A punched-out lytic lesion without sclerotic rim — bevelled edges in the skull, vertebra plana in the spine — in a child; the skeletal survey or whole-body MRI decides single vs multisystem disease.
Orient first
- The skull is the commonest site; the "hole within a hole" is a bevelled edge.
- Vertebra plana (uniform collapse with preserved discs) is characteristic in children.
- Mimics: osteomyelitis, Ewing sarcoma — the lesion can be aggressive-looking.
Acquire the study
- Radiograph of the symptomatic site; skeletal survey or whole-body MRI for staging; CT for complex anatomy (skull base, orbit).
The manoeuvre
- Skull: round lytic lesion with bevelled edges and no sclerotic rim; size in mm.
- Spine lateral radiograph: vertebra plana with preserved disc spaces.
- Long bones: lytic diaphyseal lesion, endosteal scalloping, lamellated periosteal reaction.
What confirms it
- Biopsy (CD1a, langerin) of a compatible lesion.
What licenses you to exclude it
- Imaging cannot exclude LCH; a normal skeletal survey reduces the likelihood of multifocal bone disease.
The classic misread
- Calling LCH osteomyelitis or Ewing sarcoma — the answer is tissue.
- Missing pituitary involvement.