An 80-year-old man, Mr. Van, who suffered from a severe, refractory autoimmune condition known as immune-mediated necrotizing myopathy (IMNM), has shown significant improvement after receiving treatment with a biologic drug. His symptoms, which began one year ago, included difficulty climbing stairs and raising his arms, despite no joint pain. His limb weakness progressively worsened, making daily activities and movement challenging.

Upon his admission to Tam Anh General Hospital Hanoi, Mr. Van exhibited proximal muscle weakness, an inability to stand independently, reduced thigh muscle strength, and shortness of breath upon exertion. Blood tests revealed his CK muscle enzyme level was over 7,000 U/L, more than 35 times the normal range. He tested positive for the specific anti-SRP antibody, leading to a thigh muscle biopsy.

Associate Professor, Doctor Dang Hong Hoa, Head of the Department of Musculoskeletal, diagnosed Mr. Van with IMNM. This autoimmune myositis subtype lacks a specific cure and is typically managed initially with anti-inflammatory and immunosuppressive drugs. Associate Professor Hoa highlighted the rapid progression and severe prognosis of Mr. Van's condition, noting the potential for loss of mobility within weeks to months. The disease can lead to serious complications, including respiratory paralysis from attacks on the diaphragm and intercostal muscles, difficulty swallowing due to pharyngeal muscle involvement, and heart failure if the heart muscle is affected.

Initially, Mr. Van received treatment with slow-acting anti-inflammatory and immunomodulatory drugs. However, he only responded during the initial phase before his condition became refractory. Following an inter-departmental medical consultation, doctors decided to change the treatment regimen, opting for the biologic drug Rituximab.

Associate Professor Hoa explained that Rituximab specifically targets B cells to reduce the production of anti-SRP antibodies, thereby halting the muscle necrosis process. This selective action directly addresses the underlying mechanism of immune-mediated necrotizing myopathy. However, due to its potent immunosuppressive effects, the drug carries an increased risk of opportunistic infections and the potential reactivation of latent diseases.

Given these risks, Mr. Van underwent thorough pre-treatment screening, including checks for latent tuberculosis, hepatitis B and C virus, blood and urine tests, and assessments of lung, liver, and kidney function. After the drug infusion, medical staff closely monitored the patient to immediately manage any opportunistic infections if they occurred. He was only discharged once his condition stabilized.

Mr. Van continued anti-inflammatory medication at home. Thanks to the biologic drug's effectiveness, he was able to gradually reduce his corticosteroid dose, mitigating side effects such as Cushing's syndrome, risk of osteoporosis, adrenal insufficiency, and hypertension. At his three-month follow-up appointment, his CK muscle enzyme level had decreased to 200 U/L, near the normal range. He no longer experienced shortness of breath, and his limb movement and muscle strength significantly improved.

Family members encouraging Mr. Van during treatment. Photo: Tam Anh General Hospital

Associate Professor Hoa cautioned that autoimmune myositis often progresses subtly and can be mistaken for common musculoskeletal disorders in older adults. Early signs include difficulty climbing stairs, stepping onto high surfaces, raising arms, lifting objects, combing hair, or standing up from a seated position. The disease may also be associated with prolonged statin use and, in some cases, accompanies malignancy. Early medical examination is crucial for timely diagnosis and treatment.

Currently, biologic drugs utilizing monoclonal antibodies are available. These drugs target specific disease mechanisms, helping to control autoimmune musculoskeletal diseases, even in refractory cases. Patients should seek examination and treatment at medical facilities according to personalized regimens and must not arbitrarily stop or reduce medication doses to prevent disease recurrence or worsening.

Thanh Long

*Patient's name has been changed