Friday, August 29, 2008

Lost in Translation and a Hip Tumor

Some things are easily lost in translation. Witness the ineptly named Chinese Barbie-doll knock-off, "Benign Girl":

Something tells me that the manufacturer was trying to conjure up resonances of something besides a benign tumor when they named this product.

Clearly, language is important. For example, what is the difference between a benign and malignant tumor? The essential difference is their biologic behavior— benign tumors classically do not metastasize (spread to other sites), and typically grow more slowly than their malignant counterparts. Despite their less aggressive behavior, however, benign tumors can still be quite symptomatic.

Teenage boy who presents with left hip pain:
Coronal STIR image reveals a rounded, mixed-signal mass (red arrow) in the epiphysis of the left femoral head. There is extensive surrounding bone marrow edema, as well as a joint effusion.

(A) Axial T1-weighted and (B) T2-weighted images confirm the presence of the lesion, which is nearly isointense to the edematous cancellous bone:

Intravenous gadolinium was administered, and a subtraction image was obtained, confirming the presence of an enhancing tumor in the femoral epiphysis:

A CT scan was obtained for lesion characterization:

The lesion has internal matrix, with a pattern of rings and arc calcifications, characteristic of chondroid matrix. The lesion is well defined, and has a sclerotic rim. A pathologic fracture (blue arrow) is also identified.

The overall findings are highly suggestive of a chondroblastoma, which was confirmed at pathologic analysis.

Chondroblastomas typically arise in patients between the ages of 10 and 30. They almost always arise in the epiphysis. Although are regarded as a benign lesion, a small percentage can metastasize to the lungs.

On MRI, chondroblastomas are typically heterogeneous, but will often have some dark areas on T2-weighted images. They tend to generate a great deal of bone marrow edema, and will enhance after the administration of gadolinum. A subchondral epiphyseal tumor in the immature skeleton, associated with significant edema, is usually a chondroblastoma (Kan,J.H., & Kleinman,P.). The differential diagnosis includes a Brodie's abscess and Langerhans histiocytosis. Also to be considered, but much less likely, is an epiphyseal osteosarcoma or ganglion cyst filled with granulation tissue.

Vic David MD

1 comment:

drupal said...

Interesting case. A lesion in the epiphysis of the femur in a skeletally immature teenager should be considered very likely to be a chondroblastoma. Not really a serious diagnostic puzzle, so long as you know your bone tumors well. I noticed the "Benign Girl" barbie doll knock off pictured is a cell phone (or cell phone shaped toy) - not a doll. Just checkin' on ya.