PMC4602839_01
(A) Chest radiograph upon admission to our hospital showing a well-defined nodular shadow in the right middle lung field. (B) Chest computed tomography scan showing a well-defined, round, solid nodule of 10 mm size, located in the right segment 6.
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F1
A 57-year-old, asymptomatic woman with no history of smoking was referred to our hospital after a chest radiograph revealed a nodular shadow in the right middle lung field (Figure 1A). Chest computed tomography (CT) showed a well-defined, round, solid nodule, which was 10 mm in diameter, in segment 6 of the right lung (Figure 1B).
(A) Macroscopically, a jelly-like tumor is located in the lung parenchyme. (B) A paucicellular and avascular tumor with cuffs of inflammatory cells observed in the alveolar space. (C) Multivacuolated tumor cells with microcytic change and lymphoid cuffs are visible. (D) The tumor shows minimal destruction of the alveolar structure (elastic Van-Gieson staining). (E) The nuclei of the tumor cells show minimal atypia, with focal and mild pleomorphism (hematoxylin and eosin staining). (F) Intracellular and intracystic mucin accumulation is noted (alcian-blue/periodic acid-Schiff staining).
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F2
Macroscopically, the resected sample contained a homogeneous, jelly-like transparent tumor, 10 mm in maximum diameter, in the lung parenchyma (Figure 2A). Histologically, the tumor was well demarcated and paucicellular and it consisted of large tumor cells with a low nuclear/cytoplasmic ratio and prominent intracellular vacuolation (Figure 2B). Cuffs of lymphocytes and minimal destruction of the alveolar structure were observed at the periphery of the tumor (Figure 2C and D). However, some of the tumor cells were irregular in shape and had larger nuclei (Figure 2E); neither mitotic figures nor vascular invasion was observed. A myxoid substance was observed in the cytoplasm of vacuolated tumor cells and microcystic space on alcian-blue staining, which also stained the adjacent alveolar spaces (Figure 2F).
(A) Brachyury immunostaining showing focal expression and brachyury-positive expression in the tumor cell nuclei. (B) Referenced conventional axial chordomas showing diffuse brachyury-positive expression in the nucleus. (C) Similar to axial benign notochordal cell tumors, tumor cells showing diffuse positive expression for epithelial markers including cytokeratin AE1/AE3. (D) Vimentin expression is diffusely positive in tumor cells. (E) Positive expression of thyroid transcription factor-1 is only visible in pneumocytes entrapped at the margin of the tumor. (F) Cluster of differentiation 68 expression was completely negative in tumor cells, but infiltration in the alveolar macrophages at the periphery can be observed.
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F3
On immunohistochemical staining, brachyury, a highly specific diagnostic marker of notochordal differentiation, was focally but undoubtedly positive in the nuclei of the tumor cells (Figure 3A). The results showed that the ratio of brachyury-positive cells in the present case (14%) was much lower than that of the control chordoma cases (90%-98%, mean 93.3%) (Figure 3B). CK), CAM5.2 (low-molecular-weight CK), vimentin, S100 protein, CK7, CK18, and CK19 (Figure 3C and D). Conversely, the tumor cells were negative for CK5/6, CK20, thyroid transcription factor-1, napsin A, cluster of differentiation (CD) 68, and CD163 (Figure 3E and F).