Painful purple nodule on the right thigh—Answer

Glomus tumors are neoplasms of the normal glomus body. This structure is a neuromyoarterial body composed of an afferent arteriole and an efferent venule with multiple interconnections. Contractility of glomus cells occurs after temperature changes are sensed by nerves within the glomus body, hence its importance in local blood flow regulation [1,2]. Glomus tumors are rare corresponding to 1,6% of all soft tissue tumors. They are usually solitary, presenting as a blue to pink, soft nodule associated with a classic triad of symptoms: pain, pinpoint tenderness and cold sensitivity. These tumors are frequently located on the extremities, mostly in the subungueal areas of the digits. Extradigital locations include upper and lower extremities, trunk and less commonly the face. Therefore, glomus tumors in extradigital locations may represent a diagnostic challenge resulting in misdiagnosis of these lesions [3,4]. Dermoscopy features of extradigital glomus tumors have rarely been documented [5]. In our case, central purple homogeneous area correlates to enlarged vessels and surrounding white patch probably corresponds to fibrous structures. While not specific, theses findings may represent an additional clue to complement the difficult diagnosis of glomus tumors in a less common location. Accurate diagnosis of extradigital glomus tumors is important to avoid long diagnostic delays, providing an early adequate surgical treatment and diminishing associated local chronic pain.