Age / Sex : 42 / F

Age / Sex : 42 years old / Female

Chief complaint : Left hip pain for 4 months

cortical metastasis

Discussion

Findings:

Initial bone scan – Mild radiotracer uptake on the left femur, lesser trochanteric area.

MR – An expansile soft tissue lesion which shows isointense on T1WI and hyperintense on inversion recovery and fat-suppressed T2WI with well contrast enhancement is seen at the lesser trochanter of the left femur. Surrounding marrow edema and soft tissue edema along the iliopsoas muscle are seen.

Follow up hip AP after 5 months later shows osteolysis of the lesser trochanter with interrupted periosteal reaction and osteolysis on the neck to subtrochanteric area of the left femur. And osteolysis on the superior portion of the right femur neck is also seen.

Follow up bone scan after 5 months later reveals peripherally increased radiotracer uptake on the intertrochanteric to subtrochanteric area of the left femur with focal hot uptake on the greater trochanter, and slightly increased uptake on the greater trochanteric area of the right femur.

Differential Diagnosis: Metastasis

                      Lymphoma

                       Plasmacytoma or multiple myeloma

Diagnosis:  Cortical Metastasis from breast cancer

     Past history with diagnosis of breast cancer (invasive ductal carcinoma) 1 year ago treated with partial mastectomy with axillary lymph node dissection, chemotherapy and radiotherapy

Discussion:

 Skeletal metastasis is the result of hematogenous disseminationof tumor cells by the systemic arterial circulation. Characteristically most metastases begin from the medullary cavity.

 The cortex has a distinct intracortical vascular network of intercommunicating capillaries that are supplied by anastomotic branches from periosteal, medullary, and nutrient artery vessels. As a result arterial disseminated metastases can potentially arise in an intracortical or subperiosteal location.

 Predominantly cortical or subperiosteal metastases have been reported from breast, kidney, lung, thyroid, liver pancreas, GI tract, bone, larynx, uterus, epidermoid primary tumors, and melanoma.

 A large majority of the lesions occur in the tibia and femur followed by humerus. The lesions show diaphyseal or metadiaphyseal location, especially in the posterior or medial quadrants of. Bones.

 Radiographically cortical metastasis shows geographic or moth eaten osteolytic destruction with cooki-bite pattern.

Cortical metastasis are categorized into 4 types; metastasis confined to the cortex (type 1), esxtension into the soft tissue (type 2), extension into the marrow cavity (type 3), and predominantly subperiosteal location (type 4).

References:

1. Hendrix RW, Rogers LF, Davis TM. Cortical bone metastases. Radiology 1991;181:409-413

2. Coerkamp EG, Kroon HM. Cortical bone metastases. Radiology 1988;169:525-528

3. Shin YR, Kim JY. Intracortical bone metastasis mimicking intracortical osteoid osteoma: a case report. J Korean Radiol Soc 2007;57:181-185