Chondrosarcoma of the thyroid cartilage: surgical management of a rare case

Abstract

Laryngeal malignancy encompasses about 1% of all cancers. Chondrosarcoma in the head and neck region represents about 0.1% of head and neck malignancies. Typical presenting symptoms relate to the anatomical location of these tumours and include dysphonia, inspiratory stridor, dysphagia, odynophagia or a neck mass. Benign and malignant cartilaginous cancers of the larynx have been described, and preoperative diagnosis can be difficult. Our report highlights the surgical management of a male patient in his 50s with chondrosarcoma of the thyroid cartilage.

Background

Cartilaginous tumours of the head and neck present infrequently but are a diagnostic challenge. Laryngeal chondrosarcomas typically present with symptoms based on the location of the tumour. We discuss the presentation, investigations and management of a difficult case with a patient presenting with chondrosarcoma of the thyroid cartilage.

Case presentation

A male patient in his 50s presented to the outpatient clinic with an 8-month history of progressive hoarseness. He denied dysphagia, dyspnoea, weight loss or otalgia. Flexible rhinolaryngoscopy showed fullness of his right vocal cord, while remainder of his head and neck examination was unremarkable.

The patient was brought to theatre for microlaryngoscopy; however, no specific pathology was observed, and the impression was of extrinsic compression of the cord.

Imaging (CT and MRI) demonstrated an irregular calcified lesion of the right thyroid cartilage, measuring 1.1×1.3×1.4 cm, protruding medially against the vocal cords (figure 1A, B). MRI showed evidence of invasion of overlying strap muscles (figure 1C), without associated cervical lymphadenopathy. Positron emission tomography (PET) CT reported normal fluorodeoxyglucose (FDG) uptake. CT-guided fine needle aspiration (FNA) was attempted although proved unsuccessful due to the hard impenetrable nature of the mass.

Figure 1.

CT and MRI. Axial CT (A) and MRI (B) demonstrating a calcified mass arising from the right thyroid cartilage lamina protruding medially against the vocal cords (MRI T1, postgadolinium enhancement).

The case was discussed at the local head and neck oncology multidisciplinary team meeting (MDM), and an open biopsy was recommended for definitive tissue diagnosis. A 4 mm punch biopsy was subsequently performed through a minimally invasive 2 cm midline neck incision. Histological analysis of the biopsy demonstrated a cartilaginous lesion with increased cellularity and mild atypia, without high-grade features, in keeping with a low-grade cartilaginous lesion, most likely a benign chondroma.

Following findings from histopathology, the case was rediscussed at the head and neck oncology MDM, and due to low-grade histological features, conservative surgical excision was advised. The patient elected to proceed with surgical management. At the time of operation, a 2.0 cm hard spherical mass was identified invading through the right thyroid cartilage lamina (figure 2). A 5 mm margin was taken around the spherical mass. Operating microscope and HMM diamond burr cutting drill were used. Once a plane was identified, careful dissection was used to separate the mass from the underlying muscle, taking care not to breach the inner mucosa and to preserve the vocal cords. The tumour was excised en bloc, and the wound was closed primarily. The patient had an uneventful postoperative course. Final histology demonstrated a cartilaginous lesion with minimally increased cellularity, nodular growth and occasional binucleate nuclei (figure 3). This confirmed the diagnosis of a low-grade (grade 1) chondrosarcoma which was completely excised with clear margins. At 6 months postoperatively, the patient is clinically and radiologically disease free with good postoperative voice.

Figure 2.

Resected ovoid-oriented lesion of the lamina of the right thyroid cartilage, measuring 2.5×2 cm. The lesion grew both medially and laterally from the thyroid lamina.

Figure 3.

Histopathological images 10× (A) and 20× magnification (B) showing cartilage with moderate increase in cellularity and mild atypia.

