# Eculizumab Treatment of Massive Hemolysis Occurring in a Rare Co-Existence of Paroxysmal Nocturnal Hemoglobinuria and Myasthenia Gravis

## TL;DR

A rare case of a patient with both myasthenia gravis and paroxysmal nocturnal hemoglobinuria is described, where eculizumab helped control hemolysis but the patient ultimately died from complications.

## Contribution

This paper reports a rare co-occurrence of MG and PNH and demonstrates the use of eculizumab in managing hemolysis in this unique clinical scenario.

## Key findings

- Eculizumab effectively controlled massive hemolysis in a patient with PNH and MG.
- The patient experienced temporary improvement after eculizumab treatment but later succumbed to respiratory failure and sepsis.
- The case highlights the shared immune-mediated mechanisms involving the complement system in both diseases.

## Abstract

The co-occurrence of myasthenia gravis (MG) and paroxysmal nocturnal hemoglobinuria (PNH) is rare; only one case has been published so far. We report a 63-year-old Caucasian female patient who was diagnosed with MG at the age of 43. Thymoma was also detected, and so it was surgically resected, which resulted in reasonable disease control for nearly 20 years. Slight hemolysis began to emerge, and then myasthenia symptoms progressed, so immunosuppressive therapy was started. Due to progressive disease and respiratory failure, the patient underwent plasmapheresis, and ventilatory support was stopped. Marked hemolysis was present, and diagnostic tests confirmed PNH with type III PNH cells. Her myasthenia symptoms aggravated, mechanical ventilation had to be started again, and due to the respiratory acidosis, massive hemolysis occurred. After two plasmapheresis sessions, the patient received eculizumab at 600 mg, resulting in prompt hemolysis control. After the second dose of the treatment, the patient was extubated. Still, due to their inability to cough, she developed another respiratory failure and pneumonia–sepsis, resulting in the patient’s death. This case highlights the rare association between these two serious diseases and similar immune-mediated pathophysiology mechanisms involving the complement system.