Pathological Evaluation of Radiation-Induced Vascular Lesions of the Brain: Distinct fromDe NovoCavernous Hemangioma

Abstract

PurposeWe aimed to evaluate the histologic and radiologic findings of vascular lesions after stereotactic radiosurgery (SRS) categorized as radiation-induced cavernous hemangioma (RICH).Materials and MethodsAmong 89 patients who underwent neurosurgery for cavernous hemangioma, eight RICHs from 7 patients and 10 de novo CHs from 10 patients were selected for histopathological and radiological comparison.ResultsHistologically, RICHs showed hematoma-like gross appearance. Microscopically, RICH exhibited a hematoma-like area accompanied by proliferation of thin-walled vasculature with fibrin deposits and infiltrating foamy macrophages. In contrast, CHs demonstrated localized malformed vasculature containing fresh and old clotted blood on gross examination. Typically, CHs consisted of thick, ectatic hyalinized vessels lined by endothelium under a light microscope. Magnetic resonance imaging of RICHs revealed some overlapping but distinct features with CHs, including enhancing cystic and solid components with absence or incomplete popcorn-like appearance and partial hemosiderin rims.ConclusionTogether with histologic and radiologic findings, RICH may result from blood-filled space after tissue destruction by SRS, accompanied with radiation-induced reactive changes rather than vascular malformation. Thus, the term "RICH" would be inappropriate, because it is more likely to be an inactive organizing hematoma rather than proliferation of malformed vasculature.

MR imaging findings in some rare neurological complications of paediatric cancer

“…On MRI, RIFHD shows mixed intensity with an enhancing cystic and/or solid component and an incomplete haemosiderin rim, which would be insufficient for a diagnosis of de novo cavernous malformation [ 54 ]. Small RIFHD lesions are best seen on iron-sensitive sequences such as gradient recalled echo imaging or susceptibility weighted imaging [ 48 ] (Fig.…”

Radiation-induced vascular malformations in the brain, mimicking tumor in MRI-based treatment response assessment maps (TRAMs)

“…RICMs mostly develop in the pediatric population [6] , but are also observed in adults. In a literature search from 2006 by Nimjee et al [7] , 76 cases of RICMs were found.…”

Pseudocavernoma—a new diagnosis?

“…Imaging characteristics of pseudocavernomas sometimes deviate from that of CMs. Cha et al compared eight pseudocavernomas to ten de novo CMs unrelated to radiation [3]. They found that all pseudocavernomas showed enhancement, which is not the case for CMs.…”

“…Baumgartner et al reported three patients with CM-like lesions that developed after radiotherapy, and in all patients the diagnosis CM was radiologically and histopathologically confirmed [2]. In contrast, Cha et al reported seven patients with CM-like lesions that developed after radiosurgery, and all were histopathologically incompatible with CMs and thus representing pseudocavernomas [3].…”

“…This is in line with our rare observation of a Bchronic hematoma^at the site of AVMs treated with radiosurgery many years earlier. Furthermore, others have suggested that radiation-induced damages can mimic CMs [3,12], and we thus changed our manuscript accordingly.…”