Contributed by Arnault Tauziède-Espariat, MD1, Alain Czorny, MD, PhD2, Alain Cangemi, MD3, Gabriel Viennet, MD1
1Department of Pathology, CHRU Jean Minjoz, 25030 Besançon, France
2Department of Neurosurgery, CHRU Jean Minjoz, 25030 Besançon, France
3Department of Radiology, 39100 Dole, France.
A 36-year-old man, with personal history of a right parietal cranial injury, was admitted for an evaluation of a right parietal mass that had slowly increased in the nine years prior to this presentation. General examination disclosed nothing. Skull examination revealed a palpable pulsatile and soft swelling. Routine laboratory tests were unremarkable. Computed tomography (CT) and magnetic resonance imaging (MRI) of the head were obtained to delineate the large mass in the parietal region. MRI showed a prominent extracranial scalp vein in direct communication with the superior sagittal sinus, through a right parietal bone defect. CT scan showed an old fracture with osteomeningeal breach. There was no parenchymal abnormality. The lesion was heterogeneously intense on T2- (Figure 1), T2-Flair (Figure 2) and T1-weighted images (Figure 3). Doppler sonography found vascular structures composing this lesion. Due to the worsening pain at the site of her swelling, a total resection was performed. Intra-operatively, the lesion was defined by the surgeon as a blood-filled sac within the pericranium and directly overlying the bone suggesting an angioma.
Histopathological examination evidenced a dense fibrous tissue containing in one hand a proliferation of small vessels surrounded by skeletal muscle fibers and in other hand dilated thin endothelial-lined veins (Figure 4). These vessels crossed the diploe (Figure 5). The orcein stain sowed elastic fibers in the wall of some vessels (Figure 6). Bony changes are present with osteolysis. Face to this proliferation, the epicranium presented a reactive fibrosis in the dermis. Large dilated vessels were present in the subcutaneous tissue. Immunohistochemical analysis by anti-CD31 and anti-CD34 (Figure 7) confirmed the presence of endothelium. Stains for actin (Figure 8) confirmed the absence of muscular layer in abnormal vessels.