Imaging Diagnosis —Antemortem Detection of Oligodendroglioma “Cerebrospinal Fluid Drop Metastases” in a Dog by Serial Magnetic Resonance Imaging

Abstract

An English Bulldog underwent radiation therapy of an intracranial, left lateral ventricle mass. Following resolution of the primary mass, an intraventricular fourth ventricle lesion developed. Subsequently, multiple lesions developed from the cervical central canal and leptomeninges. Serial magnetic resonance imaging documented the propagation of lesions along the cerebrospinal fluid (CSF) pathways, known as "CSF drop metastasis." Histopathology confirmed multifocal intraventricular and leptomeningeal oligodendroglioma. Oligodendroglioma should be included in the differential diagnosis for an intraventricular tumor exhibiting apparent CSF drop metastasis.

Anaplastic oligodendroglioma with leptomeningeal dissemination in a french bulldog

“…Oligodendrogliomas are the second most common primary brain tumors in dogs [ 23 , 24 , 28 ], with certain brachycephalic breeds, such as French Bulldogs, Boxers, and Boston Terriers, being particularly susceptible [ 6 , 23 , 24 , 28 ]. There have been several histological reports of oligodendrogliomas extending through the ependyma and along the cerebrospinal fluid (CSF) pathway [ 14 , 21 , 30 ]; however, detailed descriptions of the use of RT and/or chemotherapy in individual cases are very limited [ 30 ]. Here, we describe the case of a dog with anaplastic oligodendroglioma that exhibited leptomeningeal dissemination and hydrocephalus despite treatment of the isolated mass with megavoltage RT and chemotherapy with lomustine.…”

“…In veterinary medicine, meningeal enhancement has also been reported in CSF drop metastasis [ 30 ]. Dissemination within the ventricular system, including the central canal, along with local invasion into or widespread metastases to the meninges is recognized in canine anaplastic oligodendrogliomas [ 28 ], though clinical reports are few [ 14 , 21 , 30 ]. Peritumoral nuclear atypia and multiple large-walled vessels are often found in anaplastic oligodendrogliomas [ 28 ].…”

“…Local expansion from the primary site with spread into the adjacent subarachnoid space in the meninges and the ventricular system can occur. During CSF drop metastasis, the tumor extends through the ependyma and along the CSF pathway, and new lesions develop in a caudal direction, accompanied by the formation of tumor masses [ 14 , 28 , 30 ]. Leptomeningeal dissemination of oligodendroglioma and anaplastic oligodendroglioma has rarely been reported in humans [ 20 , 25 ].…”

“…Several veterinary reports have documented the results and prognosis of gliomas treated with RT [ 1 , 2 , 10 , 30 ] and chemotherapy [ 5 , 7 , 8 , 10 , 11 , 29 ]. In one case, an oligodendroglioma was effectively reduced in size after RT (stereotactic ablative RT), though a new mass suspected as CSF drop metastasis was observed 5 weeks after therapy [ 30 ]. Although reduction of the new mass was observed following the second RT, ventral leptomeningeal enhancement had extended, and cervical lesions were observed [ 30 ].…”

“…In one case, an oligodendroglioma was effectively reduced in size after RT (stereotactic ablative RT), though a new mass suspected as CSF drop metastasis was observed 5 weeks after therapy [ 30 ]. Although reduction of the new mass was observed following the second RT, ventral leptomeningeal enhancement had extended, and cervical lesions were observed [ 30 ]. In another case of anaplastic oligodendroglioma treated with RT (hypofractionated RT), the mass showed significant regression 2 months post-therapy, though clinical worsening and lesion regrowth was observed 4 months after RT [ 10 ].…”