Chordoma dedifferentiation after proton beam therapy: a case report and review of the literature

Abstract

BackgroundChordoma is a rare invasive bone tumor that may occur anywhere along the neuraxis. A total of three primary histological varieties have been identified: conventional, chondroid, and dedifferentiated.Case presentationWe report a case of an 8-year-old white girl who presented with conventional chordoma, was treated with surgical resection and mixed proton and photon beam therapy, and had a recurrence in the resection cavity 2.5 years later with dedifferentiated morphology. The recurrent tumor did not express brachyury, a recently identified protein specific to tissue of notochordal origin.ConclusionsThe short time period between radiation therapy and dedifferentiation, low dose of photons, and rarity of dedifferentiated skull base chordomas in pediatric patients should alert clinicians to the possibility of chordoma dedifferentiation after proton beam therapy.

Peculiar pathological, radiological and clinical features of skull‐base de‐differentiated chordomas. Results from a referral centre case–series and literature review

“…In particular, the similar clinical presentation and the presence of a sarcomatous component – composed of pleomorphic or spindle cell sarcoma or, rarely, osteosarcoma – observed in a recurrent or initial tumour after radiation therapy make differential diagnosis between DC and sarcomatous chordoma difficult. The presence of a transitional feature between the conventional chordoma and the sarcomatous component, and the immunoreactivity for brachyury, pan‐cytokeratin and/or EMA in both tumour components, allowed us to distinguish this aggressive chordoma variant, which has also been reported in the literature as chordoma with predominant ‘spindling of the epithelial cells’ or ‘sarcomatoid chordoma’ . Conversely, poorly differentiated chordoma has a distinct clinical, morphological and immunohistochemical profile compared to DC.…”

“…Skull‐base DCs are extremely rare and, to our knowledge, only 17 cases have been reported in the literature (Table 2). Pathognomonic features and aetiopathogenesis remain incompletely defined due to the lack of a large case–series.…”

“…Tumour histotype seems to be one of the most important prognostic factors . Sarcomatous, poorly differentiated and de‐differentiated variants are rare but extremely aggressive, and represent a challenge for the pathologist . Among these, de‐differentiated chordomas (DCs) are the most common.…”

“…They almost exclusively occur as recurrent disease or after radiation therapy, appearing as the final evolution of an aggressive chordoma, while de‐novo cases are exceptional. The vast majority of reported DCs arose from the sacral region and only a few from the skull base . Additionally, data on molecular and genetic alterations leading to tumour de‐differentiation are missing.…”

Immunophenotypic features of dedifferentiated skull base chordoma: An insight into the intratumoural heterogeneity

“…Skull base chordomas account for less than 0.2% of all intracranial neoplasms [ 5 , 10 , 21 ]. Recent studies suggest an incidence of chordoma of 0.08 cases per 100,000 with a peak incidence between 50-60 years of age, which is higher in men over women 1 : 0.6 [ 3 , 4 , 15 , 22 – 24 ].…”