Ludloff Spot

An area of lucency in the distal femur between the medial and lateral femoral condyles is usually obscured by the patella on frontal views of the knee. On lateral views, a triangular triangular lucency, called the Ludloff spot, can be appreciated. CT images will show an area of lucency that can be mistaken for a lytic process.

References

De Wilde V, De Maeseneer M, Lenchik L, Van Roy P, Beeckman P, Osteaux M. Normal osseous variants presenting as cystic or lucent areas on radiography and CT imaging: a pictorial overview. Eur J Radiol. 2004 Jul;51(1):77-84.