PMC5749379_01
Responses of a CD74-ROS1 fusion patient with pulmonary blastoma to crizotinib.. Notes: Computed tomography scans of the chest were obtained at baseline and after 1 month of treatment with crizotinib. (A) Chest computed tomography revealed a soft tissue mass in the left upper lobe abutting the anterior-lateral pleura. (B) Computed tomography of the chest at 1 month after receiving crizotinib treatment displayed significant left lung lesion shrinkage compared to baseline. The patient achieved PR with 34.4% shrinkage of tumor size. The red marked up area indicates the size of tumor lesion.. Abbreviation: PR, partial response.
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Chest computed tomography scan revealed a mass with its largest diameter measuring 5.8 cm, located in the left upper lobe and extending into the chest wall with pleural invasion and rib metastases (Figure 1). She achieved reduction in pleural effusion and 34.4% shrinkage of tumor size, accompanied by alleviation of symptoms such as coughing, thoracalgia and dyspnea (Figure 1).
Photomicrographs showing the representative histologic appearance of pulmonary blastoma.. Notes: (A) Malignant epithelial elements in undifferentiated mesenchymal stroma stained by H&E (200x). (B) The malignant glandular component was diffusely positive for the epithelial marker CK (40x). (C) The stromal blastematous malignant component was diffusely positive for mesenchymal stromal marker vimentin (100x). The yellow arrows indicate the positive cells stained by relevant markers.. Abbreviations: CK, cytokeratin; H&E, hematoxylin-eosin.
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The mesenchymal component consisted of round and shuttle cells with atypia nuclear and visible karyokinesis; in contrast, the epithelial component consisted of tubular and glandular structures (Figure 2A). Immunohistochemistry showed the tubular epithelial component to be positive for epithelial marker cytokeratin and negative for vimentin, while the mesenchymal blastematous malignant component showed reverse expression (negative cytokeratin, diffusely positive for vimentin), as shown in Figure 2B and 2C.
The IGV screenshots display the reads from next-generation sequencing and reveal harbouring of CD74-ROS1 fusion.. Note: Intron 7 of CD74 is joined with intron 33 of ROS1.. Abbreviation: IGV, Intergrative Genomics Viewer.
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Our data revealed the presence of CD74-ROS1 rearrangement, joining intron 7 of CD74 with intron 33 of ROS1, with an allelic fraction of 43.6% (Figure 3).