Neurothekeoma in the Axilla Causing Persistent Shoulder Pain: Case Report

Neurothekeomas, also known as neural sheath myxomas, are rare benign tumors of the neural sheath affecting most commonly the head, arms and shoulder of women in their 2 (nd) and 3 (rd) decades of life. Due to the low prevalence and undefined clinical picture, they are hardly considered in the initial differential diagnosis of skin tumors. We report the case of a 24 year-old woman who was seen in 2016 reporting > 1 year of moderate pain and limited mobility of her left shoulder. Clinical evaluation revealed restricted mobility of the affected shoulder and nuclear magnetic resonance imaging showed a T2-weighted contrast-enhanced multilobular mass in the quadrilateral area apparently invading the adjacent humeral cortical region. Histopathology of a needle sample material revealed loose fibroconnective tissue with no signs of invasion, mitosis or atypical figures. Successful surgical excision was performed and the diagnosis of neurothekeoma was confirmed after detailed histopathology, including immunohistochemistry. The patient was asymptomatic at 18 months of follow-up, with full recovery of shoulder movement and no signs of relapse.