Patient Data
A focal lytic lesion measuring 5cm superoinferiorly affects the proximal femur medially, just inferior to the lesser trochanter. The cortical bone appears expanded in this region but even with the expansion it is markedly eroded with risk of fracture.
A 20 x 18 x 40 mm left medial proximal femoral cortically based well-defined lytic lesion with a small medial cortical breach is noted. It has a sharply defined zone of transition. No calcified or ossified internal matrix. No appreciable soft tissue mass identifiable on CT.
A whole body bone scan was performed. Prominent uptake is seen in the maxillary regions bilaterally (left > right). Moderate uptake is seen in the left mastoid process. Intense linear uptake is seen in the medial aspect of the left upper femur. No other significant abnormalities are seen.
Case Discussion
This patient has known (pathologically confirmed) Langerhans cell histiocytosis involving the skull and left femur. He went on to have prophylactic intra-medullary nail placement to prevent a fracture. The location of this lesion, within the cortex, is somewhat atypical with most such lesions located within the medullary cavity - appearance is however variable.