Fatal and extensive multiorgan hemorrhages in anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis: An autopsy case report

A Case of Hemorrhagic Myositis Associated With Prophylactic Heparin Use in Dermatomyositis

Dermatomyositis (DM) is a rare systemic autoimmune disease that is associated with inflammation of the skin and muscles. It typically presents with weakness of the proximal muscles along with characteristic skin lesions such as Gottron's papules and heliotrope rash. One of the most feared complications of this disease is the appearance of spontaneous hemorrhagic myositis, as most reported cases are fatal. The mechanism or risk factors of this condition have not been elucidated; however, prophylactic anticoagulation has been correlated with it in previous case reports, although idiopathic hemorrhagic myositis may also be present. We present a case of spontaneous intramuscular hemorrhage (SIH) in a recently diagnosed DM patient. A 59-year-old Hispanic male with a medical history of recently diagnosed prostate cancer and DM presented to the emergency department (ED) due to worsening anemia. His previous hemoglobin (Hgb) was 9 g/dl, but repeated laboratory tests revealed a level of 6.5 g/dl and later 5.5 g/dl at the ED. On admission, the patient was afebrile, tachycardic, and normotensive, with no overt sign of gastrointestinal bleeding. The physical exam revealed an ecchymosis on the right medial aspect of the thigh, and a digital rectal exam was negative. Computer tomography (CT) of the abdomen and pelvis without contrast was ordered due to suspicion of a retroperitoneal hematoma, revealing an interval development of a right groin complex fluid collection of up to 6 cm, concerning a possible hematoma. The patient did not have any previous vascular procedures in the area but was exposed to deep vein thrombosis (DVT) prophylaxis during the previous admission. Vascular surgery was consulted, and the recommendation was made to proceed with conservative management. On the third day, the patient developed new-onset, left-sided pleuritic chest pain. Upon examination, significant swelling and tenderness were noted in his left pectoral region, which was not present on admission. A CT chest without contrast was ordered due to concerns of underlying hematomas, revealing bilateral thickening of the pectoralis muscles, more on the right side, with a fluid collection of 2.5 cm × 1.3 cm. In addition, there was thickening of the right lateral chest wall muscles in the posterior right trapezius or supraspinatus muscles, most likely from intramuscular hemorrhage. The patient was transferred to the step-down unit for close monitoring. Conservative management was continued with as-needed transfusions for three days until hemoglobin stabilized at 9.8 mg/dL. Once stable, the patient was resumed on steroids and immunosuppressive therapy with posterior resolution of the SIH. SIH has been reported in DM, particularly more prominent in those with anti-MDA-5 antibodies. A case series and literature review showed 60.9% mortality within six months in those presenting with SIH, with a poorer prognosis (80% mortality) in those with deep muscle bleeding versus superficial (25%). There is currently no consensus on the treatment approach, and arterial embolization has not been proven effective. In our patient, conservative management with close surveillance and frequent transfusions helped achieve hemodynamic stability. Clinicians should be more aware of these rare but life-threatening complications in patients presenting with DM.

Friend or foe: RIG- I like receptors and diseases

Retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), which are pivotal sensors of RNA virus invasions, mediate the transcriptional induction of genes encoding type I interferons (IFNs) and proinflammatory cytokines, successfully establishing host antiviral immune response. A few excellent reviews have elaborated on the structural biology of RLRs and the antiviral mechanisms of RLR activation. In this review, we give a basic understanding of RLR biology and summarize recent findings of how RLR signaling cascade is strictly controlled by host regulatory mechanisms, which include RLR-interacting proteins, post-translational modifications and microRNAs (miRNAs). Furthermore, we pay particular attention to the relationship between RLRs and diseases, especially how RLRs participate in SARS-CoV-2, malaria or bacterial infections, how single-nucleotide polymorphisms (SNPs) or mutations in RLRs and antibodies against RLRs lead to autoinflammatory diseases and autoimmune diseases, and how RLRs are involved in anti-tumor immunity. These findings will provide insights and guidance for antiviral and immunomodulatory therapies targeting RLRs.

