Poorly Differentiated Chordomas Showing Loss of INI1/SMARCB1: A Report of 2 Rare Cases With Diagnostic Implications

A Rare Case of Adult Poorly Differentiated Chordoma of the Skull Base With Rapid Progression and Systemic Metastasis: A Review of the Literature

Chordoma is a rare tumor that arises from chordal tissue during fetal life. Recently, the concept of poorly differentiated chordoma, a subtype of chordoma characterized by loss of SMARCB1/INI1 with a poorer prognosis than conventional chordomas, was established. It predominantly occurs in children and is rare in adults. Here, we report a rare adult case of poorly differentiated chordoma of the skull base with a unique course that rapidly systemically metastasized and had the shortest survival time of any adult chordoma reported to date. The patient was a 32-year-old male with a chief complaint of diplopia. MRI showed a widespread neoplastic lesion with the clivus as the main locus. Endoscopic extended transsphenoidal tumor resection was performed. Pathological findings showed that the tumor was malignant, and immunohistochemistry revealed a Ki-67 labeling index of 80%, diffusely positive brachyury, and loss of INI1 expression. The final diagnosis was poorly differentiated chordoma. Postoperatively, the residual tumor in the right cavernous sinus showed rapid growth. The patient was promptly treated with gamma knife three fractions. The residual tumor regressed, but the tumor developed systemic metastasis in a short period, and the patient died seven months after diagnosis. This report of a rapidly progressing and fatal adult poorly differentiated chordoma shows the highest Ki-67 labeling index reported to date. Prompt multidisciplinary treatment should be considered when the Ki-67 labeling index is high.

The NIH pediatric/young adult chordoma clinic and natural history study: Making advances in a very rare tumor

BACKGROUND

Chordomas are rare tumors arising from the skull base and spine, with approximately 20 pediatric chordoma cases in the Unitedn States per year. The natural history and optimal treatment of pediatric chordomas, especially poorly differentiated and dedifferentiated subtypes, is incompletely understood. Herein, we present findings from our first National Cancer Institute (NCI) chordoma clinic and a retrospective analysis of published cases of pediatric poorly differentiated chordomas (PDC) and dedifferentiated chordomas (DC).

METHODS

Patients less than 40 years old with chordoma were enrolled on the NCI Natural History and Biospecimens Acquisitions Study for Children and Adults with Rare Solid Tumors protocol (NCT03739827). Chordoma experts reviewed patient records, evaluated patients, and provided treatment recommendations. Patient-reported outcomes, biospecimens, and volumetric tumor analyses were collected. A literature review for pediatric PDC and DC was conducted.

RESULTS

Twelve patients (median age: 14 years) attended the clinic, including four patients with active disease and three patients with PDC responsive to systemic therapy. Consensus treatment, management, and recommendations were provided to patients. Literature review returned 45 pediatric cases of PDC or DC with variable treatments and outcomes.

CONCLUSIONS

A multidisciplinary expert clinic was feasible and successful in improving understanding of pediatric chordoma. While multimodal approaches have all been employed, treatment for PDC has been inconsistent and a recommended standardized treatment approach has not been defined. Centralized efforts, inclusive of specialized chordoma-focused clinics, natural history studies, and prospective analyses will help in the standardization of care for this challenging disease.

Poorly Differentiated Chordoma of the Clivus With Loss of SMARCB1 Expression in a Pediatric Patient: A Case Report

Poorly differentiated chordoma (PDC) is a rare, aggressive subtype of chordoma. A two-year-old girl presented with cervical pain, limb paralysis and respiratory failure. Magnetic resonance imaging and positron emission tomography-computed tomography revealed a tumor compressing the pons at the clivus and osteoblastic metastatic lesions of the left upper arm and right iliac bone. Her tumors shrank substantially after treatment with chemotherapy and proton beam therapy. Our initial diagnosis was an atypical teratoma/rhabdoid tumor, but final diagnosis of PDC was made on the basis of the immunohistochemical expression of brachyury. In addition, the detection of SMARCB1/INI1 mutation confirmed the diagnosis of PDC.

Notochordal Tumors

This review provides an overview of the spectrum of tumors showing notochordal differentiation. This spectrum encompasses benign entities that are mostly discovered incidentally on imaging, reported as benign notochordal cell tumor, usually not requiring surgical intervention; slowly growing and histologically low-grade tumors referred to as conventional chordoma but associated with a significant metastatic potential and mortality; and more aggressive disease represented by histologically higher-grade tumors including dedifferentiated chordoma, a high-grade biphasic tumor characterized by a conventional chordoma juxtaposed to a high-grade sarcoma, usually with a spindle or pleomorphic cell morphology, and associated with a poor prognosis and poorly differentiated chordoma.

Grossing and reporting of bone tumor specimens in surgical oncology: Rationale with current evidence and recent updates

Primary bone tumors, including sarcomas, are rare tumors and require a multidisciplinary approach, including inputs from a radiologist, pathologist, medical oncologist, and surgical and radiation oncologist, for optimal management. Over the years, there has been a paradigm shift toward the treatment of bone sarcomas, from radical resections to conservative surgical procedures, to achieve improved clinical and functional outcomes. This has led to receiving and processing various types of specimens in orthopedic oncopathology. Grossing and reporting of bone tumors require expertise. This review focuses upon the types of biopsies, grossing techniques of various specimens in orthopedic oncology and reporting, with rationale and recommendations from pathologists, actively involved in reporting and pursuing a special interest in bone tumors, based on current evidence. Furthermore, there is a section on some of the updates in the diagnosis of bone tumors, based on the recent fifth edition of the World Health Organization classification of tumors of soft tissues and bone.

