PMC6741564_01
Tumor lesions detected by PET-CT. (a). Before the start of TKI treatment: central lung tumor in the left lower lobe mass infiltrating the hilum and mediastinum and bilateral adrenal metastases; (b). Progression after 6 months of erlotinib: enlarged pleural mass that showed transformation to SCLC. (c) Partial response after four cycles of EP chemotherapy and erlotinib continuation: Dramatic shrinkage of the primary lung tumor.
kcbt-20-09-1617561-g001.jpg
PMC6741564_01_kcbt-20-09-1617561-g001.jpg
F0001
Positron emission tomography-computed tomography revealed fluoro-2-deoxy-d-glucose-positive lesion measuring 3.3 x 5.8 x 5.0 cm in the left lower lobe (Figure 1(a)). CT scan revealed an enlarged pleural mass measuring 3.8 x 4.0 x 5.0 cm (Figure 1(b)). He achieved PR after four cycles (Figure 1(c)) and developed disease progression (PD) with an enlargement of primary and metastatic lesions after a PFS of 7.7 months.
Variation curve of NSE, CEA, CA125, CA153, CYFRA21-1 and SCC. NSE, neuron-specific enolase; CEA, carcinoembryonic antigen; CA125, carcinoma antigen 125; CA153, carcinoma antigen 153; CYFRA21-1, cytokeratin 19 fragment antigen 21-1; SCC, squamous cell carcinoma antigen.
kcbt-20-09-1617561-g002.jpg
PMC6741564_01_kcbt-20-09-1617561-g002.jpg
F0002
Laboratory examinations revealed positive neuron-specific enolase (NSE) at 26.36 ng/mL, carcinoembryonic antigen at 3.99 ng/mL, and cytokeratin 19 fragment antigen 21-1 (CYFRA21-1) at 11.47 ng/mL in the serum (Figure 2). In addition, levels of NSE (26.03 ng/mL) and CYFRA21-1 (13.02 ng/mL) were also elevated (Figure2).
HE and IHC staining was performed on primary tumor biopsies after 6 months of erlotinib treatment. The cells displayed an SCLC phenotype with hyperchromatic nuclei, abundant cytoplasm, and inconspicuous nucleoli. Typical for SCLC, IHC was strongly positive for CD56 and TTF1, and focally for CK7 and synaptophysin (all 400x).
kcbt-20-09-1617561-g003.jpg
PMC6741564_01_kcbt-20-09-1617561-g003.jpg
F0003
Re-biopsy of the primary tumor revealed EGFR 19 del accompanied by SCLC transformation evident by positive expressions of CD56, TTF-1, CK7, and synaptophysin (Figure 3). H&E staining revealed typical SCLC histology consisting of nests of small cells (Figure 3).