Clinical Images: Epistaxis may be a warning sign of lymphoproliferative disorder during methotrexate treatment for dermatomyositis

The patient, an 80‐year‐old man with a one‐year history of anti‐transcription intermediary factor 1‐γ antibody positive dermatomyositis treated with glucocorticoid and methotrexate (MTX), presented with persistent epistaxis from the left nostril. Computed tomography (CT) revealed (A) new masses in the nasal cavity, nasopharynx, and maxillary sinuses. Endoscopic biopsy revealed (B‐1) atypical lymphoid cell proliferation, (B‐2) CD20 positivity, and (B‐3) high Ki‐67 labeling index (95%), whereas (B‐4) Epstein‐Barr encoding small RNA were negative, consistent with findings of diffuse large B‐cell lymphoma. Due to the possibility of other iatrogenic immunodeficiency‐associated lymphoproliferative disorders (OIIA‐LPD), MTX was discontinued and another CT revealed (C) remarkable shrinkage of the mass lesions. The diagnosis of OIIA‐LPD was made, and MTX remained discontinued thereafter. There was no evidence of recurrence during the six‐month follow‐up. The possibility of OIIA‐LPD developing in the nasal cavity has been reported. ¹ In patients with idiopathic inflammatory myositis, OIIA‐LPD is rare, and OIIA‐LPD in the nasal cavity during the treatment of this condition has not been reported. ² Epistaxis during treatment with MTX should also prompt consideration of OIIA‐LPD in the differential diagnosis.

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