Arthralgia is the most frequent complaint concerning the musculoskeletal system during the developmental age. The main cause of the reported complaints concerning the musculoskeletal system at that age are contusions and then inflammations. The less common causes are benign or malignant bone and soft tissue tumours. Mucous cysts (ganglions) are common pathological changes within the musculoskeletal system. Due to the pathomechanism, a ganglion may occur at any site. The most common locations of ganglions are the joints of the wrist, digits of the hand, of the dorsum of the foot and of the ankle. Ganglions only sporadically cause severe pains or functional impairments of the involved joints. In this paper, we will present a case of a teenager with severe pains and locomotion impairment caused by the presence of the mucous cyst in an atypical localisation in the hip-joint
