PMC5875061_01
Chest X-ray showing an apparent nodule in the left upper lung field (a). Contrast-enhanced computed tomography of the chest, showing a large nodule with surrounding ground-glass opacity in the left upper lobe of the lung (b).
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Her chest X-ray suggested a nodule in the left upper lung field (Figure 1(a)), and a contrast-enhanced computed tomography (CT) scan revealed a large nodule (41 x 33 mm in size) with surrounding ground-glass opacity in the left upper lobe of the lung (Figure 1(b)).
Histological examination of a lung biopsy specimen at low (a) and high (b) magnifications, showing pleomorphic giant tumor cells with poor cohesiveness. No apparent differentiation toward adenocarcinoma, squamous cell carcinoma, or neuroendocrine carcinoma was seen. Immunostaining showed that the tumor cells were positive for expression of CAM5.2 (c) and PD-L1 (d).
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Microscopically, the biopsy specimens were almost entirely composed of pleomorphic giant tumor cells with poor cohesiveness, with some of these cells being multinucleated (Figures 2(a) and 2(b)). Immunostaining showed that the biopsy specimens were positive for expression of cytokeratin CAM5.2 (Figure 2(c)), but negative for all other markers examined, including thyroid transcription factor 1, napsin A, p40, chromogranin, synaptophysin, CD56, and human chorionic gonadotropin beta subunit. However, PD-L1 expression was positive in a high proportion of tumor cells (tumor proportion score (TPS), 75%; Figure 2(d)) by immunostaining using a companion diagnostic kit, PD-L1 IHC 22C3 pharmDx Dako (Agilent, Santa Clara, CA, USA).
Diameters of the primary tumor before starting treatment with pembrolizumab (a and d), and after two (b and e) and four (c and f) cycles of treatment.
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The chest X-ray on admission (Figure 3(a)), as well as the CT scan three weeks before the admission (Figure 3(d)), showed rapid enlargement of the primary tumor, compared with assessments at the initial visit. The lung nodule measured 32 x 23 mm after two pembrolizumab cycles (6 weeks) (Figures 3(b) and 3(e)) and 24 x 16 mm after four cycles (12 weeks) (Figures 3(c) and 3(f)).