NXP-2 Positive Dermatomyositis: A Unique Clinical Presentation

Abstract

Dermatomyositis (DM), a myopathy associated with inflammation and muscle weakness, has historically been difficult to diagnose. Recently, nuclear matrix protein (NXP-2) antibodies have been described as a myositis-specific antibody that may aid in the diagnostic evaluation. We present the case of a 21-year-old, previously healthy, African American male with DM. He presented to our outpatient clinic with periorbital swelling and a rash, for which he was started on prednisone by an ophthalmologist. Towards the end of the prednisone taper, he began to experience muscle weakness, a worsening rash, and dysphagia to solids with a resultant loss of 60 pounds within a month. He was transferred to a tertiary care hospital where he was further evaluated and ultimately diagnosed with dermatomyositis, supported by skin and muscle biopsies, and was found to be positive for NXP-2. He was given intravenous immunoglobulin (IVIG) and high-dose steroids with improvement.

Figure 1

On physical exam, the patient was found to have a patchy, raised, nonulcerative healing rash with hypopigmentation on bilateral arms and forearms and anterior and lateral thighs, a patch of hyperpigmented rash on chest, and a diffuse rash over abdomen.

Figure 2

(a) CT of the abdomen showing thickening of the bowel wall (red arrow). (b) MRI showing edema of the soft tissue (red arrows).