Desminopathy is a cardiac and skeletal myopathy caused by disease-causing variants in the desmin (DES) gene and represents a subgroup of myofibrillar myopathies, where cytoplasmic desmin-postive immunoreactivity is the pathological hallmark. We herein report a 28-year-old Japanese man who was initially diagnosed with sporadic hypertrophic cardiomyopathy with atrioventricular block at 9 years old and developed weakness in the soft palate and extremities. The myocardial tissue dissected during implantation of the ventricular-assisted device showed a dilated phase of hypertrophic cardiomyopathy and intracellular accumulation of proteinase K-resistant desmin aggregates. Genetic testing confirmed a de novo mutation of DES, which has already been linked to desminopathy. As the molecular diagnosis of desminopathy is challenging, particularly if patients show predominantly cardiac signs and a routine skeletal muscle biopsy is unavailable, these characteristic pathological findings of endomyocardial proteinase K-resistant desmin aggregates might aid in clinical practice.

Scleredema is a rare cutaneous mucinosis characterized by diffuse swelling and non-pitting induration. A 63-year-old man reported a 5-year history of skin thickening of the trunk and a 3-week history of dyspnea. Echocardiography revealed diffuse hypokinesis. Skin biopsies obtained from the waist showed thickened dermis with mucin. Myocardial biopsies showed alcian blue-stained tissue between the muscle fibers. The patient was referred to a dermatologist for phototherapy. Cardiomyopathy should be considered in patients with scleredema. Scleredema usually has a good prognosis; however, the mortality risk could be high when accompanied by cardiomyopathy.

Multisystem Inflammatory Syndrome (MIS) is a novel hyperinflammatory syndrome associated with SARS-CoV-2 infection. It predominantly affects children (MIS-C) a few weeks after a usually asymptomatic SARS-CoV-2 infection and is only rarely seen in adults above 21 years (MIS-A). Only scarce data on histological findings in both pediatric and adult patients has been published so far. An 18-year-old male patient was admitted to hospital in a febrile state, which progressed to severe cardiogenic shock and multi-organ failure requiring extracorporeal life support. Myocardial biopsy revealed small vessel-associated immune cell infiltrates. Diagnosis of MIS-C was made after ruling out all potential differential diagnosis. Use of immunosuppressive treatment with steroids, interleukin-1 blockade and high-dose intravenous immunoglobulins resulted in the patient\'s full recovery. Multisystem Inflammatory Syndrome (MIS) is a new differential diagnosis of cardiac dysfunction in pediatric and adult patients. The lack of myocardial necrosis differentiates the disease from other viral myocarditis and offers an explanation for the fast response to immunomodulatory therapy and the favorable prognosis. The preceding SARS-CoV-2 infection might only have been mildly symptomatic or even asymptomatic.

A 73-year-old woman with a history of diarrhea for one year and other various symptoms was admitted to our hospital. Gastrointestinal endoscopy that included enteroscopy with multiple biopsies was performed. However, no significant findings were observed. Electrocardiography showed low voltage in all limb leads, and an echocardiogram showed thickened cardiac walls with granular sparkling pattern. A myocardial biopsy revealed amyloidosis, and a bone marrow biopsy showed multiple myeloma. This case suggests that we should suspect the possibility of amyloidosis in a patient with diarrhea and various symptoms involving multiple organ systems. Additionally, electrocardiograms and echocardiograms should be performed even when gastrointestinal biopsies reveal negative results.

UNASSIGNED: Eosinophilic myocarditis (EM) is rare but accounts for 12-22% of histologically proven acute myocarditis cases. Acute necrotizing EM is considered an aggressive, life-threatening disease which is usually treated by high-dose corticosteroid therapy.
UNASSIGNED: We report the case of a 27-year-old man with acute severe pericarditic chest pain, moderately reduced left ventricular (LV) ejection fraction, and a small pericardial effusion. Troponin I level was highly elevated in the absence of coronary artery disease, leading to the diagnosis of acute myopericarditis. In the absence of blood eosinophilia and despite a negative cardiac magnetic resonance study, LV endomyocardial biopsy revealed an acute necrotizing EM. With conventional antiphlogistic and heart failure therapy, the patient became symptom-free and inflammatory and cardiac necrosis markers as well as LV ejection fraction normalized within days. Thus, in the absence of a systemic hypereosinophilic disorder, there was no need for steroid therapy. Long-term follow-up over 12 months showed sustained normalization of cardiac structure and function.
UNASSIGNED: Acute necrotizing eosinophilic myopericarditis is not always a dreadful cardiac disease. There are idiopathic cases which may quickly resolve without immunosuppression. There seems to be a publication bias towards critical cases.

We report a case of lethal myocarditis and myositis after pembrolizumab treatment for advanced upper urinary tract urothelial carcinoma. A 69-year-old man underwent pembrolizumab therapy as a second-line treatment. He had myalgia and a slightly elevated creatinine kinase (CK) on the day of the second administration of pembrolizumab. Five days later, the patient was admitted with severe fatigue and an abnormal gait. Physical examination revealed reduced muscle reflexes and proximal muscle weakness. An electrocardiogram (ECG) demonstrated a wide QRS complex ventricular rhythm. A marked elevation of cardiac enzymes, including CK, myoglobin, and cardiac troponin I, was detected. Myocardial biopsy revealed inflammatory cell infiltration and the partial impairment of myocardial tissue. The electromyogram was normal, but inflammation in myofibers was noted in a muscle biopsy. Myocarditis and myositis as immune-related adverse events (irAEs) were suspected, and the patient began intravenous steroid therapy and plasma exchange. However, the patient underwent cardiac arrest three days after admission and began extracorporeal membrane oxygenation and intra-aortic balloon pumping therapy. Despite steroid pulse therapy, the patient demonstrated no sign of improvement and subsequently died 17 days after admission. Immune-mediated myocarditis is a rare but fatal irAE of an immune checkpoint inhibitor (ICI). The present case suggests that myositis precedes myocarditis. Therefore, if myositis is suspected, subsequent myocarditis may need attention. In conclusion, we found that myositis and myocarditis developed in a patient with advanced urothelial carcinoma after pembrolizumab treatment. A routine follow-up of CK and cardiac troponin I, as well as an ECG, should be performed to identify any possible ICI-induced myocarditis and myositis quickly.

A 69-year-old Japanese woman was admitted to our hospital with progressive muscle weakness and dysphagia. She was taking pitavastatin for dyslipidemia. Her serum creatine kinase was 6,300 U/L. Pitavastatin was stopped, but her symptoms deteriorated, and cardiac congestion appeared. A muscle biopsy showed necrotizing myopathy (NM), and anti-signal recognition particle (SRP) antibody was positive. 18F-fluorodeoxyglucose-positron emission tomography showed an abnormal uptake, and magnetic resonance imaging showed abnormal gadolinium enhancement in the left ventricular wall. An endomyocardial biopsy revealed inflammatory cardiomyopathy. Steroid, tacrolimus, and intravenous immunoglobulins were effective against the symptoms. This is the first case of biopsy-proven secondary cardiomyopathy due to anti-SRP-positive NM.