Answer for BIR CoW 20 Jul 2025
Blowout metastasis
Findings
Expansile relatively well-defined lytic bone with soft tissue components noted in left iliac wing and posterior aspect of right 7th and 8 th ribs on right side. Impression: Known case of follicular carcinoma of thyroid , post total thyroidectomy on 03/05/25 Present study shows, Blow out osteolytic bone metastasis involving 7, 8 th right rib and left iliac bone.
Discussion
“blow-out metastasis” refers to a lytic bone metastasis that causes expansile destruction of bone, typically without much reactive sclerosis or periosteal reaction. These lesions often appear aggressive and can mimic primary bone tumors or infections on imaging. The term “blow-out” reflects the ballooning or expansile nature of the lesion that “blows out” the cortical bone. Key radiological features: Lytic lesion with expansile margins Cortical thinning or destruction Often no sclerotic rim Minimal or no periosteal reaction May contain soft tissue mass MRI: Shows high T2 signal with possible soft tissue extension CT: Better delineation of cortical destruction Bone scan: May show increased uptake due to hypervascularity Common Primaries Associated with Blow-out Metastasis: These typically arise from hypervascular tumors, such as: - Renal cell carcinoma (RCC) - Thyroid carcinoma - Adrenal carcinoma - Hepatocellular carcinoma - Occasionally lung or breast carcinoma Differential diagnosis: - Primary bone tumors (e.g., giant cell tumor, aneurysmal bone cyst) - Multiple myeloma - Langerhans cell histiocytosis - Infection (e.g., osteomyelitis)
References:
1. Adam Greenspan, Gernot Jundt, Wolfgang Remagen. Differential Diagnosis in Orthopaedic Oncology. (2007)
2. Nakanishi K, Kobayashi M, Nakaguchi K et al. Whole-Body MRI for Detecting Metastatic Bone Tumor: Diagnostic Value of Diffusion-Weighted Images. Magn Reson Med Sci. 2007;6(3):147-55. doi:10.2463/mrms.6.147 - Pubmed
3. Donald Resnick, Mark J. Kransdorf. Bone and Joint Imaging. (2005)
4. Charles A. Rockwood (Jr.), David P. Green, Robert W. Bucholz. Rockwood and Green's Fractures in Adults. (2010)
Findings
Expansile relatively well-defined lytic bone with soft tissue components noted in left iliac wing and posterior aspect of right 7th and 8 th ribs on right side. Impression: Known case of follicular carcinoma of thyroid , post total thyroidectomy on 03/05/25 Present study shows, Blow out osteolytic bone metastasis involving 7, 8 th right rib and left iliac bone.
Discussion
“blow-out metastasis” refers to a lytic bone metastasis that causes expansile destruction of bone, typically without much reactive sclerosis or periosteal reaction. These lesions often appear aggressive and can mimic primary bone tumors or infections on imaging. The term “blow-out” reflects the ballooning or expansile nature of the lesion that “blows out” the cortical bone. Key radiological features: Lytic lesion with expansile margins Cortical thinning or destruction Often no sclerotic rim Minimal or no periosteal reaction May contain soft tissue mass MRI: Shows high T2 signal with possible soft tissue extension CT: Better delineation of cortical destruction Bone scan: May show increased uptake due to hypervascularity Common Primaries Associated with Blow-out Metastasis: These typically arise from hypervascular tumors, such as: - Renal cell carcinoma (RCC) - Thyroid carcinoma - Adrenal carcinoma - Hepatocellular carcinoma - Occasionally lung or breast carcinoma Differential diagnosis: - Primary bone tumors (e.g., giant cell tumor, aneurysmal bone cyst) - Multiple myeloma - Langerhans cell histiocytosis - Infection (e.g., osteomyelitis)
References:
1. Adam Greenspan, Gernot Jundt, Wolfgang Remagen. Differential Diagnosis in Orthopaedic Oncology. (2007)
2. Nakanishi K, Kobayashi M, Nakaguchi K et al. Whole-Body MRI for Detecting Metastatic Bone Tumor: Diagnostic Value of Diffusion-Weighted Images. Magn Reson Med Sci. 2007;6(3):147-55. doi:10.2463/mrms.6.147 - Pubmed
3. Donald Resnick, Mark J. Kransdorf. Bone and Joint Imaging. (2005)
4. Charles A. Rockwood (Jr.), David P. Green, Robert W. Bucholz. Rockwood and Green's Fractures in Adults. (2010)
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!