JAK/IL-6 blockade may control TIF1γ-positive dermatomyositis with macrophage activation syndromeJAK and IL-6 inhibitors help manage severe dermatomyositis complications

Dermatomyositis (DM) is an autoimmune disorder characterized primarily by cutaneous and muscular inflammation. Although the TIF1γ antibody-positive variant frequently correlates with an underlying malignancy, instances of severe multisystem compromise lacking a neoplastic association remain exceptionally uncommon. Macrophage activation syndrome (MAS), a lethal cytokine storm, poses substantial diagnostic and therapeutic challenges in DM. Herein, we detail the case of a young man with TIF1γ-positive DM who initially presented with pyrexia, a characteristic exanthema, and myalgia, and then developed rare multisystem complications. Cardiac manifestations, including pericardial effusion and markedly elevated cardiac enzymes, and gastrointestinal complications, including pneumatosis intestinalis and abdominal wall subcutaneous emphysema, were followed by possible MAS, evidenced by sustained high fever and marked increases in inflammatory indices, specifically serum ferritin and interleukin-6 (IL-6). Recognizing the cytokine storm early, the clinical team used alternative diagnostic criteria rather than relying strictly on the HLH-2004 criteria and initiated immediate JAK/IL-6 blockade. Through dynamic surveillance of inflammatory markers, immunosuppressive regimens were meticulously titrated, culminating in successful disease control and a favorable outcome. This case underscores the rarity of simultaneous cardiac and gastrointestinal involvement in TIF1γ-positive DM in the absence of prior immune checkpoint inhibitor exposure. Furthermore, it emphasizes the need for clinical vigilance regarding MAS even when full diagnostic thresholds are not met. The case also highlights the need for vigilant tumor screening and proactive infection surveillance in anti-TIF1γ-positive DM.