Chondrosarcoma of scapula - Erler Zimmer
Clinical History
A 60-year-old female presented with a 12-month history of recurring pain and increasing swelling in her right shoulder. During examination, a palpable mass was identified over the superior aspect of her right scapula, accompanied by limited abduction and external rotation at the shoulder joint. No palpable lymphadenopathy was observed. X-ray imaging of her shoulder revealed a mass involving the superior scapula above the spine. Subsequently, the mass was biopsied, and the entire scapula was excised.
Pathology
The specimen consists of the patient's excised right scapula, revealing an irregular lobulated tumor measuring 11 cm in maximum diameter. The tumor arises from the spine of the scapula, extending to involve the acromion and coracoid process. It exhibits a mottled pale-yellow-brown color with patchy surface hemorrhage, adherent muscle, and fibrous tissue. The mass has infiltrated and replaced the normal bone. Histologically, the tumor comprises pleomorphic rounded and spindle-shaped cells with numerous mitotic figures and cartilage formation, confirming the diagnosis of chondrosarcoma of the scapula.
Further Information
Chondrosarcomas are malignant bone tumors that produce cartilage, ranking as the third most common primary bone malignancy after myeloma and osteosarcoma. The most prevalent subtype is conventional chondrosarcoma, constituting 90% of cases. Less common subtypes include clear cell, dedifferentiated, and mesenchymal chondrosarcomas.
Some chondrosarcomas arise from pre-existing benign lesions, such as enchondroma or osteochondroma. Common mutations in chondrosarcomas include point mutations in the IDH1 and IDH2 genes, as well as silencing of the CDKN2A tumor suppressor gene. Chondrosarcomas associated with multiple osteochondroma syndrome have mutations in the EXT genes. Men are twice as likely to develop chondrosarcoma than women, and the axial skeleton is more frequently affected than the appendicular skeleton. Approximately 5% affect the scapula. These are generally slow-growing tumors, typically presenting with painful and gradually enlarging masses. At the time of diagnosis, most are low-grade tumors that rarely metastasize. The lungs are the most common site for distant spread. Grade 1 tumors have an almost 90% 5-year survival rate, whereas with grade 3 chondrosarcomas, the 5-year survival rate drops to 43%.
CT scans are optimal for radiological diagnosis, with MRI also commonly used. Biopsies may assist in diagnosis. Treatment depends on the grade and location of the tumor, with complete surgical resection as the standard. Generally, chondrosarcomas do not respond well to chemotherapy or radiotherapy due to their very slow growth.
