Amyopathic dermatomyositis (ADM) is a clinical subtype of dermatomyositis, which can be associated with malignancy and lung disease. We report a retrospective review of 21 cases of ADM presenting to a tertiary clinic. We discuss the clinical presentations, investigation, and cancer and lung associations. Patients were included if they met the European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) criteria for ADM. We identified 21 patients with ADM (16 women and five men). Mean age at diagnosis was 61 years (range 35–81). Clinical features were as follows: Gottron papules (n = 15; 71%), nailfold involvement (n = 16; 76%), heliotrope rash (n = 12; 57%), shawl sign (n = 11; 52%), Raynaud phenomenon (n = 9; 43%), scalp disease (n = 6; 29%) and calcinosis (n = 3; 14%). Antinuclear antibody (ANA) was positive in 76% of patients (n = 16) and 41% (n = 9) had myositis-specific antibodies. Four patients had a prediagnosed malignancy. One patient had prostate cancer detected on malignancy screen. One nerve sheath tumour was diagnosed within 1 year of ADM diagnosis and one cholangiocarcinoma within 3 years. Three patients were found to have mild lung fibrosis, but none was found to have severe interstitial lung disease. Patients were treated with corticosteroids (n = 16), hydroxychloroquine (n = 11), methotrexate (n = 10), mycophenolate (n = 6), cyclophosphamide (n = 3), rituximab (n = 3), intravenous immunoglobulin (n = 3), mepacrine (n = 2), azathioprine (n = 1), ciclosporin (n = 1) and thalidomide (n = 1). In conclusion, in our study, a female preponderance and cutaneous findings involving extremities were seen in the majority of patients (95%), in keeping with other published data (el-Azhary RA, Pakzad SY. Amyopathic dermatomyositis: retrospective review of 37 cases. J Am Acad Dermatol 2002; 46:560–5). Our study further highlights the heterogeneity of cutaneous clinical presentation of ADM, which is broadly consistent with other reported cohorts [el-Azhary and Pakzad; Tang K, Zhang H, Jin H. Clinical characteristics and management of patients with clinical amyopathic dermatomyositis: a retrospective study of 64 patients at a tertiary dermatology department. Front Med (Lausanne) 2021; 8:783416]. We report high levels of hand and nail involvement, emphasizing the need for formal assessment of hands, including dermoscopy of nails. ANA was positive in 76% of patients; other reported data suggest that it is positive in 31.6–71% (el-Azhary and Pakzad; Tang et al.). Although previous studies have found myositis-specific antibodies in 87.5% (Tang et al.), only 42% in our cohort had positive antibodies; therefore, a high index of suspicion is required to detect cases and appropriately screen for associated morbidity (lung disease and malignancy). In addition, a third of patients had associated malignancy prediagnosed or within 3 years of diagnosis, highlighting the importance of baseline screening and ongoing follow-up.
