PMC5836208_01
Computed tomography (CT) scans with contrast enhancement (a-c) showed lymph node swelling of the neck, mediastinum, and left axilla. 18F-fluorodeoxyglucose positron emission tomography/CT (d) showed a hot spot in the right lobe of the thyroid.
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F1
A computed tomography (CT) scan with contrast enhancement showed enlarged lymph nodes in the neck, mediastinum, and left axilla (Fig. 1a-c). A right supra-clavicular lymph node biopsy revealed poorly differentiated carcinoma. 18F-fluorodeoxyglucose positron emission tomography/CT showed hot spots in the right lobe of the thyroid and lymph nodes (Fig. 1d).
Hematoxylin and eosin staining showed numerous foci of atypical cells between follicles in the thyroid tissue. The tumor cells in a and b showed sheet-like arrangement, but no keratinization, intercellular bridge, glandular structure or mucin production. Because of such undifferentiated features, the tumor was diagnosed as undifferentiated thyroid cancer at first. Further study revealed that all tumor cells were within the D2-40-positive lymph ducts, did not infiltrate thyroid parenchyma (c), and were positive for p40 (d). These results showed that the tumor is metastatic squamous cell carcinoma of unknown primary.
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F2
Microscopically, undifferentiated carcinoma was suspected (Fig. 2).
A chest CT scan showed mosaic patterns with ground-glass opacities in both lungs (left). A chest X-ray taken on day 35. Diffuse infiltrative shadows were observed in both lung fields (right).
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F3
A CT scan after 1 month of lenvatinib administration showed marked regression of the lymph nodes in the mediastinum and left axilla; however, interstitial pneumonia was also detected in the bilateral lung (Fig. 3). Chest auscultation of both lung fields revealed no crackles, wheezes, or rhonchi, and chest X-ray showed bilateral infiltrative shadows (Fig. 3).
Clinical course of the patient. Day 1 is the starting date of the first cycle of lenvatinib administration. CBDCA, carboplatin; PTX, paclitaxel.
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F4
Following three cycles of chemotherapy with carboplatin and paclitaxel, stable disease was achieved in accordance with RECIST criteria (Fig. 4).