A 69-year-old Chinese male presented via the emergency department with a one day history of mild shortness of breath. Upon closer interview, he also complained of a progressively enlarging left neck mass which had more than doubled in size over the period of six weeks. He did not note any stridor, hoarseness or dysphagia. The patient was a smoker of 50 pack years but did not consume alcohol. He had history of mild chronic obstructive pulmonary disease but otherwise did not have a family history of thyroid disorders. Physical examination showed a large (7 cm) left anterior neck mass which moved with swallowing. The mass was not tender and there was no retrosternal extension. There were no enlarged cervical lymph nodes or evidence of airway obstruction.
Blood tests performed showed a normal thyroid function with free thyroxine (fT4) at 12.85 pmol/L and thyroid-stimulating hormone at 0.619 microIU/L. The white blood cell count (WBC) was also elevated at 21.6 x 109/L. This was predominantly neutrophilic with an absolute neutrophil count of 17.9 x 109/L. However, the other inflammatory markers were not significantly raised with a C-Reactive Protein (CRP) of 62 mg/L and a Pro-Calcitonin of 0.13 microg/L.
Contrast-enhanced CT scan (Figure 1) showed a 6.4 x 5.6 x 4.9 cm solid-cystic nodule arising from the left thyroid lobe and encasing the left common carotid artery. The trachea was deviated to the right but there was otherwise no airway narrowing (Figure 2). There were also several subcentimeter necrotic lymph nodes within the left cervical region. In addition, the CT scan also revealed a 4.3 x 3.4 cm spiculated mass in the left upper lobe of the lung as well as several other smaller subcentimeter lung nodules (Figure 3). A contrasted CT abdomen and pelvis did not show any intra-abdominal pathology. These radiological findings raised the possibility of synchronous tumours.
The patient underwent a bedside fine needle aspiration (FNAC) of which copious amount of pus was aspirated and concurred on cytology. In view of this finding, the authors were swayed towards the possibility of tuberculosis.
An ultrasound-guided FNAC of the solid component of the nodule was arranged. This showed atypical squamous cells highly suspected for squamous cell carcinoma (Figure 4). No thyroid epithelial cells or anaplastic cells were seen in the cytology specimen. This finding contradicted the clinical impression of a common primary thyroid cancer. Acid fast bacilli (AFB) smears were negative.
The patient also underwent a CT guided biopsy of the lung lesion. Histology showed poorly differentiated carcinoma with squamous differentiation. Immunohistochemistry staining (Figure 5) showed diffuse reactivity to p40, CK7 and paired box 8 (PAX-8) and were negative for Napsin A and thyroid transcription factor-1 (TTF-1). This was suggestive of a thyroid primary rather than a primary lung squamous cell cancer.
In view of this, the patient was diagnosed as primary squamous cell carcinoma of the thyroid with nodal and lung metastases. As most patients with advanced disease succumb to airway obstruction, the patient was offered an elective tracheostomy. However, he declined all treatment and opted for best supportive care. The patient passed away six weeks later.