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The group of notochordal tumors consists of the benign notochordal cell tumor and the conventional, dedifferentiated and poorly differentiated chordomas in the fifth edition of the WHO classification of bone and soft tissue tumors. This update covers recent advances in the knowledge of the histogenesis and biology of these tumors and their implications in terms of diagnosis, prognosis assessment and therapeutic management., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Introduction: Chordomas are rare malignant midline tumors, presumed to arise from notochordal remnants. This was further suggested by the discovery of the brachyury in chordomas pathogenesis. Its immunohistochemical expression has become the principal adjunct in the diagnosis of chordomas. However, studies about brachyury expression in chordomas are not fully comparable, mainly because they use different primary antibodies. Thus, the aim of this study is to investigate the expression of brachyury expression in a series of chordomas in conjunction to clinicopathological characteristics and to review the relevant literature providing all the details needed in the immunohistochemical study of brachyury., Materials and Methods: This is a retrospective study of 62 chordomas, diagnosed over a 22-year period. No dedifferentiated or poorly differentiated cases were included. A monoclonal primary antibody (clone A-4) was used and brachyury expression was evaluated by the H-score. Clinicopathological parameters studied were age, sex, tumor localization, decalcification status and tissue age. Fetal notochords were used for comparison., Results: Mean H-score of nuclear brachyury expression was 129.8. The tissue age significantly influenced brachyury expression, the older samples expressing less brachyury. Decalcification demonstrated a trend to weaken brachyury expression. Clinical characteristics were not correlated with the patterns of brachyury expression. Notochords were negative. Literature review reveals several polyclonal antibodies used and a positivity of 75%-100% in chordomas with even more variable results in notochords., Conclusion: In chordomas, as in other tumor types, an uniformization of studies about brachyury expression is needed, by considering the clone used, and the decalcification and the age of the sample, given the growing importance of brachyury in diagnosis and therapeutic steps., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Aims: To study the clinicopathological and molecular features of benign notochordal cell tumours (BNCTs) and their differential diagnosis from chordoma., Methods: 13 cases of BNCT were investigated. The genome-wide copy number imbalances were performed using Oncoscan CNV array in three cases and fluorescence in situ hybridisation (FISH) detection of epidermal growth factor receptor (EGFR)/chromosome 7 enumeration probe (CEP7), LSI1p36/1q21, LSI19p13/19q13, CEP3/CEP12 and Telvysion 6 P was performed in 13 cases., Results: All 13 BNCTs were symptomatic and eight cases showed a close relationship with the bones of the skull base. The important histological character for differential diagnosis with chordoma was the absence of extracellular matrix and eosinophil cells and the presence of vacuoles in most tumour cells. Immunohistochemical staining of AE1/AE3, vimentin, epithelial membrane antigen, S-100 and brachyury (100% each) were positive in BNCTs. Gain of chromosome 7 occurred in 10 cases (76.9%), gain of 1p in four (30.8%), gain of 1q in five (38.5%), gain of 19p and 19q in five (38.5%), gain of chromosome 12 in 11 cases (84.6%), gain of 6p in eight (61.5%) and gain of chromosome 3 in four cases (30.8%)., Conclusions: In contrast to chordoma, chromosome gain or normal copy number was more common while chromosome loss was infrequent in BNCTs. This may be a differential diagnosis clue for chordoma and may be an important characteristic in the progression of notochordal cell tumours., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

