2. Etiology
• Langerhans cell histiocytosis is due to uncontrolled monoclonal
proliferation of Langerhans cells (distinctive cells of monocyte-
macrophage lineage)
• Triggers : EBV, HHV-8, Smoking
• This proliferation is accompanied by inflammation and granuloma
formation and medullary bone resorption.
• older children and young adults, with a male to female ratio of 2:1
3. The skeleton is the most commonly involved organ
(osteolytic lesion)
• Skull: ~50%
• Pelvis: 23%
• Femur: 17%
• Ribs: 8% (most common in adults)
• Humerus: 7%
• Mandible: 7%
• Spine
4. Skull
BUTTON SEQUESTRUM SIGN
• Manifestation in the mildest form of LCH.
• Bone is replaced by erosive accumulation of histiocytes
– appears lucent
• Central opacity – island of dead bone
5.
6. HOLE WITHIN A HOLE SIGN
Solitary or multiple osteolytic lesion with ill-defined margins and a non-sclerotic
border
The bevelled edge of the defects is due to asymmetrical destruction of both inner
and outer tables of the skull, giving the appearance of two overlapping lytic lesions
of unequal size on x-ray.
7. GEOGRAPHIC SKULL
It is characterised by multiple destructive lytic bone lesions, the edges of
which may be bevelled, scalloped or confluent.
Large map-like
regions of
radiolucency -
geographic skull.
8. MANDIBLE
FLOATING TEETH SIGN
• Tooth appears like “hanging in wind” or “swinging in air”
• destruction of the supporting alveolar bone around the root
of the teeth involving the mandible.
9. FLOATING TEETH
Lamina dura - compact bone that lies adjacent to the periodontal ligament, in the tooth
socket. It surrounds the tooth socket and provides the attachment surface with which
the Sharpey's fibers of the periodontal ligament perforate.
10. Floating Tooth: loss of lamina dura
Irregular radiolucent areas mostly involving superficial alveolar bone
11. SPINE
VERTEBRA PLANA
• Pancake vertebra
• Coin on edge appearance
• Silver dollar sign
Commonest cause of solitary vertebra plana in
children.
12. loss of vertebral height as thin as 2 mm involving both the anterior and posterior
vertebral surfaces of body.
13. • Aseptic necrosis of the
vertebral body involving both
the anterior and posterior
vertebral surfaces of body
• Posterior elements are usually
spared.
• Predilection for thoracic spine
> lumbar spine > cervical.
Editor's Notes
button sequestrum representing residual bone
A button sequestrum is a small sequestrum of devascularised bone surrounded by lucency. Although classically described in osteomyelitis and eosinophilic granuloma it is also occasionally seen in fibrosarcoma and lymphoma.
Differential diagnoses
osteoid osteoma
tuberculous osteomyelitis
radiation necrosis
skeletal metastasis
fibrous dysplasia
epidermoid and dermoid cyst
haemangioma
The hole within a hole sign or bevelled edge sign describes one classic appearance of lytic skull lesions in patients with eosinophilic granuloma. The bevelled edge of the defects indicates asymmetrical destruction of both inner and outer tables of the skull, giving the appearance of two overlapping lytic lesions of unequal size on x-ray 1,2.
The other common appearance for a lytic lesion of eosinophilic granuloma is a "punched out" lesion with well-defined margins and a non-sclerotic border 1
Skull
solitary or multiple punched out lytic lesions without sclerotic rim
double contour or beveled edge appearance may be seen due to asymmetrical involvement of the inner and outer tables (hole within a hole) sign 7
button sequestrum representing residual bone
geographic skull
A geographic skull is a radiographic appearance which is seen in eosinophilic granuloma (EG) and characterised by destructive lytic bone lesions, the edges of which may be bevelled, scalloped or confluent.
irregular radiolucent areas mostly involving superficial alveolar bone
floating tooth: loss of lamina dura
Vertebra plana (pleural: vertebrae planae), also known as the pancake or silver dollar or coin-on-edge vertebra, is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced compression fracture.
