Dermatomyositis (DM) is an autoimmune myopathy of unknown aetiology and involves the development of characteristic skin manifestations, muscle weakness, and internal organ involvement. Recently, several myositis-specific autoantibodies, the marker antibodies (Ab) for specific clinical manifestations, have been measured by clinical laboratory investigations, and may possibly be used for predicting DM prognosis. The anti-NXP-2 (also known as anti-MJ) Ab has been identified as a myositis-specific autoantibody for juvenile DM with cutaneous calcinosis and severe muscle weakness;1 however, the clinical manifestations and organ involvement, such as internal malignancy and interstitial lung disease in adult DM patients with anti-NXP-2 Ab, are still unclear. Very recently, close associations between anti-NXP-2 Ab and severe dysphagia in two USA cohorts of adult DM patients were reported.2,3 Here, we report three successfully treated cases of anti-NXP-2 Ab-positive DM with dysphagia using intensive immunosuppressive therapies, including corticosteroid pulse therapy, tacrolimus (FK506), and high-dose intravenous immunoglobulin therapy (IVIg).
CASE 1
A 55-year-old Japanese male developed severe dysphagia with thrombocytopenia (16 x109 /L) and severe generalised subcutaneous oedema on the extremities during the initial treatment for DM with 1 mg/kg/day prednisolone (PSL). Methylprednisolone pulse therapy (1 g/day for 3 days) and IVIg (400 mg/kg/day for 5 days) with platelet transfusion was started. The patient’s muscle weakness, thrombocytopenia, and subcutaneous oedema dramatically improved, but the dysphagia did not. Percutaneous endoscopic gastrostomy tube insertion was required for the dysphagia with refractory aspiration pneumonia. Dysphagia was not improved with high dose PSL treatment; however, it was successfully treated after eight courses of monthly IVIg and tacrolimus (4 mg/kg/day) and the patient returned to oral feeding.
CASE 2
A 70-year-old Japanese male developed severe dysphagia during the initial PSL treatment (1 mg/kg/day) and required a temporal nasogastric tube for feeding. His dysphagia improved with methylprednisolone pulse therapy and tacrolimus (5 mg/kg/day).
CASE 3
A 25-year-old Japanese female developed mild dysphagia during the tapering of PSL and tacrolimus from initial daily PSL therapy (0.5 mg/kg/day). Her dysphagia improved with methylprednisolone pulse therapy (0.5 g/day for 3 days) and tacrolimus (4 mg/kg/day).
All three of these cases were diagnosed using the Bohan and Peter’s criteria.4 Anti-NXP-2 Ab was measured using the specific enzyme-linked immunosorbent assay (ELISA).5 The presence of dysphagia was diagnosed by use of video fluoroscopic examinations. No internal malignancy or cutaneous calcinosis were detected in any of the three patients. Interstitial lung disease was present in Case 2.
Dysphagia is a serious manifestation of severe DM cases and is associated with a high risk of the patient developing aspiration pneumonia and receiving a poor prognosis.6 Dysphagia develops in 25–84% of adult polymyositis/DM6 patients and in around 30–40% of juvenile DM patients with anti-NXP-2 Ab.1,7 In the Mie University Hospital, Tsu, Japan, we treated 22 Japanese adult cases of DM between January 2014 and March 2017. Three of the 22 (14.3%) cases were anti-NXP-2 Ab positive and developed dysphagia. The anti-NXP-2 Ab positive DM patients developed dysphagia more frequently (62.5% and 70.0%) compared with anti-NXP-2 Ab negative DM patients (35.1% and 38.6%) in two recent USA cohorts of DM patients, respectively.2,3 Measurement of anti-NXP-2 Ab in DM patients has the potential to be used as a predictor of the severe complication of dysphagia and strict control with intensive immunosuppressive therapy, including corticosteroid pulse therapy, calcineurin inhibitors, and IVIg, should be considered for anti-NXP-2 Ab positive DM cases with dysphagia.