Poorly differentiated chordoma showing loss of SMARCB1/INI1: Clinicopathological and radiological spectrum of nine cases, including uncommon features of a relatively under-recognized entity

Poorly differentiated chordoma is a newly recognized entity in the recent World Health Organization (WHO) classification of tumors of soft tissue and bone. Slightly over 60 such cases have been documented. Herein, we present a clinicopathological profile, including radiological features, of nine cases, which occurred in five males and four females, with age varying from 1 to 29 years (median = 43), in the cervical spine (n = 2), skull base (n = 2), clivus (n = 2), thoracic spine (n = 1) lumbar spine (n = 1) and coccyx (n = 1) Average tumor size was 4.8 cm. None of the 6-referral cases was diagnosed as a poorly differentiated chordoma at the referring laboratory. Histopathologically, all cases displayed a cellular tumor comprising polygonal cells (n = 9) displaying moderate to marked nuclear pleomorphism with prominent nucleoli (n = 7), eosinophilic (n = 9) to vacuolated cytoplasm (n = 7), rhabdoid morphology (n = 4), interspersed mitotic figures (n = 5), focal necrosis (n = 6) and inflammatory cells (n = 9). A single tumor displayed areas resembling classic chordoma, transitioning into poorly differentiated areas. There were multinucleate giant cells and physaliphorous cells in two tumors, each, respectively. Immunohistochemically, tumor cells were positive for AE1/AE3 (7/7), EMA (7/7), cytokeratin (CK) MNF116 (1/1), OSCAR (1/1), brachyury (9/9, diffusely), S100P (4/7, mostly focally), and glypican 3(2/4). SMARCB1/INI1 was completely lost in all nine tumors. A single case tested by FISH showed homozygous deletion of the SMARCB1 gene. Therapeutically (n = 7), all patients were treated with surgical resection (invariably incomplete) (n = 5), followed by adjuvant radiation therapy (n = 4) and chemotherapy (n = 4). While a single patient partially responded to treatment and another patient is alive with no evidence of disease after 23 years, three patients died of disease, six, eight, and 11 months post-diagnosis, despite adjuvant treatments. A single patient presented with a metastatic lung nodule, while another developed widespread metastasis. Poorly differentiated chordomas display a spectrum of features, are associated with a lower index of suspicion for a diagnosis, and display aggressive outcomes. Critical analysis of radiological and histopathological features, including necessary immunostains (brachyury and SMARCB1/INI1), is necessary for their timely diagnosis. These tumors show loss of SMARCB1/INI1 immunostaining and homozygous deletion of INI1/SMARCB1 gene.

Soft Tissue Special Issue: Chondroid Neoplasms of the Skull

Clinically, radiologically, and pathologically, chondroid neoplasms of the skull can be diagnostically challenging due to overlapping features in each of these domains. Compounding the problem for the pathologist, there is also significant morphologic, immunophenotypic, and molecular genetic overlap between benign and malignant cartilaginous lesions, and the majority of these lesions are encountered quite rarely in routine surgical pathology practice. Each of these factors contribute to the diagnostic difficulty posed by these lesions, highlighting the importance of radiologic-pathologic correlation in the diagnosis. This review is intended to provide an update for surgical pathologists on some of the most commonly encountered chondroid neoplasms in the skull, and includes the following lesions: chondromyxoid fibroma, synovial chondromatosis, chondrosarcoma and variants, and chordoma and variants. For each of these lesions, the differential diagnosis and useful ancillary tests will be discussed in the context of a broad range of additional primary and secondary lesions.

Clinicocytopathological spectrum, including uncommon forms, of nine cases of chordomas with immunohistochemical results, including brachyury immunostaining: A single institutional experience

OBJECTIVES

To present clinical and cytopathological features of nine cases of chordomas, diagnosed over 9 years and confirmed by brachyury (T) immunostaining.

METHODS

Conventional cytological smears, stained with Papanicolaou and May-Grünwald Giemsa, along with corresponding histopathological (n = 8) and immunostained sections (n = 8) were reviewed. Immunohistochemical staining was performed on tissue sections by polymer detection technique.

RESULTS

Nine tumours occurred in seven males and two females, with age ranging from 36 to 72 years (average = 58.7), in the sacrum (seven) and spine (two). On fine needle aspiration cytology, five cases were either diagnosed with or diagnosed with a suggestion of a chordoma, while three cases were diagnosed with chordoma as a differential diagnosis. On review, smears were moderately cellular, comprising myxoid stroma (9/9), epithelioid cells (9/9), physaliphorous cells (8/9), including binucleation (7/9), prominent nucleolisation (2/9), pleomorphic cells (2/9) and intranuclear inclusions (3/9). Immunohistochemically, tumour cells expressed cytokeratin (4/4), pan cytokeratin (4/4), epithelial membrane antigen (8/8), S100 protein (6/8) and brachyury (8/8). Five patients underwent surgical excision, including two who underwent adjuvant radiotherapy (RT) and four patients who underwent RT. During follow-up (n = 8), a single patient developed recurrence and another presented with metastatic lesions. Finally, five patients were alive with disease (7-53 months); a single patient was free of disease (4 months), and two patients died of disease; the latter cases displayed pleomorphic cells and intranuclear inclusions.

CONCLUSIONS

Chordomas can be primarily diagnosed by fine needle aspiration cytology in a typical clinicoradiological setting with a combination of key cytomorphological features. Pleomorphic cells and intranuclear inclusions are associated with a relatively aggressive subtype. An exact diagnosis has treatment implications and requires confirmation by brachyury immunostaining.