An incidentaloma; not from trauma!

Clinical History

A 14-year-old female patient presented with a slowly progressive hard mass causing pain on the left side of the forehead for 1.5 years after a history of minor local trauma two years ago. She seemed to believe that her swelling started after the trauma. No other significant history or examination.

Imaging Findings

Plain skull radiograph showed a sharply demarcated radiolucent lesion with sclerotic margin, with radiating bony spicules within the lesion involving the left frontal bone. It showed a sunburst pattern.
Bone window images demonstrated a mildly expansile intradiploic osteolytic bone lesion with thin borders and characteristic sunburst / spider web pattern of trabecular thickening radiating from the centre.
On MRI the mass appeared iso to hypointense on T1WI and hyperintense on T2WI with avid post-contrast enhancement. The intracranial part of the lesion was causing compression effect on the adjacent brain parenchyma. On the outside it was producing a focal bulge of the head contour.

Discussion

Haemangiomas are benign vascular endothelial tumours that may involve any part of the body. There are two types; capillary and cavernous [1].
Their classification is based on one described by Mulliken and Glowacki. This system separates these lesions into haemangiomas and vascular malformations, depending on their natural history, histology and growth pattern.
Haemangiomas are mostly small or absent at birth. They either remain stagnant or involute over time [2].
Although found in any bone, seventy-five percent of intraosseous haemangiomas are located in the vertebral bodies (especially the thoracic spine), skull (involved outer table, normal inner table), and facial bones. Osseous haemangiomas can become clinically apparent at all ages but there is a peak at the 4th to 5th decade of life and there is a female predominance. Among all calvarial bones, the most common location is the frontal and parietal bone.
Primary osseous haemangiomas occur more frequently in the spine and less commonly in the skull. The most common location of osseous haemangioma are vertebral bodies and the second most common location is the skull, while the rests of the bones of the body are rarely affected. It can occur at all ages but peaks at 4th to 5th decade of life with female predominance. Among all calvarial bones, the parietal bone is the most commonly affected, followed by the frontal bone, occipital and temporal bones. To the best of my knowledge no case has been reported in Pakistan till now.
The best imaging modality is MRI as it gives the exact detail of the primary lesion, its soft tissue extent and associated complications [3].
T1W pre and post-contrast images as well as T2WI and fat sat sequences are acquired. These appear isointense to muscle on T1 and T2WI. They show intense homogenous enhancement on post-gadolinium images.
The information provided by imaging is vital for image-guided procedures or surgery. Imaging also helps in identifying and separating adjacent vital structures.
Mostly no therapy is recommended, even large lesions are managed conservatively. Close observation to monitor complications is recommended.
On histopathology, cavernous haemangiomas consist of a well-defined, non-encapsulated mass, composed of large fully or partially blood-filled cavernous vascular spaces, separated by scant connective tissue. Intravascular thrombosis with associated dystrophic calcification may also be seen.
Unfortunately, soft-tissue malignancies of infancy, such as fibrosarcoma or rhabdomyosarcoma, can have an imaging appearance similar to that of proliferate haemangiomas. In such ambiguous cases biopsy is mandatory to exclude malignancy.

Differential Diagnosis List

Final Diagnosis

Frontal bone intraosseous haemangioma

URL:	https://eurorad.org/case/15301
DOI:	10.1594/EURORAD/CASE.15301
ISSN:	1563-4086