High-Resolution Ultrasound Diagnosis of a Lateral Elbow Lump: A Ganglion Cyst in an Unexpected Location.

Posterolateral elbow ganglion cysts are extremely rare and have been previously documented almost exclusively on clinical and magnetic resonance imaging reports. Herein, we describe the rare case of a 38-year-old man presenting with an asymptomatic lateral elbow lump. High-resolution ultrasound obtained using high-frequency linear transducers demonstrated a well-defined anechoic cyst with a thin stalk extending toward the articular space, consistent with a posterolateral elbow ganglion. This case underscores the problem-solving role of high-resolution ultrasound in the evaluation of elbow lumps, enabling a prompt and accurate diagnosis of this entity despite its atypical and therefore unexpected location.