PMC5399212_01
Fine-needle aspiration biopsy of the abdominal mass revealed tumor nests consisting of small round tumor cells with scanty cytoplasm, round-to-oval nuclei, finely dispersed chromatin, and inconspicuous nucleoli (A: Hematoxylin and Eosin staining, original magnification, x20). An immunohistochemical evaluation showed the small round tumor cells to exhibit membranous and paranuclear dot-like staining with cytokeratin 20 (B: x20) as well as neuroendocrine markers consisting of chromogranin A (C: x20), CD56, and synptophysin (data not shown) and negative staining for thyroid transcription factor 1 (D: x20), indicating a neuroendocrine carcinoma.
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Endoscopic ultrasound-guided fine-needle aspiration biopsy was performed for a histological examination, showing tumor nests of small round cells with scanty cytoplasm, round-to-oval nuclei, finely dispersed chromatin, and inconspicuous nucleoli (Fig. 1A). The tumor cells were diffusely positive for cytokeratin 20 (CK 20) in a dot-like paranuclear pattern (Fig. 1B), in addition to being positive for neuroendocrine markers, including the cluster of differentiation (CD) 56 (neural cell adhesion molecule), NSE, and chromogranin A (Fig. 1C). In contrast, the tumor cells were negative for thyroid transcription factor 1 (TTF-1) (Fig. 1D) and leukocyte common antigen (LCA).
CT scans of the abdomen just before the start of amrubicin administration (A) and at the completion of two cycles of amrubicin treatment (B) showing tumor shrinkage from a maximum diameter of 144 down to 92 mm. The tumor remained progression-free for 9 months.
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A second CT scan obtained at this time showed further enlargement of the abdominal lesion to a size of 144 mm (Fig. 2A). The serum NSE levels returned to normal, and a partial response was achieved after two cycles had been administered (Fig. 2B).