By the current WHO classification, benign notochordal cell tumor (BNCT) and chordoma comprise the entire spectrum of notochordal-derived tumors. They have defined radiologic and histologic criteria, and differ considerably in management and clinical outcome. Chordomas are malignant tumors; they show progressive, destructive growth and have the capacity for metastasis. In contrast, BNCT are benign and show limited intraosseous growth. Patients with BNCT can be managed with serial imaging or conservative excision, whereas patients with spinal/sacral chordomas typically undergo radical en bloc resection often with adjuvant therapy and significant morbidity. As such, the distinction between BNCT and chordoma is critically important. We have seen 4 unusual notochordal tumors with radiologic and/or histologic features that defy classification as either BNCT or chordoma. Cases occurred in 4 adults (53 to 83 y), and involved the lumbar spine (N=2) and sacrum (N=2). Three cases had subtle radiologic features of cortical permeation with minimal soft tissue extension. All 4 cases had the characteristic histologic features of BNCT; however, 2 cases also had focal myxoid change. Three patients were followed with serial imaging (follow-up range, 26 to 120 mo); 2 showed no disease progression and 1 had a 10-year cumulative interval growth of 3.7 mm. One patient underwent sacrectomy. The tumor was examined in toto and had the characteristic histologic features of BNCT, with the exception of minimal soft tissue extension. On the basis of these observations, we propose a provisional designation of atypical notochordal cell tumors (ANCT) be used for the subset of notochordal-derived tumors that fail to fulfill current diagnostic criteria for either BNCT or chordoma. We would argue that designating these atypical notochordal tumors as chordoma precipitates potentially overly aggressive surgical management. Patients with ANCT may be better managed by close observation and serial imaging. Additional studies with more cases and longer clinical follow-up should clarify the relationship of ANCT to BNCT and chordoma.

Purpose: To analyze the clinical data, MRI, pathological diagnosis, treatment and long-term effects of benign notochordal cell tumor (BNCT), a newly described novel spine tumor., Methods: We retrospectively studied 11 patients' clinical data of the above., Results: The ratio of males to females was 4:7, and the average age was 49.2 years (range, 18-74 years). Cervical vertebra (5; 38.5%) and thoracic vertebra (5; 38.5%) were the most frequent site followed by the lumbar vertebra (3; 23%). Pain was the main symptom except case 2 who were diagnosed accidently because of prostate cancer. The mean delay from first clinical symptoms to diagnosis was ranged from 2 months to 20 years. MRI showed all BNCTs were osteolytic lesions with hypointense on T1-weighted sequences, hyperintense on T2-weighted sequences. There were 4 vertebral bodies with wedge fracture. There were two cases that had two noncontiguous vertebral bodies with BNCT. In histology, marrow replacement was noted by multivacuolated physaliphorous cells immunoreactive for CK, EMA and S100 protein. All 10 cases except case 2 had vertebral reconstruction and fixation with different methods. Of the 11 patients, 9 had full follow-up data which showed no evidence of recurrence or metastasis without further treatment., Conclusion: Noncontiguous multi-centricity BNCTs are rare. No specific vertebrae are more frequently involved. Once BNCT is diagnosed by pathology, the surgical intervention is necessary for the patients with obvious clinical symptoms although it is benign. There is no evidence of BNCT recurrence or metastasis.

We report two cases of histologically proven benign notochordal cell tumour (BNCT) with imaging evidence of entrapped intralesional marrow and discuss the relevance of previously undescribed imaging feature.

This article presents a case of a 53-year-old woman who presented with intermittent, dull, poorly localized lower back and buttock pain. The pain worsened in a seated position or after long periods of standing. A T1-weighted magnetic resonance image (MRI) of the sacrum and coccyx revealed a well-demarcated intraosseous lesion with homogeneous low signal intensity, while T2-weighted MRIs demonstrated homogeneous high signal intensity. An excisional biopsy revealed benign notochord cell tumor. The biopsy proved to be effective, as it relieved the patient's coccydynia. Due to the rarity of intraosseous benign notochordal cell tumors, it is essential to document and review this type of tumor. Only 2 benign notochordal cell tumors involving the coccyx have been previously reported, both of which presented with the same clinical symptoms of chronic coccydynia as our patient, likely due to the location of the involved lesion. The other leading diagnosis in our patient was chordoma, a malignant and locally aggressive neoplasm that is important to consider and exclude. Although chordomas have been well characterized in the surgery, pathology, and radiology literature, the benign notochordal cell tumor is a relative newcomer.

Study Design: Case report., Objective: To present a rare case of a notochordal cell tumor., Summary of Background Data: We report on a 27-year-old female patient with pain at the lower back and muscle cramps in the area of the right hip. Image studies demonstrated a cystic lesion of the coccyx., Methods: As clinical symptoms became chronic and were resistant to conservative treatment, a resection of the coccyx was performed., Results: Histology revealed an intraosseous benign notochordal cell tumor. This tumor represents a recently described notochordal cell proliferation biologically distinct from chordomas., Conclusions: Overdiagnosis of these notochordal cell proliferations as chordomas may occur if clinicians and pathologists are unfamiliar with the spectrum of notochordal proliferations.