Metastatic Carcinoma




CLINICAL SUMMARY


Metastatic carcinoma accounts for the large majority of bone malignancies and, along with multiple myeloma, is the first consideration for any destructive bone lesion in a patient older than 40 years. The primary treatment for symptomatic bone metastases is radiation therapy. Prophylactic internal fixation should especially be considered for destructive peritrochanteric femur lesions.




DIAGNOSTIC FEATURES





















History


  • Older than 40 years



  • The malignancies that are most likely to metastasize to bone are breast, lung, prostate, kidney, and thyroid



  • Pain more common with lytic metastases than with blastic lesions

Location


  • Typically intramedullary



  • Lung and kidney metastases can originate in cortex



  • Distribution: preference for hematopoietic sites, i.e., ribs, spine, pelvis, proximal femur



  • Metastatic carcinoma uncommon distal to the elbow and knee

Margins


  • Lytic metastases can demonstrate geographic to motheaten/permeative bone destruction

Matrix


  • Variable



  • Prominent reactive bone formation can be seen in breast, thyroid, and prostate metastases






IMAGING








































  • Bronchogenic carcinoma appears as a mass ( arrow ) adjacent to the left hilum on chest x-ray ( left ).



  • In a patient with known cancer, the presence of two or more lesions, as demonstrated here with a bone scan ( right ), corresponds to a greater than 90% probability of metastatic disease.










  • Breast cancer metastasis appears as a mixed lytic and blastic lesion in the left pelvis and femur ( left ). This pattern can also be seen in thyroid cancer. Note also pathologic acetabulum fracture.



  • In this example, metastatic breast carcinoma appears as an area of aggressive lytic bone destruction in the proximal femur ( right ).










  • Prostate cancer produces blastic metastases ( arrows ) in 75% of instances ( left ). Note the radiation seeds in the prostate.



  • Metastases originating in the cortex appear as “cookie bites” ( arrow ) and are most commonly seen with lung and kidney carcinomas ( right ).










  • Distal (acral) metastases are unusual but most commonly seen with lung cancer ( left ).



  • Metastatic lesions in children are most commonly neuroblastomas, as seen in this forearm lesion ( right ).










  • Destructive lesions about the peritrochanteric region, as seen on this radiograph ( left ), should raise concern about an impending pathologic fracture. Often, pain precedes the fracture.



  • MRI (STIR sequence) shows marrow and soft tissue edema, increasing concern about an impending fracture ( right ).


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