Chordoma Presenting as a "Cold" Lesion on Bone Scintigraphy

Edward B. Cronin, M.D.

Henry D. Royal, M.D.

September 10, 1985

Case Presentation:

A 74 year-old male was admitted with several months of low back pain radiating into both legs and progressive difficulty in ambulation. He was taking no medications and had a forty pack per year smoking history.

Physical examination was remarkable only for mild (4/5) muscle weakness in both legs and loss of deep tendon reflexes at the ankles.

Findings:

He underwent metrizamide myelography (AP, Lat) and was found to have a complete block at T-12 (arrows on AP and Lat); the T-12 vertebral body appeared partially destroyed. A CT scan was performed a few hours later and demonstrated a retroperitoneal mass extending into the spinal canal at the level of the block and destruction of the T12 body. Neoplastic cells of uncertain origin were found at needle biopsy.

A bone scintigram demonstrated a focal "cold" lesion at T-12 (arrow), corresponding to the radiographically evident destructive lesion. There were no other abnormalities.

Radiation therapy was started, but because of progressive worsening of leg weakness and development of incontinence, a decompressive laminectomy was performed from T-11 to L-1. Cord compression, due to tumor within the spinal canal, was evident at surgery. Pathologically, the tumor was felt to represent a chordoma.

Discussion:

Bone scintrigraphy has traditionally been a "hot" spot imaging method. Improvements in equipment design have allowed detection of focal "cold" defects that may not have been appreciated in the past. Photopenic lesions are, however, difficult to recognize consistently; they may be obscured by overlying normal bone, or adjacent areas of increased uptake. Axial lesions, as in this case, tend to be easier to identify, because the higher count density in adjacent normal bone provides better contrast with the photopenic region.

Numerous reports of "cold" lesions on bone scintigraphy appear in the literature; most are caused by artifacts, loss of blood supply or loss of bone. Barium, jewelry, coins, pacemakers and orthopedic, breast or dental prostheses may cause artifacts which may not be easily recognized. Ischemic bone may be seen as a "cold" spot because perfusion is necessary for uptake of the radiopharmaceutical. Avascular necrosis, acute osteomyelitis, radiation therapy, frostbite, electrical burns, Gaucher's or sickle cell disease (with or without infarction), may cause sufficient ischemia to be reflected on a bone scan as a photopenic lesion. Bone loss is most commonly seen following surgical resection or arthroplasty; other entities include congenital anomalies such as absence of a pedicle, parietal thinning or midline sternal defect, benign conditions such as myelofibrosis, hemangiomas or brown tumors and malignancies, both primary and metastatic. Primary bone malignancies include multiple myeloma, osteolytic osteosarcoma and fibrosarcoma. A single case of a sacrococcygeal chordoma presented with a photopenic lesion has been reported. The most common metastatic lesions are from breast, lung and in children, neuroblastoma.

References:

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J. Anthony Parker, MD PhD, jap@nucmed.bih.harvard.edu