Hemangiomas refer to benign vascular tumour-like lesions found within skin and mucus membranes. Traditionally they are used to refer to neoplastic lesions alone, however non-neoplastic vascular malformations such has cavernous hemangiomas have also been included in this definition. They are classified into capillary, cavernous, mixed and cellular (1). Capillary hemangiomas are characterised by nodules of capillaries lined by flattened endothelium (2). These lesions are most often found within the skin and subcutaneous soft tissue, and very few reports describe their occurrence in the central nervous system (2). Due to the rarity of this type of lesion, there is insufficient data analysing their growth rate and natural history in the CNS, and no guidelines on their management (3).
We carried out a literature search using the terms (capillary hemangioma) AND (intracranial OR brain OR nervous system) to include case reports, case series, reviews and meta-analyses, which produced a result of 281 articles. Abstracts were analysed and 27 of these papers were included as pertaining to intracranial capillary hemangiomas, which included a total of 32 diagnosed cases of which 17 in paediatric patients, and 15 in adults (see Tables 1 and 2). There was a wide age range from 0 to 79 years. A majority of patients (N = 17, 53%) were children below age 15, including 7 patients (22.9%) being less than a year old. A majority of these lesions were extra-axial and occurring in variable locations, most commonly the cavernous sinus (N = 6, 18.8%), followed by skull base and convexity regions. Three patients had multiple intracranial lesions (4–6), of which one was a child with widespread neurocutaneous capillary hemangiomas (4). Only 4 cases of capillary hemangiomas were intra-axial (4–8). Lesions diagnosed in newborns were giant in a majority (N = 3, 60%) of cases of newborn capillary hemangiomas, and presented with features of raised intracranial pressure (ICP) (9–11). Only one other patient aged 3 was diagnosed with a giant lesion (12). In older children and in adults, headache and associated symptoms of raised ICP were the commonest presenting feature, followed by seizures and cranial nerve palsies. Of the 30 patients whose treatment was discussed in the paper, a majority (N = 17, 56.7%) were managed with complete resection of the tumour, usually en bloc. Five patients had partial resection with or without stereotactic radiosurgery (SRS), two had SRS alone and five had biopsy alone (see Table 3). No patient with complete excision or stereotactic radiosurgery had recurrence following a year. On the other hand, 60% of patients who underwent biopsy alone or partial resection with at least one year of follow up showed recurrence.
Propranolol, a medication used first line for cutaneous capillary hemangiomas has also been applied to intracranial capillary hemangioma in a single case alone (9). In this case, the patient, a neonate with a presumed giant posterior fossa capillary hemangioma based on detailed radiology assessment alone, was treated with propranolol for 6 months (9). Complete tumour regression was seen at one year post-treatment. Limited evidence suggests that complete surgical resection or SRS alone or in combination with surgery may be curative, however medical treatments including propranolol should also be further evaluated for their role in treating intracranial capillary hemangiomas.
Benign capillary hemangiomas are radiologically and histologically distinct from most other vascular tumours occurring in the CNS, although their clinical presentation may be similar. Cavernous hemangiomas consist of enlarged, dilated vessels, unlike the tightly packed capillary-sized vessels seen with capillary hemangiomas. They are often thrombosed with perivascular hemosiderin deposition and calcification. Radiologically, they occur intra-axially and display a characteristic popcorn like appearance on MRI (6). Clearer evidence exists from systematic reviews and meta-analyses as to their natural history and management compared to capillary hemangiomas (13). Capillary telangiectasia of the CNS is also a type of capillary ectasia, however this is characterised histologically by neural parenchyma interspersed between ectatic vessels rather than the closely packed and lobular pattern seen with capillary hemangiomas. Radiologically they are intraparenchymal, usually found in the pons, lack clear demarcation and display a characteristic “brush” or “stipple”- like enhancement (14). They are most often asymptomatic and may be managed conservatively in a large majority of cases.
It is often difficult to radiologically distinguish these lesions from meningiomas, hemangiopericytomas and other vascular dural-based lesions of the CNS. In our literature review, we found most lesions were initially misdiagnosed as meningiomas from the radiological appearance. Hemangiopericytomas may also appear radiologically similar to capillary hemangiomas with their extra-axial location, dural attachment and vivid enhancement with intralesional signal voids, however they are different histological entities. They arise from fibroblast cells, are highly mitotic and cellular on histology, and classically express STAT-6 antibodies. Clinically, there is a risk of local invasion of bone and distant metastases to liver, lung or bone (15).