Discussion

Chondrosarcomas of the larynx are rare locally aggressive malignancies characterised by the formation of cartilaginous matrix and accounting for <1% of laryngeal neoplasms.¹ Their aetiology is unknown, but most patients are men (5:1) between their sixth and seventh decades of life. Chondrosarcomas are typically located at the metaphyseal ends of long bones, in the femur and humerus, and classified into grades 1, 2 or 3, based on the criteria by Lichtenstein and Jaffe.² When found in the larynx, they are usually a slow-growing tumour, most commonly originating from the cricoid cartilage (70%) with less than 20% found in the thyroid cartilage.³

The interest of this case lies in the diagnostic uncertainty differentiating between a benign chondroma and a low-grade chondrosarcoma. Our case highlights this difficulty as MRI reported a concern of a chondrosarcoma due to the involvement of the overlying strap muscles, which conflicted with the initial benign biopsy report. One review article, discussing the imaging features of cartilaginous tumours of the head, describes the limited utility of CT, MRI and PET CT in differentiating between low-grade chondrosarcoma and chondroma, as both exhibit similar features (including calcification and low-FDG uptake). The authors mention that invasion of adjacent structures on MRI favours a malignant rather than a benign diagnosis but conclude that histopathology is always required for confirmation.⁴ Notably, however, low-grade chondrosarcomas are also histologically difficult to differentiate from chondromas due to their similar appearance.⁵ Most studies cite that presence of binucleated chondrocytes are required for a diagnosis of low-grade chondrosarcoma; however, this is not always present, and both show low-grade features and low-mitotic activity. In addition, and relevant to our case, histopathological evidence demonstrates the majority of laryngeal chondrosarcomas (almost 60%) have an associated chondroma, which further complicates preoperative diagnosis.⁵ At present, molecular techniques to assist in distinguishing chondromas and chondrosarcomas are being developed, but they have not yielded any clinically significant contribution.⁶

In addition to the above diagnostic uncertainty, the rarity of this cancer makes it difficult to determine treatment, prognosis and follow-up. The consensus is that surgery is the treatment of choice for both benign and malignant lesions.^{7 8} Conservative excision is the usual management for chondromas, and radical excision is for chondrosarcomas due to the higher risk of metastasis. Laryngectomies have been performed in cases of large lesions presenting with obvious malignant features or airway compromise.⁹ Radiotherapy and chemotherapy play limited roles in primary treatment.^{10 11} Chondrosarcomas are chemoresistant because of their poor vascularisation and slow-growing nature, with radiotherapy only considered for unresectable lesions or as adjuvant therapy for positive margins.¹⁰ The reported limited use of both chemotherapy and radiotherapy in the literature reflects the current guidelines and typically are reserved for dedifferentiated chondrosarcoma, systemic metastasis or in cases of unresectable recurrence.^11–13 One study based on a national database of 5000 cases of chondrosarcoma, including non-head/neck sites, found there were not enough patients who received radiation only, or radiation plus chemotherapy, to determine their benefit or perform survival analysis.¹²

The most important prognostic indicator for chondrosarcomas is tumour grade. One review compared the management and outcomes of thyroid chondrosarcomas and identified only 17 low-grade lesions published in the literature to date.⁸ Of these, 11 were treated with partial laryngectomy, 5 with total laryngectomy and 1 patient initially treated with partial laryngectomy later received a total laryngectomy. After an average time of 10 years of follow-up, 76% had no evidence of recurrence; however, there are some conflicting reports with recurrence reported between 18% and 40%.^{2 3 9}

The evidence base for management of laryngeal chondrosarcomas is sparse with case reports or series dictating management. Our case demonstrates a laryngeal chondrosarcoma treated with local excision avoiding complete or partial laryngectomy and avoiding postoperative radiotherapy.

Learning points.

• Laryngeal cartilaginous cancers are rare and typically present in the cricoid cartilage.

• Low-grade chondrosarcomas and chondromas of the larynx have been described; however, they are difficult to differentiate with imaging and histologically.

• The principal treatment of both benign and malignant disease is surgical excision.

Ethics statements

Patient consent for publication

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