A Rare Chordoma-The Epiglottic chordoma

Abstract

Chordomas are rare malignant bone tumors. Chordomas originate from notochordal elements. Chordomas have the phenotype of the embryonic notochord, characterized by the dual expression of cytokeratin and brachyury. Chordomas occur anywhere along the central axis. Rarely, chordomas occur in extra-axial structures. We could not find any reports on epiglottic chordoma. Here, we present a case of epiglottic chordoma to highlight this rare cause of laryngeal mass.

Introduction

Chordomas are a rare malignant bone tumors with an annual incidence of 0.1 every 100 000 individuals, of which 30% occur at the skull base. ¹ Chordomas originate from notochordal elements.^2–5 Chordomas occur anywhere along the central axis but may also structures outside the central axis, such as skeletal muscle. ⁶ Computed tomography and magnetic resonance imaging are required to determine tumor localization and extent of tumor growth.

Case report

A 62-year-old female was admitted to the head and neck department of Shandong Second Provincial General Hospital for swallowing foreign body sensation in two months in April 2019 foreign body sensation with swallowing for the prior two month. Previously, the patient had no dysphagia, throat pain, cough, fever, or dyspnea.

Examination

Laryngoscopy performed in the outpatient department showed smooth cystic hyperplasia on the epiglottic laryngeal surface. The patient underwent plain and enhanced CT, which revealed an analogous round mass on the epiglottic laryngeal surface. The mass was well-defined with slight hyperdensity on the CT images. The mass showed no enhancement in the arterial phase and slight enhancement in the venous phase after injection of the contrast agent. (Figure 1)

Figure 1.

A 62-year-old woman presented with a 2-month history of swallowing obstruction. Plain CT scan and 3D reconstruction CT revealed an analogous round and slightly low-density mass on the epiglottic laryngeal surface (A, D, E). The mass showed no enhancement in arterial phase (B) and slightly nodular and enhancement in venous phase (C, F) after injection of contrast agent on enhanced CT image.

Treatment and histopathology

The patient underwent endoscopy with CO₂ laser excision. The tumor was completely resected and the margins were negative. Combined with histopathological and immunohistochemical features, the patient was treated by adjuvant radiotherapy after surgery. The patient recovered well and was discharged on medical advice. Thirty-six months follow-up showed that the patient was recovering well, and so far there is no recurrence.

Based on histopathology (Figure 2) and immunohistochemical staining (Table 1), the patient was diagnosed with epiglottic chordoma.

Figure 2.

Tumor cells are typically arranged in cords (hematoxylin and eosin, ×10).

Table 1.

Results of Immunohistochemical Staining.

Name	Result	Definition
CK	+	Cytokeratin, Cytokeratins (CK) are a group of antigenically structural filaments specific to epithelium that are preserved in metastasis and malignant transformations
CK7	−	Cytokeratin 7 (CK7) is specifically expressed in the simple epithelia lining the cavities of internal organs and in transitional epithelium. CK7 is a specific marker for salivary gland tumors
CD117	−	CD117 also known as proto-oncogene c-Kit or tyrosine-protein kinase Kit, is a protein that in humans is encoded by the KIT gene. CD117 is a specific marker for gastrointestinal stromal tumors
SOX-10	+	SOX-10 is a transcription factor essential for Schwann cell development. SOX-10 represents a marker for schwannian differentiation
S-100	+	S-100, so called for its solubility in a 100% saturated solution of ammonium sulfate, was described as an acidic protein unique to the nervous system
GFAP	+	Glial Fibrillary Acidic Protein (GFAP) is a cytoskeletal protein, the main filament in mature astrocytes in the central nervous system (CNS). GFAP is produced only by astrocytes, so this protein is a specific marker for brain glial cell
P63	−	P63 is a transcription factor. Alteration of p63 expression is linked to tumorigenesis. In 80% of HNSCC (head and neck squamous cell carcinoma) data show an amplification of p63 gene
P40	−	The p40 antibody is a highly specific marker for the squamous cell carcinoma subtype of non-small cell lung carcinomas (NSCLC)
SMA	−	Myofibroblasts are usually demonstrated by the presence of alpha smooth muscle actin (SMA) expression
Ki-67	3%	Ki-67 is a non-histone nuclear and nucleolar protein cell proliferation encoded by MKI-67 gene.Ki-67 is a cell proliferation marker

This case was misdiagnosed as an epiglottic cyst before surgery and as a lesion of small salivary gland by rapid intraoperative pathology.

Discussion

Chordomas are rare, accounting for approximately 1–4% of all bone malignancies. ¹ Chordomas originate from embryonic remnants of the primitive notochord.^2-5 In the third week, the notochord was attached cephalally to the oropharyngeal membrane. As the notochord degrades, it may remain or dislocate adjacent structures around it, and the remaining notochord tissue can develop chordoma.^2,3 Chordomas can occur anywhere along the mid axis. Rarely, chordomas can occur in extraxial structures such as skeletal muscle.^5,7 Chordomas in the larynx are rare. We believe that the epiglottic chordoma was caused by residual or dislocated notochord in the epiglottis. This may be caused by the cephalic proximity of the notochord to the oropharyngeal.

Chordomas should be differentiated from chondrosarcomas and myoepithelial neoplasms. Microscopically, chordomas appeared as lobulated structures with fiber bundles composed of densely packed spindle-shaped fibroblast-like cells encased in a population of highly vacuolated (eosinophilic) epithelioid tumor cells. Eosinophilic cells are loosely arranged and embedded in a unique and complex extracellular matrix. In some chordomas, the characteristic myxoid matrix may have hyaline cartilaginous features similar to hyaline chondrosarcoma. However, conventional hyaline chondrosarcoma may have “vacuoles” within the stroma, which at low power may mimic physaliferous cells; however, the tumor cells reside within lacunae, rather than having corded appearance. The myoepitheliomas , with their corded neoplastic cells set in a chondromyxoid stroma, can be confused with chordomas however physaliferous are not present. Since chondrosarcoma and chordoma have similar imaging features, neither MRI nor CT can be used to distinguish chordoma from chondrosarcoma preoperatively. The essential diagnostic immunoprofile of chordoma is the co-expression of cytokeratins(CK) and brachyury.^8-12 Based on histopathology and immunohistochemical staining, the differential diagnosis of chordoma, chondrosarcoma, and myoepithelial neoplasms can be made.

Surgical procedures play the key role in the treatment of chordoma. When total en-bloc resection or gross total resection is not feasible, radical or near total intralesional resection is recommended. The patients were then treated by radiotherapy after surgery. ¹

Chordoma was mainly confirmed by combining histopathology and immunohistochemical staining. In particular, the diagnosis of chordoma in rare areas such as the epiglottisdepends on histopathology and immunohistochemistry. Preoperative diagnosis of chordoma is very difficult. This case was misdiagnosed as an epiglottic cyst before surgery and as a lesion of small salivary gland by rapid intraoperative pathology. Based on the no expression of CK7, salivary gland tumors were excluded. Based on histopathology and immunohistochemical staining, this patient was diagnosed with epiglottic chordoma. The patient was then treated by adjuvant radiotherapy after surgery.