Alemtuzumab‐induced petechiae and epistaxis in a patient with relapsing remitting multiple sclerosis; A case report Farhad Mahmoudi1*, Sayed Ali Emami1, Farid Masaeli1, Najmeh Rayatpisheh21 School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran2School of Medicine, Shahrekord University of Medical Sciences, Shahrekord, IranCorresponding author*Farhad MahmoudiSchool of Medicine,Isfahan University of Medical Sciences,Isfahan, IranEmail: farhad.mg116@gmail.comAbstract: This case report presents a 58-year-old woman with Multiple Sclerosis (MS) who developed petechiae and epistaxis, rare side effects following Alemtuzumab treatment. While these reactions are infrequent, heightened awareness among healthcare providers is essential as Alemtuzumab gains popularity in MS treatment. Recognizing and managing such hypersensitivity reactions promptly is crucial for improved patient care. 1.Introduction Multiple Sclerosis (MS) is an autoimmune disease that affects the central nervous system. The course of the disease varies among individuals, leading to a wide range of symptoms and patterns of presentation. Additionally, there are other conditions, such as radiologically isolated syndrome, which can progress to MS(1). While there is no curative therapy for this condition, certain drugs can modify the course of the disease and improve the prognosis and quality of life for patients.Disease-modifying treatments (DMTs) are the preferred treatment option for patients with MS. Alemtuzumab is an intravenously administered DMT drug that has been available since 2014 for the treatment of patients with multiple sclerosis who have not responded adequately to two or more DMTs. It is a recombinant DNA-derived humanized monoclonal antibody that selectively binds to the CD52 antigen on B and T lymphocytes, depleting them from the bloodstream. This drug has been described as a safe and effective treatment with minimal side effects for patients with relapsing-remitting multiple sclerosis.(2)While there are few studies on the cutaneous adverse effects of Alemtuzumab, in this study, we report the first case of an MS patient treated with Alemtuzumab who developed drug-induced petechiae and epistaxis.2. Case presentationA 58-year-old Caucasian woman with relapsing-remitting multiple sclerosis, who had no previous medical conditions, presented to the emergency department due to muscle spasms and stiffness in her right foot. Neurological examination revealed weakness in her right lower limb with 3/5 muscle strength. She was diagnosed with MS at the age of 26 through an MRI and had previously been on weekly Interferon-beta (IFNb) treatment. During acute MS attacks, she received intravenous corticosteroids. Despite being on disease-modifying therapies (DMTs), she experienced more relapses in the last year, and her Expanded Disability Status Scale (EDSS) was 3. During the current hospitalization, the patient underwent brain and cervical spinal MRI, which revealed the appearance of new periventricular white active plaques in addition to previous black old lesions.Considering the progression of her disease condition, she was started on treatment with Alemtuzumab at a dose of 12mg/day IV. There were no drug reactions, and after completing the treatment, her muscle spasms and stiffness resolved, and the patient was discharged from the hospital.The day after, the patient came to the hospital to receive the second dose of the drug. While receiving the treatment, her condition remained stable, and she did not experience any notable symptoms. However, one day after finishing the first dose, the patient started to experience a gradual appearance of petechiae on her upper and lower limbs, chest, shoulders, and back. Moreover, a few minutes later, she developed epistaxis. Her blood pressure and heart rate were 127/73 and 87, respectively. The patient denied any previous history of eczema, skin issues, or respiratory allergies.Dermatology was consulted to investigate the possible causes of petechiae, and ENT was consulted to manage and evaluate the epistaxis. Despite applying pressure to the nostrils and placing ice on the forehead, the epistaxis did not cease. Consequently, the patient underwent posterior nasal packing, which successfully halted the bleeding.