Figure 1
Teaching Case
SectionNeuroradiology
Case TypeClinical Cases
AuthorsDr Praveen P Wali, Dr Harsha Chadaga, Dr Anil R, Dr Madhukumar
Connected authors
52 years, male
52-year-old male patient, doctor by profession, with persistent headache for one year. MRI performed outside was unremarkable except for incidental retroclival arachnoid cyst. He came for follow-up imaging with no fresh complaints. He chose to come for follow-up because he was more anxious due to his profession.
Retroclival ecchordosis physaliphora
Retroclival arachnoid cyst
Retroclival epidermoid
A well-defined 10 x 5.8 mm T2 hyperintense lesion which followed CSF signal intensity on all sequences was seen in pre-pontine cistern to the left of the basilar artery. Another similar lesion measuring 11.2 x 7.2 mm was seen to the right of midline in the prepontine cistern. It was likely that these two communicate in the midline. There were tiny T2 hyperintense lesions in the dorsal clivus similar in signal intensity to that of the retroclival lesion. The retroclival lesion was connected to the dorsal clival lesions through a stalk.
Background:
Ectopic location of remnants of notochordal tissue in posterior wall of clivus [1, 2] was described by Lushka. Differentials considered for notochordal remnant derived mass in retro-clival location: ecchordosis physaliphora, benign notochordal cell tumours and neuroenteric cyst (both benign) or chordomas (malignant) [3, 4].
Clinical Perspective:
Notochordal development begins in 3rd week of intra-uterine life and forms the primitive skeleton of vertebrates [5, 11]
The adult counterpart of notochordal remnant is the nucleus pulposus of the intervertebral disc. Occasional locations of notochordal rests are craniospinal axis, sacrococcygeal, dorsum of sella and clival region [1, 2]
Ecchordosis-physaliphora is a rare benign gelatinous and hamartomatous tissue, typically situated intradurally and mostly attached to the dorsal clivus with a delicate pedicle. [6, 7] Rarely it can be located in the sacrococcygeal region. [2, 8] The intracranial location is within the subdural and subarachnoid space in the prepontine cistern attached to the dorsal clivus by a pedicle and associated with bony defect [9, 13, 14]
It is usually asymptomatic due to small size and slow growth. [2] Incidence is ~0.4-2% at autopsies. [1, 2] Symptomatic Ecchordosis physaliphora are very rare and only few cases reported, usually due to expansion and mass effect on adjacent structures and sometimes extratumoral haemorrhage. [16, 17, 18]
Histologic, immunohistochemistry and ultrastructural studies are often ineffective in distinguishing small samples of Ecchordosis physaliphora and chordomas [1, 2]
Imaging Perspective: In MRI Ecchordosis physaliphora appears as well-circumscribed extra-axial non-enhancing lesion in prepontine cistern. Hypointense on T1WI, hyperintense on T2WI. [16, 19] In contrast, chordomas usually enhance. [11, 12, 15] Even intradural chordomas show considerable enhancement. [10] Hence, it is postulated that if the lesion enhances, it usually represents an extradural/intradural chordoma, while a non-enhancing lesion represent an Ecchordosis physaliphora. [12] However, T1-hyperintensity and non-enhancement points towards another benign condition i.e., neuroenteric cyst. [12, 13, 19] Benign notochordal cell tumours are T1-hypointense, homogenously iso-hyperintense on T2-sequence. There should be no or minimal enhancement, however, no extra-osseus extension of lesion should be seen. [16] The presence of an osseus stalk connecting the retroclival mass with the clival notochordal remnant is a characteristic hallmark of Ecchordosis physaliphora. [1, 16]
Other differential diagnoses include dermoid, epidermoid, arachnoid-cyst. Arachnoid cysts are of CSF signal on all sequences, sharp marginated homogeneous unilocular masses. Epidermoid cysts are ill-defined, located at cerebellopontine angle cistern and reveal characteristic diffusion restriction. Dermoids are heterogeneous extra-axial masses containing fat/calcification and located in midline. [15, 20, 21] CT is not advisable for diagnosis due to posterior fossa artefacts and also lesion density is almost similar to that of CSF [22]. However, to demonstrate bony defects CT can be performed, but most often MRI does reveal bony defects as well.
Conclusion: Since a benign entity like Ecchordosis physaliphora shares significant similarity histologically with malignant ones like clival chordoma, diagnosis is challenging and this differentiation is extremely essentially as treatment differs significantly. Imaging modalities like MRI and CT scans aid in identifying and distinguishing these lesions.
Ectopic location of remnants of notochordal tissue in posterior wall of clivus [1, 2] was described by Lushka. Differentials considered for notochordal remnant derived mass in retro-clival location: ecchordosis physaliphora, benign notochordal cell tumours and neuroenteric cyst (both benign) or chordomas (malignant) [3, 4].
