Findings: Increased radiopharmaceutical activity in ankles and knees consistent with degenerative changes. Increased radiopharmaceutical activity in the RUQ consistent with metastatic disease to the liver.

Diagnosis: Metastatic Disease of the Liver.

Discussion: Abnormal radiopharmaceutical activity on a bone scan can be visualized in multiple settings. Obviously, activity would be thought to be seen in osseous metastasis, but activity will also be seen in non-osseous metastatic disease. Colon, pancreas, and ovarian soft tissue metastasis are notable for having increased activity at metastatic sites. Some primary non-osseous neoplasms that demonstrate increased activity include thyroid, lymphoma, lung, neuroblastoma, breast and hemangioma. Even without the presence of ectopic calcification, increased radiopharmaceutical activity can be visualized. This is thought to be due to the disruption of the cell membrane and loss of calcium-Phosphate pump, and therefore deposition of cellular calcium into the cell. Considering this information, it is clear to see how other mechanisms can cause abnormal radiopharmaceutical activity, such as fat necrosis, hepatic necrosis, infarction or vascular insult, and radiation treatment ports. Other entities that can cause soft tissue accumulation include: Fluid collections-effusions, ascites, etc., uremia, sickle cell disease, rhabdomyolysis, amyloidosis, scleroderma, sarcoid, hyper/hypoparathyroidism, hyperthyroidism, and drugs-Adriamycin toxicity, and iron dextran and injections.

References:
Gottschalk A, Hoffen P, Potchen EJ. Diagnostic Nuclear Medicine, 2nd Edition.
Williams and Wilkins, Baltimore; 1988:1071.

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