Orthopaedic Oncology cases Mirel scoring system? RANKL pathway

A 49-year-old female with stage IV breast cancer presents to your office with worsening left hip pain. A recent bone scan ordered by her oncologist identifies multiple lesions in the spine, right humeral shaft, left clavicle, right ilium, and left proximal femur. She recently underwent radiation to the spine, left proximal femur, and right humeral shaft.

Which of the following is not included in Mirel scoring system?

1. Size of the lesion

2. Pain associated with the lesion

3. Lytic or blastic characteristics of the lesion

4. History of radiation to the lesion

 

Discussion

The correct answer is (D). Mirel scoring system is used to predict the risk of pathologic fracture in patients with metastatic bone lesions. The four criteria used to judge the risk are: radiographic appearance (blastic/mixed/lytic), size of the lesion

(as a proportion of the shaft diameter), site, and characteristics of pain.

 

What is the mechanism behind bone destruction in a metastatic lesion, such as the one in these x-rays?

1. Tumor cells destroy the bone through direct extension into bone

2. Tumor cells stimulate osteoclasts to resorb bone

3. Tumor cells engulf cells comprising the bony trabeculae

4. an inflammatory response to tumor metastasis in the bone causes secretion of osteoclast-stimulating cytokines

Discussion

The correct answer is (B). Tumor cells secrete cytokines that stimulate the RANKL pathway; osteoclasts have RANK receptors for RANKL. Osteoblasts upregulate their secretion of RANKL within metastatic lesions, causing an upregulation in osteoclast precursors and eventually increased bone destruction.

What intervention would you recommend for her hip?

1. Prophylactic fixation with long cephalomedullary nail

2. Prophylactic fixation with short cephalomedullary nail

3. Prophylactic fixation with dynamic hip screw device with two-hole plate

4. Protected weight-bearing restriction and observation

 

Discussion

The correct answer is (A). The patient has an impending fracture, therefore she is indicated to have the lesion stabilized with a long cephalomedullary device. In prophylactic fixation, in cases of metastases, it is recommended to use an implant which protects the entire bone, such as a long intramedullary nail, in anticipation of potential development of another lesion elsewhere in the bone.

 

Objectives: Did you learn...?

 

 

Mirel scoring system? RANKL pathway?