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Metastatic superscan on 99mTc-MDP bone scintigraphy in a case of carcinoma colon: Common finding but rare etiology
Address for correspondence: Dr. Rakesh Kumar, E - 81, Ansari Nagar (East), All India Institute of Medical Sciences Campus, New Delhi - 110 029, India. E-mail: rkphulia@yahoo.com
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Abstract
Bone scintigraphy in which there is excessive skeletal radioisotope uptake in relation to soft tissues along with absent or faint activity in the genitourinary tract is known as a ‘superscan’. Prostate cancer is the most common malignancy associated with superscan along with others such as lung cancer, breast cancer and haematological malignancies. Here we present the case of a 41 year old woman with carcinoma colon with metastatic superscan on 99mTc-MDP bone scintigraphy, a very rare cause for metastatic superscan.
Keywords
Colon cancer
metastasis
99mTc-MDP bone scintigraphy
superscan
INTRODUCTION
A bone scan in which there is excessive skeletal radioisotope uptake in relation to soft tissues along with absent or faint activity in the genitourinary tract is known as a ‘superscan’.[1] Apart from prostate cancer, which is the most common condition associated with a superscan, other malignancies like breast cancer, lung cancer[1234] can cause superscan appearance on bone scintigraphy. Here we present a case of colon carcinoma with metastatic superscan on 99mTc-MDP bone scintigraphy, a very rare cause for metastatic superscan.
CASE REPORT
A 41-year-old woman underwent left hemicolectomy with excision of local lymph nodes two years back for carcinoma of the descending colon. No adjuvant chemotherapy was given and she was under routine follow up since then. Two years later she presented with backache. Her serum carcinoembryonic antigen (CEA) level was significantly elevated (490 ng/ml; normal: <2.5 ng/ml), as compared to her previous CEA levels (1.3 ng/ml) three months back. Plain radiography of the abdomen was normal. Contrast enhanced computed tomography (CT) of the abdomen, including the visualized bones was within normal limits [Figure 1]. Her serum alkaline phosphatase (805 IU/L; normal: 20-140 IU/L), serum calcium level (7.9 mmol/L; normal: 2.2-2.6 mmol/L) and serum phosphate level were all elevated (3.1 mmol/L; normal: 0.81-1.45 mmol/L). The patient was referred for 99mTc-MDP bone scintigraphy for metastatic work up. Her bone scintigraphy revealed intense radiotracer uptake involving almost the entire skeleton with high bone to soft tissue uptake [Figure 2]. The kidneys were very faintly visualized. These findings suggested ‘metastatic superscan’. Bone biopsy confirmed the diagnosis of metastatic carcinoma. The patient was started on chemotherapy, but she succumbed to her disease one month later.
DISCUSSION
Excessive skeletal radioisotope uptake in relation to soft tissues along with absent or faint activity in the genitourinary tract on bone scintigraphy is known as a ‘superscan’. Non-visualization of the kidneys in a bone scan should alert the physician for presence of a superscan in case the renal function is normal. Common causes include malignancies like prostate cancer, breast cancer, and lung cancer.[1234] Hematological conditions like leukemia, lymphoma, myelofibrosis, Waldenstrom's macroglobulinemia have been reported to be associated with a superscan.[56] It can also be seen in metabolic bone diseases like renal osteodystrophy, Paget's disease and hyperparathyroidism.[7] Occasionally superscan is seen in hyperthyroidism[8] and fibrous dysplasia.[9] Some of the rare causes for metastatic superscan include urinary tract transitional cell carcinoma and nasopharyngeal carcinoma.[10] However, to the best of our knowledge, superscan secondary to colon cancer has not been reported previously and is described here. Presence of a superscan usually indicates advanced stage of the disease, when there has already been extensive skeletal metastasis followed by an osteoblastic reaction. The patient prognosis is usually poor, as was in the present case.
Source of Support: Nil
Conflict of Interest: None declared
REFERENCES
- Accuracy of 99m Tc-diphosphonate bone scans and roentgenograms in the detection of prostate, breast and lung carcinoma metastases. Am J Roentgenol Radium Ther Nucl Med. 1975;125:972-7.
- [Google Scholar]
- 99Tc(m)(V)DMSA scintigraphy in skeletal metastases and superscans arising from various malignancies: Diagnosis, treatment monitoring and therapeutic implications. Br J Radiol. 2004;77:347-61.
- [Google Scholar]
- The headless bone scan: An uncommon manifestation of metastatic superscan in carcinoma of the prostate. Skeletal Radiol. 1988;17:111-3.
- [Google Scholar]
- Stratification of patients with metastatic prostate cancer based on extent of disease on initial bone scan. Cancer. 1988;61:195-202.
- [Google Scholar]
- Myelofibrosis presenting as hyper metabolic bone disease by radionuclide imaging in a patient with asplenia. Clin Nucl Med. 1978;3:406-8.
- [Google Scholar]
- “Normal” bone radionuclide image with diffuse skeletal lymphoma. A case report. Radiology. 1974;111:365-6.
- [Google Scholar]
- Technetium-99m-pyrophosphate bone scans in hyperparathyroidism. J Nucl Med. 1977;18:231-5.
- [Google Scholar]
- Hyperthyroidism: An underappreciated cause of diffuse bone disease. Clin Nucl Med. 1998;23:241-3.
- [Google Scholar]
- Increased skeletal: Renal uptake ratio: Etiology and characteristics. Radiology. 1980;136:455-9.
- [Google Scholar]