Antinuclear Antibody (ANA) and Anti-Mi-2-Alpha Positive Dermatomyositis Hinting a Cancer Diagnosis

Abstract

Dermatomyositis (DM) is a relatively uncommon inflammatory myopathy that has been linked to cancer. We report the case of an 81-year-old woman with cecum adenocarcinoma presenting with antinuclear antibody (ANA) and anti-Mi-2-alpha antibody-positive DM. The patient complained of anorexia, symmetric proximal muscle weakness and skin rash and presented with elevated muscle enzymes. A skin and muscle biopsy supported the diagnosis of DM as did the limbs magnetic resonance imaging (MRI) and electromyography. A diagnosis of localized adenocarcinoma of the cecum was made through colonoscopy and the patient was successfully surgically managed, with decreasing muscle enzymes at discharge and gradual recovery of muscle strength. The presence of both ANA and anti-Mi-2 autoantibodies has classically been described as comprising a better prognosis with a lower risk of underlying malignancy. This case highlights the importance of pursuing a cancer diagnosis in elderly patients presenting with DM even in presence of less predisposing immunological profiles.

Keywords: adult onset; anti-mi2 alpha; antinuclear antibody; cancer; dermatomyositis.

Figure 1. Dermatomyositis skin rash

(a) V-sign and heliotrope/facial erythema that involves nasolabial folds. (b) Gottron sign: extensor surface of the elbow presenting erythematous and scaling plaques. (c) Facial erythema that involves nasolabial folds. (d) Gottron sign: erythematous patches on the extensor surfaces of the joints of the hands with periungual erythema.

Figure 2. MRI - T2-weighted images presenting hyperintense signal throughout the affected muscles and peri-muscular oedema

(a) Periscapular muscles in coronal view. (b) Thigh muscles in sagittal view. (c) Hip muscles in coronal view - gluteal aspect. (d) Thigh muscles in axial view.