PMC9683475_01
Radiographic and pathological images of Case 1. (A, B) A computed tomography (CT) scan at first visit showing a left lung mass with lung window and mediastinum window. (C) Biopsy specimens of the left lung mass revealed malignant cells with adenoid structure, abundant cytoplasm, eosinophilic, and round nuclei, suggesting infiltrating adenocarcinoma of the left lung (H&E staining, x200 magnification). (D) Immunohistochemical (IHC) staining revealed transcription termination factor 1 (TTF-1) immunopositivity (TTF-1 staining, x 100 magnification). (E) CT scan showing progression of left pulmonary lesions after 14 months of gefitinib use. (F) CT scan showed multiple nodules and masses in the left lung. The lesions were increased, enlarged and fused compared with 5 months ago. Multiple enlarged lymph nodes were seen, and multiple metastasis was considered. (G) Biopsy after mass resection revealed malignant cells, which were small, round, and arranged in small nests, with minimal cytoplasm and hyperchromic nuclei (H&E staining, x200 magnification). (H) IHC staining revealed diffuse strong positive expression of CD56 in cancer cells (CD56 staining, x100 magnification). Morphology and immunohistochemistry were consistent with small cell lung cancer.
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A computed tomography (CT) scan revealed a 3.3x2.5 cm mass in the lower left lung and multiple mediastinal lymph nodes ( Figures 1A, B ). After percutaneous puncture lung biopsy, the removed tissues were diagnosed pathologically by immunohistochemistry (IHC) and hematoxylin-eosin (H&E) staining ( Figure 1C ). IHC staining results indicated that both CK7 and napsin A were expressed in the cytoplasm and were strongly positive, while thyroid transcription factor 1 (TTF-1) was expressed in the nucleus and was positive ( Figure 1D ). CT scan results that were compared with previous 9-month images revealed partial enlargement of the left lung lesion and a large pleural effusion on the left side ( Figure 1E ). Review of the chest CT compared to those obtained in August 2021 revealed progression of the lesion in the left lung, with multiple lymph node and organ metastases ( Figure 1F ). Biopsy was performed after the resection of a 2.0x1.5 cm tumor section on the left chest wall ( Figure 1G ).
PMC9683475_02
Case presentation of transformation of lung squamous cell carcinomas to small cell lung carcinoma with pembrolizumab. (A, B) Chest CT scan showing a space-occupying lesion of the left hilar with mediastinum window and lung window. (C, D) Biopsied specimens subjected to IHC staining showed that P40 was strongly positive, and Syn was negative (P40 and Syn staining, x100 magnification). (E) Based on resected specimens, the pathological diagnosis was lung squamous cell carcinoma (H&E staining, x200 magnification). (F, G) The patient was treated with a regimen of ICIs combined with chemotherapy and exhibited a partial response. The lesion was significantly reduced in the mediastinum window and lung window than before treatment. (H, I) After completing 15 cycles of immunotherapy, CT scans revealed tumor progression and new lesions in the left lower lung in the mediastinum window and lung window. (J, K) IHC staining revealed strong Syn immunopositivity in the cytoplasm and negative staining for P40 (Syn and P40 staining, x100 magnification). (L) Biopsy resulted in tumor diagnosis of small cell lung cancer (H&E staining, x100 magnification). Rx, treatment; CT, computed tomography; H&E, hematoxylin and eosin; CBDCA, carboplatin; TAX, paclitaxel; Syn, synaptophysin.
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Figures 2A, B ). Fiberoptic bronchoscopy revealed complete blockage of the upper lobe opening of the left lung. The specimens were biopsied under bronchoscopic guidance with strong positive IHC staining for P40 ( Figure 2C ) and P63 in the nucleus, and positive expression of CK5/6 and CK7 in the cytoplasm. Specimens were negative for TTF-1 in the nucleus and for napsin-A and Syn ( Figure 2D ) in the cytoplasm. Even cornified pearls were observed in H&E sections ( Figure 2E ). The patient was treated for NSCLC with ICIs combined with chemotherapy and exhibited a partial response ( Figures 2F, G ). Compared to the CT findings in May 2021, a follow-up CT scan revealed tumor progression, metastases, and new lesions in the left lower lung ( Figures 2H, I ). Syn ( Figure 2J ) and CK7 in the cytoplasm. The Ki-67 positive index was 40%. Staining for P40 ( Figure 2K ), P63, napsin-A, and CK5/6 was negative. Biopsy revealed consistent characteristics with SCLC ( Figure 2L ).