A diagnostic approach to deltoid muscle masses

Abstract

Introduction. Referred pain along the deltoid muscle is a common presentation of patients with shoulder pathology. Intramuscular lesions involving the deltoid muscle are often identified on routine ultrasound or magnetic resonance imaging of the shoulder. The aim of this retrospective study is to review deltoid lesions identified at our institution and to provide a diagnostic approach to aid their management. Methods. A retrospective study of our orthopaedic oncology database was performed to identify lesions referred to our institution between June 2007 and June 2018. Relevant imaging was reviewed on our picture archiving and communication system (PACS). Patient demographics, anatomical extent and MRI characteristics of the lesions were assessed along with histological correlation. Results. 91 patients were included in the study of which 42 (46%) were male and 49 (54%) were female with an age range of 22-88 years. 8 patients were under 40 years and one low grade fibromyxoid sarcoma was identified in this age group. In the over 40 year cohort, the commonest lesion was a lipoma and malignant lesion was identified in 13 (16%) patients. The vast majority of lesions were confined to a single deltoid muscle compartment. 4 lesions involved more than one compartment, all of which were malignant. Conclusions. Deltoid lesions in patients under 40 years are highly likely to be benign whereas the probability of malignancy increases in patients over 40 years of age. Lesions involving more than one muscle compartment are likely to be malignant.