CASE 18483 Published on 12.03.2024

Posttraumatic skull osteolysis in a child

Section

Paediatric radiology

Case Type

Clinical Case

Authors

Maja Šljivić 1, Damjana Ključevšek 2, Marko Kavčič 3,4

1 Radiology Unit, Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia

2 Department of Radiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia

3 Department of Hematology and Oncology, Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia

4 Department of Pediatrics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia   

Patient

11 years, female

Categories
Area of Interest Head and neck, Musculoskeletal bone, Paediatric ; Imaging Technique CT, MR, Ultrasound
Clinical History

An 11-year-old girl presented with a skull defect following a minor head trauma incurred from a fall two months prior. Initially, the injury manifested solely as localised swelling. No medical attention was sought. When the swelling decreased, she palpated a depression in the bone. Clinical assessment identified a painless defect in the right parietal area without neurological defects. Laboratory findings were unremarkable.

Imaging Findings

She came to our hospital for the evaluation of a skull osteolytic lesion, with a head X-ray, CT, and MRI already performed.

The head X-ray and CT revealed a well-defined lytic lesion measuring 2.5 cm across in the inner and outer table of the parietal bone without signs of sclerosis or periosteal reaction (Figure 1). The dura remained intact (Figure 2).

MRI findings included a slightly thickened dura and a well-defined, soft tissue osteolytic change in the parietal bone with a hyperintense signal on T2 weighted images, with tiny linear and punctiform signal loss (Figure 3). No evidence of soft-tissue or bone oedema was observed. The post-contrast sequence demonstrated apparent enhancement of the lesion (Figure 4). There were no intracranial abnormalities.

Ultrasound showed well-defined edges and relatively homogeneous lesion tissue with moderate perfusion. The dura and overlying subcutaneous tissue appeared intact (Figure 5).

Discussion

Background

Posttraumatic skull osteolysis is an exceedingly rare complication, with only five cases reported in the literature, predominantly in children [1–3]. It is associated with mild trauma that causes localised soft tissue swelling without neurological defects. Over the following weeks, the swelling diminishes, revealing focal bone destruction at the trauma site. The suggested pathophysiology involves a nonspecific periosteal inflammatory reaction triggered by the trauma [1].

Clinical Perspective

In all reported cases, patients presented with a history of mild trauma to the head with or without soft tissue swelling. No neurological defects or signs of infection were observed in our case or in any of the reported cases [1–3].

Given the predominantly paediatric population, non-invasive diagnostics are preferred.

Imaging Perspective

In our case, the patient was brought to the emergency trauma department, where a head X-ray was the first imaging diagnostic performed. It revealed a well-defined lytic lesion with non-sclerotic margins, affecting the inner and outer tables similarly. The CT scan offered insights comparable to the X-ray and supplementary details indicating no alterations to the dura or intracranial structures. The initial differential diagnosis considered was eosinophilic granuloma, but the absence of characteristic bevelled edges and any extra-dural or extracranial subgaleal component led us away from the diagnosis.

A subsequent head MRI conducted for further characterisation yielded nonspecific findings without signs indicating an aggressive process.

Ultrasound was performed in preparation for a potential biopsy, revealing a well-defined lesion without additional extracranial soft tissue or intracranial alterations. Given the lack of aggressive features, US was deemed the most suitable follow-up method due to its safety and efficiency.

Outcome

Differential diagnoses of skull osteolytic lesions include congenital, inflammatory, and neoplastic causes, with eosinophilic granuloma being a primary consideration. However, no signs of inflammation were present, and the imaging findings did not demonstrate the classic characteristics of eosinophilic granuloma or other neoplastic causes [4,5]. Additionally, a clinical history of mild trauma suggested a posttraumatic aetiology for the lesion.

Although some authors advocate for biopsy for definitive diagnosis [2], we opted for a watch-and-wait approach. A follow-up ultrasound a month later revealed that the lesion had shrunk (Figure 6), indicating the congenital and neoplastic causes were unlikely. No additional intervention was required [1]. Skull defect already completely ossified in the next 6 weeks following the last US. Although biopsy was not performed, we excluded other probable causes, making the diagnosis of posttraumatic lytic lesion the most likely diagnosis.

Take Home Message / Teaching Points

  • Clinical history is paramount for diagnosing posttraumatic lytic skull lesions.
  • Posttraumatic lytic skull lesions are diagnoses of exclusion.
  • Biopsy is performed in cases of unclear diagnosis and if the lesion demonstrates any aggressive characteristics.
  • Eosinophilic granuloma manifests as an osteolytic lesion with bevelled edges as well as extra- and intracranial soft-tissue components.

All patient data have been completely anonymised throughout the entire manuscript and related files.

Differential Diagnosis List
Posttraumatic lytic skull lesion
Eosinophilic granuloma
Vascular malformation
Lymphoma/leukaemia
Giant parietal foramen
Ewing sarcoma
Myofibroma
Final Diagnosis
Posttraumatic lytic skull lesion
Case information
URL: https://eurorad.org/case/18483
DOI: 10.35100/eurorad/case.18483
ISSN: 1563-4086
License