Massive splenic metastases with localization of a skeletal imaging agent.

A 70 year old man with squamous cell carcinoma of the lung underwent Tc-99m sulfur colloid liver-spleen scintigraphy and abdominal CT studies; both studies showed multiple large lesions in the massively enlarged spleen, with a cystic appearance being noted on the CT examination. Two consecutive Tc-99m HMDP bone scintigrams demonstrated mild, diffuse radioactivity in the region of the spleen, indicating extraosseous localization of the bone imaging agent in the spleen and suggesting solid tumor masses rather than cysts. At autopsy, the huge spleen weighing 2,200 gm contained multiple, large, metastatic masses. Some of the masses were undergoing necrosis/liquification which would explain the cystic appearance on CT. While bone scintigraphy plays an important role in the detection of skeletal metastatic lesions, extraosseous localization of the imaging agent can provide additional diagnostic information.