Description

A 74-year-old man with a previous medical history of hypertension, type 2 diabetes mellitus and gastro-oesophageal reflux presented with acute hypoxic respiratory failure. The patient was aware of a mass on his sternum for ~18 years prior to presentation and was told by his previous healthcare provider that it was a benign enchondroma. He remained asymptomatic for most of the duration of the mass until a few months prior to seeing another medical provider after experiencing increasing pain and size of the mass. A computed tomography (CT)-guided core biopsy was done and revealed a well-differentiated chondrosarcoma (figure 1). Shortly after biopsy, the patient noticed increased weight loss and rapid growth of the mass. Concerned for rapid tumour progression, a repeat positron emission tomography (PET)-CT scan showed extensive retrosternal, lung, phrenic nerve and pericardial involvement causing mass effect on the heart that was deemed inoperable by a thoracic oncology surgeon (figure 2). He underwent two rounds of treatment with pembrolizumab. Biopsies were done of the sternum and lung nodule at this time because of concern of dedifferentiation. These biopsies again showed well-differentiated chondrosarcoma. Having made no progress with pembrolizumab, he was started on liposomal doxorubicin. A month after receiving his first round of liposomal doxorubicin, he presented to the emergency department with increased difficulty in breathing requiring 4 L of oxygen and lower extremity oedema. An echocardiogram was obtained which showed a left ventricular ejection fraction of 65%. A CT angiogram was also done to rule out an acute pulmonary embolism (PE) and although no PE was found, there was compressive atelectasis of the left lung. Pulmonology was consulted and recommended against endobronchial stent placement in light of significant tumour burden. A few days after being admitted the patient’s oxygen requirement increased requiring 60% oxygen via high flow nasal cannula. Despite these efforts, the patient ultimately went into cardiopulmonary arrest and died.

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Figure 1

Histology of the chondrosarcoma biopsied from chest wall.

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Figure 2

CT of the chest showing chondrosarcoma of the chest wall with extensive mediastinal involvement.

Primary malignant tumours of the chest wall make up approximately <1% of all primary tumours.1 They are among the rarest cartilage tumours with chondrosarcomas encompassing 15% of the cases.2 Our patient was initially diagnosed with an enchondroma presumably due to the rarity of chondrosarcomas of the chest. No records of any biopsies were available as the diagnosing physician resided in another country. Both can present with a slow-growing mass that can be non-tender and later become painful due to lytic bony destruction.3 Our patient’s mass resulted in a malignant tumour that may have otherwise been treated with surgical resection. Nevertheless, even if the lesion were an enchondroma, these tumours can malignantly degenerate into chondrosarcomas—necessitating close follow-up.3 In one study, the single most important factor that predicted a favourable outcome was the ability to perform a complete resection of the tumour with survival reaching 80% at 5 years.4 Unfortunately, our patient had widespread disease which was not amenable to complete surgical resection. Instead, he received the programmed death-ligand 1 (PDL-1) inhibitor—pembrolizumab—which one phase II trial recently reported a partial response rate of only 25% in five patients with chondrosarcoma.5