Invasive Non-groupable Meningococcal Disease Complicated by Brain Abscess Revealing C6 Complement Deficiency in a Young Adult

. His course was complicated by consumptive coagulopathy, stress-induced cardiomyopathy, and a 2.8×1.2 cm rim-enhancing brain lesion concerning for abscess. Transesophageal echocardiography showed no endocarditis, supporting hematogenous seeding. The abscess resolved with prolonged intravenous ceftriaxone. Outpatient immunologic evaluation revealed low CH50 and C6 complement deficiency, prompting vaccinations and long-term penicillin prophylaxis. This case highlights brain abscess as a rare complication of meningococcal disease and underscores the importance of evaluating for complement deficiency in atypical presentations.