Differentiation of idiopathic pulmonary hemosiderosis from rheumatologic and autoimmune diseases causing diffuse alveolar hemorrhage: establishing a diagnostic approach

This narrative review provides an overview of diffuse alveolar hemorrhage (DAH) associated with rheumatologic and autoimmune diseases and their differentiation from idiopathic pulmonary hemosiderosis (IPH). Relevant immunologic diseases associated with DAH are discussed, and a diagnostic flowchart is proposed to establish a "definitive" diagnosis of IPH within the spectrum of DAH. IPH is a rare cause of recurrent DAH both in children and adults. In adults, a definitive diagnosis of IPH requires a lung biopsy and histopathologic examination demonstrating intraalveolar hemorrhage, hemosiderin-laden macrophages, and a variable degree of fibrosis in the absence of both capillaritis and cellular inflammation. The presence of small vessel vasculitis points towards immunologic, well-differentiated, or sometimes undifferentiated rheumatologic diseases. However, it is essential to recognize that many rheumatologic diseases may in the initial phase present with DAH without any evidence of capillaritis, thus mimicking IPH. Although not definitely established, it is likely that immunologic processes are involved in IPH, and we, therefore, suggest the consideration of a more suitable term for the disease, e.g., "Immune-mediated Pulmonary Hemosiderosis" to acknowledge the aberrancy in the immune parameters and a positive response to immunosuppressive therapy.

Rapidly Progressive Interstitial Lung Disease Associated with Melanoma Differentiation-Associated Gene 5 Antibody

Anti-melanoma differentiation-associated gene-5 (MDA-5) antibody is an autoantibody found in patients with dermatomyositis. These antibody-positive patients are clinically characterized by complications of rapidly progressive interstitial pneumonia resistant to treatment and with poor prognosis. We describe herein a patient with MDA-5 antibody-positive interstitial lung disease, which progressed rapidly to death after a period of slow progress. Recently, attention has been paid to the similarities in clinical courses and CT images between MDA-5 antibody-positive interstitial lung disease and coronavirus disease 2019 (COVID-19)-associated pneumonia. Patients with MDA-5 antibody do not always have diffuse and evenly distributed bilateral opacities at the time of first presentation. This patient had significant laterality of such opacities. It should be considered that MDA-5 antibody-positive patients with such laterality in opacities might progress rapidly. Chest physicians, dermatologists, and dermatologists need to be aware of the characteristics of the disease for optimal treatment choices.

Dermatomyositis With Anti-MDA5 Antibodies: Bioclinical Features, Pathogenesis and Emerging Therapies

Anti-MDA5 dermatomyositis is a rare systemic autoimmune disease, historically described in Japanese patients with clinically amyopathic dermatomyositis and life-threatening rapidly progressive interstitial lung disease. Subsequently, the complete clinical spectrum of the disease was enriched by skin, articular and vascular manifestations. Depending on the predominance of these symptoms, three distinct clinical phenotypes with different prognosis are now defined. To date, the only known molecular component shared by the three entities are specific antibodies targeting MDA5, a cytosolic protein essential for antiviral host immune responses. Several biological tools have emerged to detect these antibodies, with drawbacks and limitations for each of them. However, the identification of this highly specific serological marker of the disease raises the question of its role in the pathogenesis. Although current knowledge on the pathogenic mechanisms that take place in the disease are still in their enfancy, several lines of evidence support a central role of interferon-mediated vasculopathy in the development of skin and lung lesions, as well as a possible pathogenic involvement of anti-MDA5 antibodies. Here, we review the clinical and biological evidences in favor of these hypothesis, and we discuss the contribution of emerging therapies that shed some light on the pathogenesis of the disease.

Slowly progressive interstitial lung disease preceding typical dermatomyositis symptoms in anti-melanoma differentiation-associated gene 5 antibody-positive clinically amyopathic dermatomyositis

A 73-year-old woman who visited our hospital complaining of dry cough for three months was refractory to antimicrobial therapy. Chest computed tomography revealed subpleural consolidation. Specimens obtained from surgical lung biopsy revealed subpleural perilobular airspace organization and fibrosis. After the biopsy, mechanic's hand and Gottron's papules appeared, and anti-melanoma differentiation-associated gene 5 (MDA5) antibody was found to be positive. Subsequently, anti-MDA5 antibody measured in cryopreserved serum from her first admission proved to be positive. It is difficult to suspect the presence of anti-MDA-5 antibody in patients with interstitial lung disease without typical dermatomyositis symptoms or slow disease progression.