Case series of extradigital glomus tumors: imaging findings, differential diagnosis and radiologic–pathologic correlation.

Background: Glomus tumors are benign mesenchymal tumors of the neuromyoarterial glomus bodies. They are generally localized at the subungual area of the fingers. Extradigital or non-subungual glomus tumors are less common. Their diagnosis can be challenging because of their lower incidence, nonspecific symptoms, and the fact that they can be missed during the physical examination. The aim of this case series is to provide an overview of non-subungual glomus tumors, including the patients' epidemiology characteristics, tumor localization and size, their varied imaging manifestations in ultrasound and magnetic resonance imaging, differential diagnosis and histopathological features. Our report included 64 patients with the diagnosis of non-subungual glomus tumor in the Pathology Department at the La Paz University Hospital in Madrid from January 1966 to September 2022. There were 44 men and 20 women (mean age, 55.8 years; range, 8–85 years). The tumors had a mean size of 1 cm and were located in the lower limbs in most cases (59.3%). In 17 cases (27%) a diagnostic imaging test was performed (US, MRI or both). The radiological appearance of a glomus tumor on ultrasound was in most cases a circumscribed hypoechoic oval nodule located in the subcutaneous layer. Spectral Doppler can demonstrate both venous and arterial intralesional flow and in some cases a "Vascular stalk sign,'' seen in 4/9 cases. MRI assists in providing a more detailed characterization of these lesions, which present as T2-weighted hyperintense nodules with avid enhancement. Short conclusion: Glomus tumors are considered rare neoplasms, accounting for a small percentage of all tumors. Our report brings together the most up-to-date information available regarding the imaging findings and differential diagnosis of this entity. Although ultrasound images are not specific, they are crucial for early diagnosis, provide precise location information, and serve as a guide for tumor excision. MRI study helps to better characterize these tumors. The diagnosis is mostly clinical, with confirmation in the histopathologic study. [ABSTRACT FROM AUTHOR]