, the greatest weakness is in forearm finger flexors. Finger extensors, biceps and triceps also are moderately to prominently involved. The majority of patients demonstrate polyphasic MUAPs that are short in duration. An additional striking feature is the concomitant documentation of long-duration, large-amplitude, polyphasic MUAPs. In spite of the frequent mixed myopathic-neurogenic electromyographic findings of IBM, just like that of chronic myositis, asymmetric, slowly progressive weakness of flexor digitorum profundus or quadriceps femoris muscles after age of 50 is very necessary condition for the diagnosis of IBM.

It has been reported that antisynthetase syndrome belongs to the idiopathic myositis group which includes pulmonary interstitial disease, arthritis, Raynaud

Background: The term

The inflammatory myopathies are divided into three major and distinct subsets as polymyositis(PM), dermatomyositis(DM), and inclusion body myositis(IBM). This distinction is based on unique clinical, demographic, laboratory, histologic,therapeutic, prognostic, and immunopathologic criteria.Although the causes of PM, DM, and IBM are unknown, autoimmune mechanisms are implicated, as supported bytheir association with other putative or definite autoimmune diseases or viruses, the evidence for a T cell-mediatedmyocytotoxicity or complement-mediated microangiopathy, the presence of various autoantibodies and their responseto immunotherapies. But in IBM the immune-mediated process is weaker and IBM patients do not readily respond toimmunotherapies, there are convincing immunopathological signs to suggest that a definite autoimmune component,similar to that seen in PM, also plays a role in the cause of IBM.

Among drug-induced myopathy, steroids are probably the most common cause. The risk of steroid myopathy(SM)increases with the dose and duration of use. It is typically a proximal myopathy, preferentially affecting the hip girdlemuscles. Motor and sensory nerve conduction studies are normal. The needle EMG is usually within the normal rangeor may be minimally abnormal. Occasionally, low-amplitude, short-duration MUAPs may be seen in the proximal muscles.Of note, abnormal spontaneous activity is not seen. This point is often very useful in differentiatingpolymyositis(PM) from SM. It is common for patients with PM to be treated with steroids, respond well, and then havethe steroids tapered. If muscle weakness then returns, it may be very difficult to differentiate recurrent PM from SM onclinical grounds. The presence of abundant abnormal spontaneous activity strongly suggests PM rather than SM.

Chronic graft-versus-host disease (GVHD) is a well-known complication of allogeneic bone marrow transplantation (BMT)and has heterogeneous manifestations, with multi-organ involvement. Recently, polymyositis (PM) was reported to be a raremanifestation of chronic GVHD. Here, we report a 30-year-old woman who was diagnosed with PM after allogeneic BMT.