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A super
scan in scintigraphy is defined as intense symmetric radiotracer activity in
the bones, increased bone: soft tissue uptake ratio and diminished renal
parenchymal uptake. Carcinoma prostate, breast and lung are common malignancies
known to cause ‘metastatic’ super scan, indicating disseminated skeletal
metastases. Here we present a case of metastatic super scan on 99mTc‑MDP
bone scintigraphy in a poorly differentiated gastric adenocarcinoma with signet
ring cell component arising from distal body and incisura of the stomach of a
37 years old lady who presented with loss of appetite and occasional vomiting.
Keywords: Super scan, Bone scan, Carcinoma, Stomach,
Disseminated skeletal metastasis
INTRODUCTION
A super scan in scintigraphy is defined as
intense symmetric radiotracer activity in the bones, increased bone: soft
tissue uptake ratio and diminished renal parenchymal activity [1]. When the
metastatic disease diffusely involves bones, it causes excessive skeletal radioisotope
uptake in 99m-Tc bone scan. There is little or no activity in the soft tissues
or urinary tract. Prostate cancer is the most common cause of ‘metastatic’
super scan. Other malignancies known to be associated with super scan are
breast and lung cancer [2]. Here we present a case of metastatic super scan on
99mTc‑MDP bone scintigraphy in a poorly differentiated gastric adenocarcinoma
with signet ring cell component arising from distal body and incisura of the
stomach of a 37 years old lady who presented with loss of appetite and occasional
vomiting.
CASE REPORT
A 37 years old house wife from Bangladesh
presented with unexplained loss of appetite and occasional vomiting for last 3
months. Endoscopy revealed an ulcerated lesion in the distal body and incisura
of the stomach. An asymmetrical circumferential wall thickening involving
antro-pyloric region of stomach was detected in USG upper abdomen. Biopsy from
distal stomach tumor diagnosed a poorly differentiated adenocarcinoma with
signet ring cell component. Immunohistochemistry done for cytokeratin (AE1/AE3)
highlighted the invasive tumor cells (Figure
1). Her renal parameters were within normal limit (urea 15 mg/dl, creatinine
0.47 mg/dl).
The patient was referred for 99mTc‑MDP
bone scintigraphy as a part of metastatic work up. Her bone scan revealed
intense radiotracer uptake involving almost the entire axial and proximal
appendicular skeleton with high bone to soft tissue radiotracer uptake ratio.
The kidneys and urinary bladder were very faintly visualized. These findings
were consisted with ‘metastatic super scan’ (Figure 2). CT scan of thorax and whole abdomen done at
the same time showed diffuse involvement of all visualized bones with mixed
lytic sclerotic lesions consistent with bone metastases (Figure 3A). CT scan also showed bilateral enlarged ovaries with
solid, cystic mass lesions consistent with Krukenbergs tumor. No lung or breast
lesion was detected.
The patient was advised palliative
chemotherapy. Review after four cycles of chemotherapy showed no significant
change of the primary lesion as well as metastatic diseases in follow up CT
scan (Figure 3B).
DISCUSSION
Skeletal uptake of 99m-Tc MDP depends upon
blood flow to the area and bone remodeling activity-in particular new bone
formation. Intense activity in bone scintigraphy in diffuse metastatic disease
can be explained by diffuse bone marrow involvement [1]. Less frequently, multiple
metabolic diseases cause diffuse skeletal uptake of 99m-Tc MDP simulating
‘super scan’. Hyperparathyroidism, renal osteodystrophy, hyperthyroidism and
hypervitaminosis D are associated with scintigraphic super scan. Metabolic
super scan is more uniform in appearance than metastatic super scan, frequently
involving distal appendicular skeleton and causes intense calvarial uptake that
is disproportionate to that in the remainder of the skeleton [3]. The exact
mechanism of ‘metabolic’ super scan is unknown. Gastric cancer frequently metastasizes to liver and peritoneum.
Overall incidence of bone metastasis from gastric cancer is found to be around
10 to 12 percent [4,5]. Bone metastasis is more frequently seen in cancer at
cardia than distal end of stomach. Signet ring cell adenocarcinoma has a
predilection to be associated with bone metastasis [4]. However, skeletal
metastasis from gastric adenocarcinoma is most commonly osteoclastic in nature.
A combination of osteolytic and osteosclerotic lesions are seen less
frequently. Osteoblastic metastasis is an unusual feature of gastric cancer and
infrequently reported in literature [6]. The osteoblastic metastasis in gastric
cancer usually is seen in advance stage of disease and associated with poor
prognosis. In gastric cancer patients, significantly better survival period was
observed in patients with singular bone metastasis rather than multiple
skeletal deposits [7].
CONCLUSION
Gastric adenocarcinoma which more frequently
causes osteoclastic or mixed osteoclastic-osteosclerotic skeletal metastases
may rarely produce disseminated osteoblastic metastasis. Diffuse osteoblastic
metastases from gastric adenocarcinoma, especially signet ring cell adenocarcinoma
from distal stomach can rarely cause ‘metastatic’ super scan.
1. Pour MC, Simon-Corat Y, Horne T (2004) Diffuse
increased uptake on bone scan: Super scan. Semin Nucl Med 34: 154-156.
2. Manohar PR, Rather TA, Khan SH, Malik D (2017)
Skeletal metastases presenting as super scan on technetium 99m methylene
diphosphonate whole body bone scintigraphy in different type of cancers: A
5-year retro-prospective study. World J Nucl Med 16: 39-44.
3. Chatterjee P, Mukherjee A, Mitra D, Nautiyal A, Roy
A (2017) Super scan on methylene diphosphonate skeletal scintigraphy in
prostatic adenocarcinoma: A common finding but rare etiology. Indian J Nucl Med
32: 369-371.
4. Riihimäki M, Hemminki A, Sundquist K, Sundquist J,
Hemminki K (2016) Metastatic spread in patients with gastric cancer. Oncotarget
7: 52307-52316.
5. Silvestris N, Pantano F, Ibrahim T, Gamucci T, Vita
FD, Palma TD, et al. (2013) Natural history of malignant bone disease in
gastric cancer: Final results of a multicenter bone metastasis survey. PLoS One
8: e74402.
6. Ermiş F, Erkan ME, Besir FH, Oktay M, Kutlucan A,
et al. (2014) Osteoblastic metastasis from signet ring cell gastric cancer in a
young male. Turk J Gastroenterol 25: 284-286.
7. Ahn JB, Ha TK, Kwon SJ (2011) Bone metastasis in
gastric cancer patients. J Gastric Cancer 11: 38-45.
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