12 years old male.
Skeletal manifestations of Langerhans cell histiocytosis
The skeleton is the most commonly involved organs system in Langerhans cell histiocytosis (LCH) and is by far the most common location for single lesion, often referred to as eosinophilic granuloma (EG) (the terms are used interchangeably in this article). For a general discusion of this disease please refer to the article on Langerhans cell histiocytosis (LCH).
The skeletal system is the commonest site of involvement of Langerhans cell histiocytosis, and in for 60-80% of cases is the only organ system involved. It primarily occurs in older children and young adults, with a male preponderance with a male to female ratio of 2:1.
The lesions may be asymptomatic and discovered as an incidental radiographic finding.
When symptomatic, patients complain of pain, swelling and tenderness around the lesion. Systemic symptoms may also be present, including general malaise and, on occasion, fever with leukocytosis.
There is proliferation of Langerhans cells with an abundance of eosinophils, lymphocytes and neutrophils. These cells produce prostaglandins which result in medullary bone resorption: it is this that causes the symptoms.
Location / distribution
Patients may have one or many lesions. The most common locations are 5-6:
• skull: 49%
• pelvis: 23%
• femur: 17%
• ribs: 8% (most common in adults)
• humerus: 7%
• mandible: 7%
• solitary or multiple punched out lytic lesions with or without sclerotic rim
• double contour or beveled edge appearance may be seen. Greater involvement of the inner than the outer table.
• button sequestrum representing residual bone
• geographic skull
• irregular radiolucent areas mostly involving superficial alveolar bone
• floating tooth: loss of lamina dura.
• vertebra plana, more often in thoracic spine
• mainly involves diaphysis and respect growth plates
• endosteal scalloping, periosteal reaction, cortical thinning and intracortical tunneling
Similar to plain film findings with better demonstration of cortical erosion and soft tissue involvement. Excellent for biopsy and surgical planning.
Signal characteristics include
• T1 - typically low signal
• T2 - isointense to hyperintense
• T1 C+ (Gd) - often shows contrast enhancement
Variable appearance on bone scintigraphy with lesions showing an increased or decreased tracer uptake depending on the histological picture. Nonetheless bone scans are helpful in other asymptomatic lesions.
Treatment and prognosis
The prognosis is excellent when disease is confined to the skeleton, especially if it is a solitary lesion, with the majority of such lesions spontaneously resolving by fibrosis within 1-2 years. However, where symptoms persist, other treatment options may be considered.
• excision and curettage 3
• steroid therapy
• radiofrequency ablation 4
The term eosinpophilic granuloma was coined by Lichenstein and Jaffe in 1940 2
General imaging differential considerations include
• round blue cell tumours
• primary bone tumours
• lymphoma / leukemia
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