A rare cause of scapular pain.

A 57-year-old male patient presented to an academic sports and spine clinic with acute scapular pain and what he described as “winging” of the scapula. Three weeks before his presentation, increasingly severe pain began to develop through his left shoulder; it radiated down the upper arm, and he had pain along his left ribcage. At the same time, a significant prominence of his left scapula abruptly developed. He experienced pain when leaning on the area and upon moving the extremity, and he felt weak when lifting objects. He denied numbness or any symptoms in his other extremities. He reported a previous history of chronic neck issues and an electrocution injury involving his cervical region and left arm that resulted in persisting upper back pain radiating down his left arm and intermittent tingling in the ring and long fingers; however, these symptoms were described as distinctly different and far milder than his presenting complaints. He had no other significant medical history other than a 30-pack-year smoking history. Upon examination, the patient appeared well and was in no apparent distress. The left scapular region protruded from the chest wall at rest (Figure 1). Palpation revealed a nontender prominence following the course of the scapula, but palpation of the scapular borders was difficult. Mild tenderness to palpation at the left lateral rib cage adjacent to the lower scapula was noted. His scapula did not wing further with resisted scapular protraction or a wall push-up. He had weak shoulder external rotation and shoulder abduction to a lesser degree with minimal pain. The results of a cervical spine examination and the remainder of the neurologic examination were normal. A workup was completed, including the images provided, magnetic resonance imaging, and computed tomography angiography (Figures 2 and 3, respectively), and open biopsy pathology results confirmed pleomorphic spindle cell sarcoma with evidence of myofibroblastic differentiation, high grade (Figure 4). Soft-tissue sarcomas (STS) are the most frequent sarcomas identified, with an incidence of 10,660 cases reported in the United States in 2009. They most commonly occur in the extremities (60%). At least 50 different histologic subtypes of STS exist; pleomorphic sarcoma (malignant fibrous histiocytoma) is one of the most common, with a predilection for the shoulder/shoulder girdle [1,2]. Surgery is the standard primary treatment for most sarcomas. Limb-sparing surgery is recommended for extremity STS to achieve local tumor control with minimal morbidity [1]. High-grade extremity sarcomas are at high risk for local recurrence and metastasis, and thus many patients are treated with radiation therapy and chemotherapy preoperatively or postoperatively [1,2]. Factors associated with decreased overall survival and local recurrence in patients are tumor characteristics, including stage, grade, size, depth, and anatomic location [3]. In a Mayo clinic study of 248 cases of intermediateor high-grade surgically treated STS of the extremities diagnosed between 1995 and 2008, the 5-year incidence of local recurrence was 4.1% [3]. Patients who had positive surgical margins or margins of less than 2 mm had 5-year survival rates of 47% versus 72% in patients with wide margins [3]. Cases of STS in the infraspinatus muscle itself are rare. Four previous cases of sarcoma located in the infraspinatus muscle were found in a review of the literature. The first case, published in 1897, was in an 8-year-old child who underwent excision of the scapula [4]. A second case published in 1938 described a 17-year-old male patient who underwent surgical excision of the tumor, as well as at least part of the scapula [5]. A more recent publication describes a 28-year-old Japanese woman who underwent surgical excision of the infraspinatus muscle, part of the teres minor and teres major, and near-complete resection of the scapular periosteum [2]. The fourth case was noted in a study of function after a subtotal scapulectomy for bony or soft-tissue tumors among patients presenting to a university musculoskeletal oncology unit