Metastases of Germ Cell Tumor Mimicking Paget's Disease

Abstract

A bone scan done for a 58-year-old man with intense pain in the lower back and pelvis, showed intense MDP uptake in most of the pelvis, in the proximal aspect of the left femur, D-8 vertebra, and a focal area of uptake in the skull. The features were suggestive of Paget's disease. An x-ray of pelvis revealed multiple sclerotic lesions in the pelvis (left ischium, acetabulum, and supra-acetabular regions of left ilium, right acetabulum, the left femoral neck, and left hip joint), suggesting metastases. On clinical examination, he had a left hydrocele. Peroperatively, a mass was found in the left testis for which a left orchidectomy was done. The histopathology was high-grade malignant germ cell tumor. Fine needle aspiration cytology from the pelvis confirmed the presence of metastases from germ cell tumor.

Mickey Mouse Sign on Bone Scan

“…1 However, a few cases in the literature have demonstrated that metastatic lesions from germ cell tumor and hepatocellular carcinoma have mimicked radiotracer uptake patterns classically seen in Paget disease. 7,8 Considering this, it is important to keep metastatic disease in the differential diagnosis when such diffuse vertebra uptake involving the body, posterior elements, transverse, and spinous processes is seen on whole-body radionuclide bone scan, as such appearance can also be caused by other entities, especially in the presence of multifocal osseous disease as was seen in our case in a patient with prostate cancer.…”

“…The presence of “Mickey Mouse sign” on radionuclide bone scan is reported to be more suggestive of Paget disease than metastasis, even in patients with cancer with a positive predictive value of 88% when patients who had definite evidence of multiple metastases were excluded and 70% when they were included 1 . However, a few cases in the literature have demonstrated that metastatic lesions from germ cell tumor and hepatocellular carcinoma have mimicked radiotracer uptake patterns classically seen in Paget disease 7,8 . Considering this, it is important to keep metastatic disease in the differential diagnosis when such diffuse vertebra uptake involving the body, posterior elements, transverse, and spinous processes is seen on whole-body radionuclide bone scan, as such appearance can also be caused by other entities, especially in the presence of multifocal osseous disease as was seen in our case in a patient with prostate cancer.…”