Isolated Neck Extensor Myositis and Chest Wall Skin Thickening: Case Report of a Rare Initial Presentation of Systemic Sclerosis and Overlap Myositis

Background Systemic sclerosis is a multisystemic connective tissue characterized by immune dysregulation, fibrosis and vasculopathy. Skin thickening, a cardinal feature of this disease process, characteristically progresses in a centripetal pattern.[1] Overlap disease with idiopathic inflammatory myositis can be seen, classically involving weakness of the proximal muscle groups of the upper and lower limbs.[2]

Case Report We report the case of a 46-year-old female referred for assessment of possible systemic sclerosis with a several month history of neck extensor weakness, Raynaud’s phenomenon, moderate skin thickening isolated to the chest, positive ANA 1:640 nucleolar, and elevated CK of 436. Over the next few months, she developed rapidly progressive and severe skin thickening of the proximal and distal extremities, face and hands with associated sclerodactyly. Advanced serological testing was negative for myositis or systemic sclerosis associated with autoantibodies. Baseline investigations including echocardiogram, pulmonary function test and high-resolution CT scan of the lungs were normal. MRI of the extremities and neck demonstrated mild edema to the posterior neck paraspinal muscles, EMG of the neck extensors was positive for irritable myopathy, and subsequent muscle biopsy of the cervical paraspinal muscles demonstrated marked fibrosis with end-stage muscle atrophy in keeping with partially treated myositis. Punch biopsies of the skin demonstrated sclerosing dermatitis. A diagnosis of diffuse cutaneous systemic sclerosis with overlap myositis was made. She was treated initially with methotrexate followed by mycophenolate, however due to rapidly progressive cutaneous disease she underwent autologous hematopoietic stem cell transplant approximately 8 months after initial presentation. With ongoing follow-up 6 months post-transplant, the patients’ skin thickening had significantly improved, her myositis and Raynaud’s phenomenon had resolved, and she remained in remission off all immunosuppressive therapies.

Conclusion Isolated neck extensor myositis and initial skin thickening of the chest is a rare presentation of early diffuse cutaneous systemic sclerosis. This case highlights the importance of close follow up of patients with atypical disease manifestations and seeking histopathological correlation to assist in making a definitive diagnosis.

References [1.] Volkmann E. Lancet 2022;401:304-18. [2.] Bhansing K. Arthritis Res Ther 2014;16:R111.