Langerhans cell histiocytosis

There is severe uniform joint space narrowing of the left femoroacetabular joint with moderate osteophytosis.  The left proximal femur, para-acetabular innominate, anterior ilium, and left sacroiliac joint show multiple, well-defined, irregularly shaped lytic lesions with mild surrounding blastic changes. None of these sites show a distinct area of cortical disruption or periosteal reaction. There is mild to moderate distension of the left capsular and psoas fat pads. 

The multiple focal lytic lesions with mild surrounding sclerosis are re-identified. There are intramedullary and extramedullary components of the polyostotic lytic lesions with areas of cortical breach, but no periosteal reaction. No fractures are identified. 

The patient was placed in the supine position on CT scanner table, and an initial scan was performed to localize the lesion.  The skin was then prepped and draped in a sterile fashion.  The skin and subcutaneous tissues were anesthetized with 1% lidocaine.  A small dermatotomy was made, and a coaxial needle was inserted into the left proximal femur under CT guidance.  Once in appropriate position, a 14-gauge biopsy needle was used to obtain tissue samples. Pre and post images demonstrated appropriate position of the biopsy needle within the mass.  Once adequate tissue samples were obtained, the coaxial needle was removed.