Rib Osteoblastoma as a Cause of Neurogenic Thoracic Outlet Syndrome: A Case Report.

BACKGROUND Osteoblastoma is a very rare bone tumor accounting for 1% of all bone tumors. Most of the time it involves the spine and long bones and it involves the ribs very rarely. While osteoblastoma occurrence in the first rib has been reported, causing neurogenic thoracic outlet syndrome (TOS) has never been reported. CASE REPORT A 23-year-old woman presented with a left cervical mass associated with pain and paresthesia in the medial aspect of the left upper extremity and 4th and 5th fingers for the previous 3 months. The patient denied any previous illness or trauma in her history. Physical examination revealed a hard mass in the posterior triangle of the left neck with altered sensation in the left 4th and 5th fingers. The patient was investigated by a chest roentgenogram, nerve conduction study, computer tomography (CT) of the chest, and magnetic resonance image (MRI), as well as incisional biopsy. Although all radiological investigations were suggesting osteochondroma with a differential diagnosis of chondrosarcoma, the incisional biopsy showed osteoblastoma. Radical surgical excision of the lesion followed through a left supraclavicular approach. The patient's preoperative symptoms were relieved completely and there was no recurrence of the tumor at 2 years. CONCLUSIONS Osteoblastoma of the first rib is very rare tumor and to present with TOS is extremely rare. The nonspecific radiological characteristics of the tumor, especially on CT, makes the preoperative certainty of the diagnosis unlikely.