Traumatic enlargement of an intradiploic cavernous hemangioma.

Sir,

A 15-year-old male, who had prominent inion since early childhood, presented with fall on occiput followed by transient loss of consciousness to our emergency department. Neurological examination was normal, except a nontender unduely prominent inion. Axial computed tomography (CT) revealed a focal bony swelling at the external occipital protuberance, without any parenchymal abnormality [Figure 1a]. Biopsy of the lesion was advised, but patient and relatives ignored the medical advice. Patient reported to us after 18 months when he developed severe occipital headache on lying supine. The pain forced him to sleep in lateral postures only. Local examination revealed tenderness and significant increase in size of swelling at the external occipital protuberance measuring 7 × 6 × 6 cm in size. Neurological examination was normal. CT brain showed an expansile lytic lesion involving the occipital bone having a coarse bony matrix and radiating spicules. There was erosion of both inner and outer tables of skull [Figure 1b]. Magnetic resonance imaging (MRI) revealed a T2 heterogeneously hyperintense, T1 isointense, and intensely enhancing mass with intracranial extradural extension. A large soft tissue component in the scalp was also present [Figure 1cߝe]. Surgical excision of the lesion was done with margin of surrounding normal bone. The lesion was intradiploic in location with expansion of outer and inner tables of skull. The underlying dura was intact, however, mass effect on venous sinuses was present. Careful preservation of the torcula and venous sinuses was done. The bone defect was filled with appropriately tailored bone cement. Histopathology revealed anastomosing, mainly thin-walled vascular channels lined by a single layer of flattened to plump endothelial cells. The tumor cells were seen amidst the bony trabeculae. These findings were suggestive of intraosseous cavernous hemangioma [Figure 2]. Postoperatively, patient was relieved of his pain and was able to lie supine comfortably. Follow-up CT of head showed complete excision of the lesion without recurrence [Figure 1f].

Figure 1

(a) Axial plain CT shows a focal bony swelling at the external occipital protuberance. (b) Axial CT reveals gross enlargement of the lesion showing an expansile lytic tumor involving the occipital bone with a coarse bony matrix. Erosion of inner and outer table of skull vault is present. (c) Axial T2-weighted MRI shows a heterogeneously hyperintense lesion with hypointense borders. (d) Unenhanced sagittal T1-weighted MRI shows a hypointense lobulated mass which shows (e) intense post-contrast enhancement. (f) Follow-up CT shows complete excision without recurrence. CT = Computed tomography, MRI = magnetic resonance imaging

Figure 2

Photomicrograph shows anastomosing, mainly thin-walled vascular channels lined by a single layer of flattened to plump endothelial cells amidst the bony trabeculae (hematoxylin and eosin (H and E), ×400)

Primary intraosseous hemangiomas are uncommon bony tumors with an incidence of 0.7-1%[1] with majority occurring in the calvaria and vertebrae. Frontal and parietal bones are common location in the skull with a female preponderance. Occipital location is very rarely reported with these benign bony vascular lesions.[1] Cavernous type is commoner in skull than capillary hemangiomas, which is frequently seen in vertebral column.[2] These commonly manifest clinically during adulthood unlike capillary hemangiomas of infancy and childhood, which are visible on the surface. The giant lesions are more than 5 cm in size.

Etiology is believed to be congenital origin or previous trauma.[2] These arise from vessels present in the intradiploic space and derive their blood supply from the branches of external carotid system such as middle meningeal and superficial temporal artery.[2]

These grow slowly and present with pain at the local site and visible or palpable swelling over the head.[3] Other symptoms are referable to the site of their occurence. The major clinical problem associated with these tumors is blood steal from brain parenchyma and resultant atrophy and mental retardation. Other may be congestive heart failure and thrombocytopenia known in this setting as Kasabach–Merritt syndrome.[1234] Our patient had posttraumatic enlargement of the lesion, which was initially very small. We believe that the role of trauma in etiopathogenesis is controversial. The trauma may be attention drawing to asymptomatic lesion or may cause enlargement by intratumoral bleed.

The imaging appearance of calvarial hemangiomas can be characteristic. On plain radiographs, they show sunburst of radiating trabeculae having peripheral sclerotic rim.[1] This is due to gradual erosion of surrounding bone as they grow. On CT, calvarial hemangiomas are lytic lesions with multiple interposed trabeculae. On MRI, these lesions are hyperintense on T1- and T2-weighted imaging (WI) with intense post-contrast enhancement. However, the intensity on T1-WI is variable depending upon the presence of fat.[1]

The common differentials include aneurysmal bone cyst, giant cell tumor, Langerhans’ cell histiocytosis, sarcoma, meningioma, metastatic disease, and dermoid tumor.[3]

Complete surgical excision is the treatment of choice.[4] Most important goal at the time of surgery is control of bleeding. Preoperative embolization is one option. Other strategy is excision of the tumor with surrounding rim of normal bone without entering into the tumor.

Intradiploic hemangioma of the occipital bone is a rare bony vascular tumor. Giant hemangiomas of this region with traumatic enlargement have rarely been reported.