A 58-year-old man presented to us three years ago with a history of progressive anterior neck swelling and hoarseness of voice for the past one month. On clinical examination, there was palpable left anterior neck swelling with cervical lymphadenopathy. A core needle biopsy of the lesion revealed invasive poorly differentiated carcinoma. He defaulted our follow-up and opted for a left hemithyroidectomy at another institution. The histopathological report was intrathyroid thymic carcinoma. He refused adjuvant radiotherapy despite being counselled and subsequently defaulted follow-up.\nRecently, the patient presented to us again with progressive hoarseness of voice and intermittent haemoptysis. He had shortness of breath, especially when lying flat, but no difficulty in swallowing. On clinical examination, there was a left supraclavicular mass measuring 2 × 2 cm. The mass was immobile and hard in consistency. The anterior aspect of the neck showed an irregular hard mass measuring 3 × 4 cm. An indirect laryngoscopy examination revealed a left vocal cord palsy, likely from his previous presentation. An intraluminal mass was seen over the posterior tracheal wall, occupying a third of the tracheal lumen. We proceeded with a contrasted computed tomography (CECT) of the neck and thorax, which revealed a lobulated hypodense soft tissue mass measuring 4.3 × 3.9 × 5.2 cm. It occupied the left thyroid bed from the C7/T1 to the T2/T3 vertebral level, with left retrosternal extension and tracheal deviation to the right. The soft tissue mass had displaced the left common carotid artery and internal jugular vein laterally. As the CECT showed (, ), the soft tissue mass had caused more than 80% of tracheal luminal narrowing. At retrosternal, multiple matted lymph nodes were seen.\nImage-guided fine needle aspiration cytology (FNAC) of the soft tissue mass at the left thyroid bed showed malignant cells suggestive of intrathyroid thymic carcinoma (CASTLE). After a multidisciplinary meeting, we planned for curative resection and tracheostomy. Intraoperative tracheoscopic examination showed a soft tissue mass measuring 3 cm in length at the posterior tracheal wall, 2.1 cm from the vocal cord (). The mass was debrided to achieve an adequate diameter of tracheal lumen distal to the tracheostomy insertion. The left supraclavicular solid tumour densely adhered to the left great vessels. Due to a high risk of injury to the great vessels, we proceeded with tumour debulking only.\nThe histopathology report showed an unencapsulated tumour that displayed lobular architecture. The tumour lobules were composed of sheets of neoplastic polygonal cells rimmed by a variable amount of mature lymphocytes. The neoplastic cells were mildly pleomorphic, and lymphovascular invasion was present. Skeletal muscle bundles attached at the periphery showed focal tumour cell infiltration (, ). Immunohistochemical studies were immunoreactive for CD5 (membranous pattern) and CD117 but negative for thyroglobulin and TTF1 (, ). The proliferative index, Ki67, was approximately 20%.\nPostoperative care was unremarkable, and no immediate complications were noted. The patient was counselled for adjuvant chemoradiotherapy, but he was not amenable to this course of action. He is currently under regular follow-up with no disease progression six months after the operation.
A 60-year-old woman, who was diagnosed with cancer of the thyroid gland in 2015, was treated with total thyroidectomy and lymph node dissection. Her postoperative pathology showed carcinoma showing thymus-like differentiation (CASTLE). She was discharged on Levothyroxine 100 mg/day. She did not attend her follow-up appointments. After 2 years, the patient found a lump in the left side of her neck. The tumor grew very slowly and did not cause any symptoms; hence, she did not seek medical advice. In May 2020, about 3 years after the appearance of her left neck tumor, the patient was admitted to our hospital with shortness of breath due to tracheal compression from the tumor. Clinical examination showed enlarged solid painless cervical lymph nodes at levels III and IV, stuck in a block size of 3 × 6 cm in diameter. There was no involvement of the hypopharynx, and her vocal cords were intact. CT scan of her neck revealed a 16 × 54 mm lesion compressing the trachea, and several enlarged left cervical lymph nodes with the size of about 25 mm (Fig. ). The patient was offered a tracheostomy and tracheal stent before undertaking further investigations.\nHer subsequent fluorine-18-labeled fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scan revealed previous total thyroidectomy, no evidence of recurrence in the surgical bed, enlarged left cervical lymph nodes at levels III and IV, and extranodal extension into sternocleidomastoid muscle measuring 29 × 43x59 mm, with the maximum standardized uptake value (SUV max) of 6.8. Her thymus measured 19 × 31x37mm, with increased metabolism of FDG (SUV max 3.6). There was a 33 × 39x49 mm mass on the left side of the anterior mediastinum, showing an undefined margin with neighboring organs in the trachea and the thorax (SUV max 6.0). It also showed multiple lymph nodes near the lower trachea, next to the superior vena cava, posterior thymus, and aortic loop; the largest node was 26 × 40 mm, with increased metabolism of FDG (SUV max 7.9). The other organs were unaffected. There was no metastasis in other organs (Fig. ).\nThyroid function tests showed TSH: 0.00726 mIU/L[0,4-5], FT4: 22.34 pmol/L [12-22] and FT3: 4.0 pmol/L [1, 3-3, 1]. We reviewed the pathology of the current cervical lymph node specimen and that of the thyroid specimen from 5 years ago (2015). This showed that the thyroid tumor consisted of invasive cells which were poorly differentiated with squamous cell morphology, different from conventional thyroid carcinoma. The immunohistochemistry (IHC) analysis showed positive staining with CK5, CK7, p63, C-kit, CD5 and negative with TTF-1, Thyroglobulin, GATA3, ER, CD99, and NKX2.2, confirming CASTLE pathology in both the specimens.\nThe patient was diagnosed with a recurrence of the CASTLE thyroid gland in cervical lymph nodes. She was assessed by thoracic, and head and neck surgeons for the possibility of removing the maximum of recurrent tumors. However, it was considered a difficult, high-risk procedure; she and her family declined to go ahead with the surgery. Then, we offered the patient treatment with palliative radiotherapy. However, she and her family declined the treatment and got the patient discharged from the hospital. She was followed up without intervention and is currently stable 15 months after the recurrence.