CASE 18242 Published on 12.08.2023

Langerhans Cell Histiocytosis of the skull in a toddler

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

Antoine Vandendriessche1,2, Filip Vanhoenacker2,3,4

1. Faculty of Medicine, Vrije Universiteit Brussel, Belgium

2. Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium

3. Department of Radiology, UZ Antwerpen, University of Antwerp, Belgium

4. Department of Radiology, UZ Gent, Faculty of Medicine, Ghent, Belgium

Patient

3 years, female

Categories
Area of Interest Abdomen, Anatomy, Artificial Intelligence, CNS, Interventional non-vascular, Interventional vascular, Musculoskeletal bone, Musculoskeletal joint, Musculoskeletal soft tissue, Musculoskeletal spine, Neuroradiology brain, Paediatric ; No Imaging Technique
Clinical History

A 3-year-old female patient was referred to the department of radiology complaining of a painful cranial swelling on the right side. The swelling was first noticed following a fall on the head 1 month ago and did not regress over time. No neurological or other systemic symptoms were noted.

Imaging Findings

Computer tomography (CT) showed multifocal osteolytic lesions scattered throughout the skull with non-sclerotic borders and asymmetrical involvement of the inner- and outer table (bevelled edges) (Figure 1). A hypodense subgaleal soft tissue swelling is noted at one of the larger lesions.

Ultrasound (US) revealed multiple defects at the calvaria with intralesional solid soft tissue lesions of heterogeneous echogenicity. Color doppler showed subtle intralesional flow (Figure 2).

Magnetic resonance imaging (MRI) confirmed multiple calvarial lesions, all iso-intense to adjacent brain tissue on T1-weighted images (WI). One of the larger lesions was located peri-orbitally, and slight proptosis was noted. On T2-WI, the lesions were heterogeneously hyperintense, and after administration of gadolinium contrast, there was vivid heterogeneous enhancement. A subtle dural tail was seen adjacent to some lesions. Limited diffusion restriction was noted (Figure 3). In addition, there were multiple lytic lesions at the skull base.

Discussion

Langerhans Cell Histiocytosis (LCH) is a rare disorder, more common in children, characterized by idiopathic clonal proliferation of histiocytes, also called Langerhans cells, a type of immunological cell [1].

Proliferation can occur in various organ systems such as skin, lungs, central nervous system, liver, lymph nodes, and bone marrow. Depending on whether one or more systems are affected with single or multiple foci, we refer to single- or multisystem and uni- and multifocal involvement. Skeleton involvement is frequent and can involve either single or multiple bones with preferred locations in the pelvis, long bones, spine and skull. A solitary skull lesion in children is the most common presentation of LCH [2].

Clinical findings depend on the lesion’s extension and location of the disease. Skull LCH usually manifests as a painful swelling at the scalp [3].

When dealing with a lump at the scalp, ultrasound (US) is usually the initial examination in children in order to avoid radiation exposure. Although the diagnosis may be suspected on ultrasound by demonstrating a skull defect with adjacent soft tissue swelling, final diagnosis is rarely done on US alone.

The typical radiographic appearance of cranial involvement are ‘punched out’ osteolytic lesions without sclerotic rim nor periosteal reaction in the initial phase. Due to uneven destruction of the inner and outer cortical table, a double contour or a ‘hole in a hole’ can be seen corresponding to ‘bevelled edges’ on CT [4]. The lesions do not cross the sutures and sometimes intralesional ‘button’ sequesters are seen.

MRI is the modality of choice for the assessment of central nervous system (CNS) extension. Lesions are typically isointense to brain tissue on T1-WI, heterogeneously hyperintense on T2-WI and diffusion restriction is often noted. Enhancement is variable and sometimes enhancement of adjacent dura will be seen [4]. The final diagnosis is made by histological examination after biopsy [3].

In multifocal cranial LCH, systemic treatment is initiated if more than 2 lesions are present, lesion diameter exceeds 5 cm, or CNS risk bones are affected. CNS risk bones, like orbita or mastoid, indicate increased risk of developing diabetes insipidus or neurodegenerative CNS LCH, referring to CNS affection and development of symptoms such as dysarthria, ataxia and behavioural changes [5]. Prognosis of LCH depends on the extension of the disease, with a very good prognosis in focal disease and a mortality exceeding 50% in multisystemic dissemination under the age of 2 [6].

Written informed patient consent for publication has been obtained.

Differential Diagnosis List
Multifocal Langerhans Cell Histiocytosis
Leukaemia
Lymphoma
Lytic metastases
Dermoid cyst (orbit)
Epidermoid cyst (skull)
Multiple Myeloma (but not at this age group)
Final Diagnosis
Multifocal Langerhans Cell Histiocytosis
Case information
URL: https://www.eurorad.org/case/18242
DOI: 10.35100/eurorad/case.18242
ISSN: 1563-4086
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