Rhino-orbito-cerebral Rhizopus delemar infection in a patient with anti-melanoma differentiation-associated-5-positive dermatomyositis diagnosed by metagenomic next-generation sequencing: a case report

Rhino-orbito-cerebral mucormycosis, caused by pathogens such as Rhizopus delemar, is a life-threatening opportunistic infection primarily affecting immunosuppressed individuals. Anti-melanoma differentiation-associated protein 5-positive dermatomyositis (MDA5+ DM) is a distinct subtype of DM associated with interstitial lung disease (ILD) and high mortality. Fungal co-infections in anti-MDA5+ DM, particularly mucormycosis, are rarely reported. We report a case of rhino-orbito-cerebral mucormycosis caused by Rhizopus delemar in a patient with anti-MDA5+ DM. The patient was receiving high-dose glucocorticoids and immunosuppressive therapy for rapidly progressive ILD, and later she developed progressive neurological symptoms, palatal ulceration with black eschar, and periorbital swelling. Metagenomic next-generation sequencing (mNGS) of blood subsequently identified Rhizopus delemar, and the diagnosis was further supported by cerebrospinal fluid mNGS. Antifungal therapy was adjusted promptly after pathogen identification. Despite aggressive treatment, the infection progressed rapidly with central nervous system involvement. This case highlights the heightened susceptibility to invasive mucormycosis in patients with anti-MDA5+ DM, likely exacerbated by immunosuppressive therapy. Early diagnosis using mNGS and prompt initiation of targeted antifungal therapy are critical in managing such co-infections. Clinicians should maintain a high index of suspicion for invasive fungal infections in immunosuppressed anti-MDA5+ DM patients presenting with non-specific neurological or sinus symptoms.