Striking a chord

A 20-year-old woman presented with anemia (Hgb 6.2 g/dL), circulating immature cells (80/cmm), and compression fractures of the thoracic and lumbar spine. Bone marrow biopsy was performed to evaluate for acute leukemia. Aspirate smears were hypercellular, showing large vesicular cells with round nuclei and abundant foamy cytoplasm, singly and in clusters (panel A; original magnification ×100). Biopsy revealed near-complete replacement of the marrow space by vacuolated cells arranged in nests, cords, and sheets (panels B-C; original magnification ×4 [B], ×50 [C]). These cells were negative for a battery of stains, including CD45, CD68, CD163, and CD1a. They were positive for keratin AE1-AE3 (panel D; original magnification ×50), epithelial membrane antigen (panel E; original magnification ×50), and periodic acid–Schiff (panel F; original magnification ×50). Brachyury, performed at an outside institution, was also positive. Follow-up computed tomography of this patient showed innumerable lytic lesions in the axial skeleton as well as hepatic hypodensities. The patient died 3 months later.

The morphologic and immunohistochemical features were diagnostic of chordoma, a rare, slow-growing malignant tumor characterized by cords of glycogen-rich physaliferous cells that arises from notochordal remnants. Chordomas typically have a nonspecific presentation and more advanced disease at diagnosis. Metastasis is infrequent, with lung being most common. Despite slow progression, prognosis is poor because patients are generally chemoresistant. Treatment is surgical with or without radiation.