Dermatomyositis as Interval Manifestation of Underlying Rectal Cancer Progression: a Case Report and Brief Subject Review

Dermatomyositis is an inflammatory myositis with a constellation of manifestations including characteristic cutaneous rash and myopathy. While the association between dermatomyositis and malignancy has been described, its occurrence as an interval manifestation of underlying rectal carcinoma progression is rare and has not been reported in the literature. We report a case of a 58-year-old gentleman who declined surgical treatment for early rectal cancer and represented a year later with antibody T1F1-γ-associated dermatomyositis with cutaneous manifestations, proximal myopathy and severe dysphagia. A 58-year-old male who initially presented with change in bowel habits and was investigated and diagnosed with early stage rectal cancer declined surgical treatment and follow-up. The patient did not display any signs and/or symptoms of dermatomyositis then. He represented 1 year later with cutaneous manifestations of dermatomyositis, proximal myopathy, and severe dysphagia. Serology was positive for antinuclear antibody and anti-T1F1-γ. Radiological imaging confirmed progression of the tumor to a locally advanced stage involving locoregional nodes (T4N1M0). He underwent long-course neoadjuvant chemoradiotherapy and surgery. Multidisciplinary management with rheumatology was required for intravenous immunoglobulin and steroids for dermatomyositis. The dermatomyositis manifestations displayed progressive regression once steroids were commenced for dermatomyositis, and neoadjuvant therapy was commenced for the rectal malignancy. T1F1-γ-associated dermatomyositis has a strong association with cancer and our case demonstrates the vitality to maintain clinical vigilance and assessment for underlying malignancy. Malignancy-associated dermatomyositis is often steroid responsive and resolves with removal of the underlying tumor. Close multidisciplinary teamwork is important to ensure the best outcomes for the patient.