Tongue myositis in dermatomyositis with anti-PM-Scl 75 antibody: two case reports.

Background: Dermatomyositis (DM) is a heterogeneous disease characterized by skin rash and muscle weakness. Although tongue disorders have been documented in idiopathic inflammatory myopathies (IIM), biopsy-confirmed tongue myositis remains exceedingly rare, and no reports have been published in patients with DM.

Case presentation: This study describes two rare cases of anti-PM-Scl 75 antibody-positive dermatomyositis with tongue involvement and dysphagia. In case 1, muscle weakness and skin rash improved after the initial therapy. However, the patient developed tongue atrophy, severe pharyngeal dysphagia (Functional Oral Intake Scale (FOIS) level = 3) and dysarthria (Frenchay Dysarthria Assessment scale (FDA) score = 13) during the tapering of glucocorticoid. Escalating glucocorticoids and adding rituximab improved her swallowing (FOIS level = 6) and speech (FDA score = 23) function, though a limited improvement of tongue atrophy. Case 2 presented with severe skin rash, muscle weakness and elevated CK levels, accompanied by tongue redness and swelling, mild pharyngeal dysphagia (FOIS level = 5) and dysarthria (FDA score = 20) at disease onset. With the treatment of glucocorticoid, tacrolimus and intravenous immunoglobulin (IVIG), the patient achieved complete remission.

Conclusion: Tongue myositis may occur in DM and could serve as a potential indicator of disease activity. Early recognition may be beneficial and biological agents warrant further investigation in refractory cases.

Clinical trial number: Not applicable.