Intradural Metastases 硬脑膜转移瘤

Key Facts

In adults,intradural ＜＜extradural spinal metastases(Leptomeningeal ＞＞cord metastases).

In children,intradural ＞extradural metastases.

Classic imaging appearance=“carcinomatous meningitis”

can be caused by spread from intracranial neoplasm(“drop mets”)or non-CNS primary tumor.

Imaging Findings

General features

Best imaging clue:smooth/nodular enhancement along cord,roots.

Four basic patterns:(1)Diffuse,thin,sheetlike coating of cord/roots (“carcinomatous meningitis”)；(2)multifocal discrete nodules along cord/roots；

(3)“rope-like” thickening of cauda equine；(4)solitary focal mass at bottom of thecal sac or intramedullary nodule.

CT findings:often normal；+/-bony/extradural tumor present.

MR findings

T1WI:(1)Metastases usually isointense with cord,roots；(2)extensive disease may fill thecal sac (see Lymphoma illustration)；(3)CSF in sac has “ground glass” appearance；(4)nerve roots appear blurred,“smudged”.

T2WI:Metastases usually isointense with cord,roots (hypointense to CSF).

Contrast-enhanced T1WI:(1)Strong enhancement；(2)pattern varies including“sugar coating” of cord and/or roots,single/multiple enhancing nodular masses,and round/ovoid intramedullary mass,often with ring-like pattern.

Myelography,CT myelography:(1)Single or multifocal nodules；(2)expanded cord,thickened nerve roots.

Imaging recommendations

Image entire neuraxis!

High resolution T2WI,contrast-enhanced,fat-suppressed T1WI and STIR(look for bony metastases).Do it prior to craniotomy!

Differential diagnosis

Postoperative change:Subarachnoid blood,adhesions can mimic leptomeningeal metastases.

“Carcinomatous meningitis”:Pyogenic meningitis (clinical/laboratory findings helpful),sarcoidosis.

“Drop Metastases”:Multifocal primary tumor,myxopapillary ependymoma,hemangioblastoma,astrocytoma (uncommon).

Thick nerve roots/Cauda equina:Congenital hypertrophic polyradiculoneuropathies,Charcot-Marie-Tooth,dejerine-sottas,chronic interstitial demyelinating polyneuropathy (CIDP),chemotherapy-associated polyneuropathy,AIDS-associated polyneuropathy (e.g.,CMV).

Intramedullary metastases(rare):Radiation-induced myelitis,primary cord tumor (metastases=focal nodule+edema ＞infiltrating mass).

Pathology

General path comments:Broad spectrum of primary neoplasms.

Etiology-pathogenesis

Hematogenous dissemination from extracranial neoplasm:Most are adenocarcinomas (lung,breast).

Other=non-Hodgkin lymphoma,leukemia.

“Drop” metastases from CNS primary tumor:(1)Adults=anaplastic astrocytoma,glioblastoma GBM (0.5%-1% of cases)；(2)Children=embryonal tumor (medulloblastoma),ependymoma,choroid plexus tumors (both papillomas,carcinomas),germinomas.

Gross pathologic-surgical features and microscopic features

Varies with pattern,type of metastasis.

Varies with histology of primary neoplasm；CSF usually positive in leptomeningeal metastases disease and negative in intramedullary tumors.

Clinical issues

Presentation is varies；may be asymptomatic early.Radiculopathy ＞myelopathy.

Natural history:relentless progression typical.

Treatment:radiation and/or chemotherapy.

Prognosis:survival usually ＜1 year.

医学词汇注释与简要讲解

carcinomatous meningitis 癌性脑膜炎

drop mets 脑脊液播散

cauda equine 马尾

CT 平扫或增强均无特殊发现，但可以了解骨转移

smudged 污垢状的

myelography 脊髓造影

磁共振检查最重要，应包括整个神经系统（颅脑和脊柱）

鉴别诊断应围绕不同的形态特征展开：

术后改变

癌性脑膜炎

脑脊液播散灶

神经根/马尾增粗

髓内转移

congenital hypertrophic polyradiculoneuropathies

先天性肥厚多根神经病

chronic interstitial demyelinating polyneuropathy

慢性间质脱髓鞘性多发性神经病

血行转移多来自腺癌，其次是血液病（淋巴瘤、白血病）

脑脊液播散，成人主要见于多形性胶质母细胞瘤、而神经母细胞瘤少见

儿童多见于胚胎性肿瘤（如髓母细胞瘤）、室管膜瘤、脉络丛乳头状瘤/癌、生殖细胞肿瘤