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.

醫(yī)學(xué)詞匯注釋與簡要講解

carcinomatous meningitis 癌性腦膜炎

drop mets 腦脊液播散

cauda equine 馬尾

CT 平掃或增強(qiáng)均無特殊發(fā)現(xiàn)，但可以了解骨轉(zhuǎn)移

smudged 污垢狀的

myelography 脊髓造影

磁共振檢查最重要，應(yīng)包括整個神經(jīng)系統(tǒng)（顱腦和脊柱）

鑒別診斷應(yīng)圍繞不同的形態(tài)特征展開：

術(shù)后改變

癌性腦膜炎

腦脊液播散灶

神經(jīng)根/馬尾增粗

髓內(nèi)轉(zhuǎn)移

congenital hypertrophic polyradiculoneuropathies

先天性肥厚多根神經(jīng)病

chronic interstitial demyelinating polyneuropathy

慢性間質(zhì)脫髓鞘性多發(fā)性神經(jīng)病

血行轉(zhuǎn)移多來自腺癌，其次是血液?。馨土觥籽。?/p>

腦脊液播散，成人主要見于多形性膠質(zhì)母細(xì)胞瘤、而神經(jīng)母細(xì)胞瘤少見

兒童多見于胚胎性腫瘤（如髓母細(xì)胞瘤）、室管膜瘤、脈絡(luò)叢乳頭狀瘤/癌、生殖細(xì)胞腫瘤