Abstract
Objectives Ecchordosis physaliphora (EP) is a benign notochord lesion of the clivus arising
from the same cell line as chordoma, its malignant counterpart. Although usually asymptomatic,
it can cause spontaneous cerebrospinal fluid (CSF) rhinorrhea. Benign notochordal
cell tumor (BNCT) is considered another indolent, benign variant of chordoma. Although
aggressive forms of chordoma require maximal safe resection followed by proton beam
radiotherapy, BNCT and EP can be managed with close imaging surveillance without resection
or radiotherapy. However, while BNCT and EP can be distinguished from more aggressive
forms of chordoma, differentiating the two is challenging as they are radiologically
and histopathologically identical. This case series aims to characterize the clinicopathological
features of EP and to propose classifying EP and BNCT together for the purposes of
clinical management.
Design Case series.
Setting Tertiary referral center, United Kingdom.
Participants Patients with suspected EP from 2015 to 2019.
Main Outcome Measures Diagnosis of EP.
Results Seven patients with radiological suspicion of EP were identified. Five presented
with CSF rhinorrhea and two were asymptomatic. Magnetic resonance imaging features
consistently showed T1-hypointense, T2-hyperintense nonenhancing lesions. Diagnosis
was made on biopsy for patients requiring repair and radiologically where no surgery
was indicated. The histological features of EP included physaliphorous cells of notochordal
origin (positive epithelial membrane antigen, S100, CD10, and/or MNF116) without mitotic
activity.
Conclusion EP is indistinguishable from BNCT. Both demonstrate markers of notochord cell lines
without malignant features. Their management is also identical. We therefore propose
grouping EP with BNCT. Close imaging surveillance is required for both as progression
to chordoma remains an unquantified risk.
Keywords
ecchordosis physaliphora - EP - chordoma - proton beam radiotherapy - BNCTs - benign
notochordal cell tumors
