Radiological Diagnosis of a Rare Prepontine Lesion: Ecchordosis Physaliphora

Abstract

Ecchordosis physaliphora (EP) is a notochordal remnant tissue rarely encountered during routine clinical practice. These lesions usually do not produce any significant symptoms as they are slow-growing and mostly small in size. Symptoms are due to mass effects on adjacent structures when they are large or extra-tumoral hemorrhage. Because of histological similarity with chordoma, diagnosis is challenging, and this differentiation is essential as the disease course and treatment differ significantly. Imaging plays a crucial role in identifying and distinguishing these lesions. We report the case of a 16-year-old male who presented with intermittent headache and neck pain for six months. His routine clinical examinations were within normal limits. On neurological assessment, there was no focal neurodeficit. Evaluation of cranial nerves did not reveal any evidence of palsy. Routine hematological tests were also normal. A computed tomography (CT) scan of the brain revealed a mass in front of the pons. Magnetic resonance imaging (MRI) for further evaluation revealed a T1 hypointense and T2/fluid-attenuated inversion recovery hyperintense lesion in the pre-pontine cistern. There was no enhancement in the mass either in the post-contrast CT or MRI scans. There was no bony erosion and clivus was normal. Based on the location and characteristic imaging features, a diagnosis of EP was made. There may be several other lesions that may present as a mass in the pre-pontine region. Histopathological tests may find it difficult to distinguish between lesions that originate from notochord remnants. Imaging studies play a vital role in confirming the diagnosis and help in planning treatment and follow-up.

Imaging of the Craniocervical Junction: A Pictorial Review

“…EP is typically located in the prepontine region at the retroclival midline where it is attached to the posterior wall of the clivus with a small pedicle, in close proximity to the basilar artery. 59,60 CT reveals a well-delineated radiolucent clival defect. Presence of an osseous stalk is pathognomonic.…”

“…Presence of an osseous stalk is pathognomonic. 59,60 On MRI, EP is a well-circumscribed, round, extra-axial lesion that is hypointense on T1-weighted images and hyperintense on T2-weighted images (►Fig. 14 and ►Fig.…”

Symptoms: Headaches, Aural Pressure, and Dizziness

“…Thus, the aforementioned differential diagnoses were ruled out. Instead, these findings appear suggestive of a hamartomatous mass termed ecchordosis physaliphora (EP) or of a cystic lesion, such as an epidermoid (skin) cyst 1 . A hamartomas is primarily a benign mass of disorganized tissue native to a particular anatomical location.…”

“…EP describes a benign neoplasm derived from ectopic notochordal remnants 1–4 . They have a gelatinous consistency and have been found along the midline craniospinal axis from the clivus (bone in front of the brainstem) to the sacrococcygeal region.…”

Letter: Chordoma and Ecchordosis Physaliphora: 2 Sides of the Same Coin

“…Each year, 1 person in a million is diagnosed with chordoma, but only 45 cases of EP have been reported. [1][2][3][4][5][6][7][8][9][10][11][12] In 1857, Virchow invented the acronym EP for the newly discovered dorsum sella lesion, believing it was cartilage related. A year later, Muller discovered notochord rests in the synchondrosis sphenooccipitalis and hypothesized that these were the source of the EP dorsum sella masses.…”