Clinical Perspective:
Notochordal development begins in 3rd week of intra-uterine life and forms the primitive skeleton of vertebrates [5, 11]
The adult counterpart of notochordal remnant is the nucleus pulposus of the intervertebral disc. Occasional locations of notochordal rests are craniospinal axis, sacrococcygeal, dorsum of sella and clival region [1, 2]
Ecchordosis-physaliphora is a rare benign gelatinous and hamartomatous tissue, typically situated intradurally and mostly attached to the dorsal clivus with a delicate pedicle. [6, 7] Rarely it can be located in the sacrococcygeal region. [2, 8] The intracranial location is within the subdural and subarachnoid space in the prepontine cistern attached to the dorsal clivus by a pedicle and associated with bony defect [9, 13, 14]
It is usually asymptomatic due to small size and slow growth. [2] Incidence is ~0.4-2% at autopsies. [1, 2] Symptomatic Ecchordosis physaliphora are very rare and only few cases reported, usually due to expansion and mass effect on adjacent structures and sometimes extratumoral haemorrhage. [16, 17, 18]
Histologic, immunohistochemistry and ultrastructural studies are often ineffective in distinguishing small samples of Ecchordosis physaliphora and chordomas [1, 2]
Imaging Perspective: In MRI Ecchordosis physaliphora appears as well-circumscribed extra-axial non-enhancing lesion in prepontine cistern. Hypointense on T1WI, hyperintense on T2WI. [16, 19] In contrast, chordomas usually enhance. [11, 12, 15] Even intradural chordomas show considerable enhancement. [10] Hence, it is postulated that if the lesion enhances, it usually represents an extradural/intradural chordoma, while a non-enhancing lesion represent an Ecchordosis physaliphora. [12] However, T1-hyperintensity and non-enhancement points towards another benign condition i.e., neuroenteric cyst. [12, 13, 19] Benign notochordal cell tumours are T1-hypointense, homogenously iso-hyperintense on T2-sequence. There should be no or minimal enhancement, however, no extra-osseus extension of lesion should be seen. [16] The presence of an osseus stalk connecting the retroclival mass with the clival notochordal remnant is a characteristic hallmark of Ecchordosis physaliphora. [1, 16]
Other differential diagnoses include dermoid, epidermoid, arachnoid-cyst. Arachnoid cysts are of CSF signal on all sequences, sharp marginated homogeneous unilocular masses. Epidermoid cysts are ill-defined, located at cerebellopontine angle cistern and reveal characteristic diffusion restriction. Dermoids are heterogeneous extra-axial masses containing fat/calcification and located in midline. [15, 20, 21] CT is not advisable for diagnosis due to posterior fossa artefacts and also lesion density is almost similar to that of CSF [22]. However, to demonstrate bony defects CT can be performed, but most often MRI does reveal bony defects as well.
Conclusion: Since a benign entity like Ecchordosis physaliphora shares significant similarity histologically with malignant ones like clival chordoma, diagnosis is challenging and this differentiation is extremely essentially as treatment differs significantly. Imaging modalities like MRI and CT scans aid in identifying and distinguishing these lesions.
References
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[9] Nishiguchi T, Mochizuki K, Tsujio T, Nishita T, Inoue Y. (2010) Lumbar vertebral chordoma arising from an intraossious benign notochordal cell tumour: radiological findings and histopathological description with a good clinical outcome. BRITISH JOURNAL OF RADIOLOGY 83:e49-e54 (PMID: 20197427)
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[11] Yamaguchi T, Yamato M, Saotome K (2002) First histologically confirmed case of a classic chordoma arising in a precursor benign notochordal lesion: differential diagnosis of benign and malignant notochordal lesions. Journal of Skeletal Radiology 31:413-418 (PMID: 12107574)
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[13] Chauvel A, Taillat F, Gille O, et al (2005) Giant vertebral notochordal rest: a new entity distinct from chordoma. Histopathology 47:646-649 (PMID: 16324209)
[14] Nishiguchi T, Nakayama T, Mochizuki K, et al (2008) Incidental spinal osteosclerotic lesions: a pictorial review. Journal of European Radiology S547-S602
[15] Kyriakos M, Totty GW, Lenke GL (2003) Giant vertebral notochordal rest: a lesion distinct from chordoma: discussion of an evolving concept. American Journal of Surgical Pathology 27:396-406 (PMID: 12604898)
[16] Corsi A, De Maio F, Mancini F, Ippolito E, Riminucci M, Bianco P (2008) Notochordal inclusion in the vertebral bone marrow. Journal of Bone and Mineral Research 23:572-575 (PMID: 18072879)
[17] Boriani S, Bandiera S, Biagini R, et al (2006) Chordoma of the mobile spine: fifty years of experience. Spine (Phila Pa 1976) 31:493-503 (PMID: 16481964)
[18] Yamaguchi T, Watanabe-Ishiiwa H, Suzuki S, Igarashi Y, Ueda Y. (2005) Incipient chordoma: a report of two cases of early-stage chordoma arising from benign notochordal cell tumors. Modern Pathology 18:1005-1010 (PMID: 15803192)
[19] Haasper C, Länger F, Rothenthal H, et al (2007) Coccydynia due to a benign notochordal cell tumor. Spine 32:E394-E396. (PMID: 17572612)
[20] Erdem E, Angtuaco EC, Van Hemert R, Park JS, Al-Mefty O (2003) Comprehensive review of intracranial chordoma. Radiographics 23:995-1009 (PMID: 12853676)
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Case information
| URL: | https://eurorad.org/case/14846 |
| DOI: | 10.1594/EURORAD/CASE.14846 |
| ISSN: | 1563-4086 |
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