553P Brachio-cervical inflammatory myopathy, an unknown disease with diverse serological and histopathological findings and poor response to treatment

• Published in: Neuromuscular disorders : NMD Vol. 43; p. 104441
• Main Authors: Garcia, S. Kapetanovic, Jimenez-Almonacid, J., Toldos-Gonzalez, O., Ruiz-Lucea, E., Rodrigo-Armenteros, P., Hernandez-Lain, A., Dominguez-Gonzalez, C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2024
• ISSN: 0960-8966
• DOI: 10.1016/j.nmd.2024.07.153

This study aims to characterize a cohort of patients diagnosed with brachio-cervical inflammatory myopathy (BCIM), emphasizing serological and histopathological characteristics, as well as the diverse responses observed with treatment interventions. Epidemiological, clinical, laboratory and histopathological findings of patients referred to 2 Neuromuscular Units in Spain from 2010 to 2024. 7 patients, all females with a mean age of 56 years (37-77) presented with weakness in facial, cervical, proximal upper limbs and paraspinal muscles. The age of onset ranged from 31-67 years with a subacute phase of deterioration (several months in 5/7) and a large period of stabilisation. Distal upper limbs and proximal lower limbs involvement was less frequent, milder and later in the disease without loss of ambulation. Asymmetric phenotypes were rare. 4/7 suffered esophagic dysphagia (1 patient needed gastrostomy tube). Respiratory insufficiency was less frequent and only 3 patients used non-invasive mechanical ventilatory support because of diaphragmatic weakness and nocturnal hypoventilation; only 1 patient associated lung inflammatory disease. Scleroderma and other systemic features diseases such as Raynaud syndrome were frequent but mild and could not be detected in general practice. The immunological profile was heterogeneous and erratic. 5/7 patients have ANA, anti-Ku, anti-RNP, anti-Ro52 or anti-PmScl75 positive antibodies without a clear pathogenic relation. Muscle MRI was helpful as a support of focal inflammatory disease because 6/7 patients showed hyperintense signal in STIR sequences in periscapular or cervical muscles and no involvement of lower limbs. Muscle histopathological findings were heterogeneous with variable degrees of inflammation but not constant and 3/7 had a more dystrophic pattern probably related to the long delay between the onset and the biopsy time. Endomysial lymphocyte infiltrates and increased MHC-I expression were the most frequent and helpful findings. MAC deposition was rare. The most severe cases showed variable degrees of necrosis and some IBM-like features as sarcoplasmic inclusions and rimmed vacuoles. We performed NGS studies in all cases that did not detect any pathological variant in genes related to muscle dystrophy. The response to immunosuppressive therapy was partial and irregular, with CPK level improvement but stabilization of muscle weakness, and severe periscapular and paraspinal progressive muscle atrophy. 3/7 patients are currently receiving no treatment and remain stable. BCIM a rare muscle inflammatory disorder, can sometimes be mistaken for muscular dystrophies. Enhanced diagnostic and prognostic methodologies necessitate the identification of an immunological biomarker and a deeper understanding of its pathophysiology. Currently, standard immunosuppressive treatments yield limited responses with potential secondary adverse effects.