Table 2.
Histopathological features of the included articles
| Author (year of publication) | Main histological findings suggestive of neuroendocrine carcinoma | Histological type |
|---|---|---|
| Hayashi et al. (1987) | Diffuse proliferation of undifferentiated small cells. Cellular irregularity and mitotic figures are prominent | Small cells |
| Yoshida et al. (1995) | Solid sheets of small, undifferentiated cells, with hyperchromatic nuclei and scanty cytoplasm infiltrating the underlying muscle. Many mitotic figures were also observed | Small cells |
| Kim and Jang (2001) | Tumor arranged in solid nests and sheets, with absence of a fibrovascular stroma. Marked cellular pleomorphism associated with a crush artifact, and cellular necrosis, hyperchromatic oval to spindle shaped nuclei, and abundant mitosis were noted | Small cells |
| Noguchi et al. (2002) | Tumor nests of small cells surrounded by fibrous septa. The tumor cells showed a high nucleo/cytoplasmic ratio, and the nuclei were round or oval and hyperchromatic, with frequent mitotic figures | Small cells |
| Oku et al. (2002) | The tumor was composed of larger cells than those of small cell carcinoma and exhibited solid, trabecular, and slightly rosette-like growth patterns with a high mitotic rate in normal subepithelial interstitial tissue | Small cells |
| Güler et al. (2005) | Tumor cells with narrow cytoplasm and hyperchromatic nucleus | Small cells |
| Torazzi et al. (2007) | Diffuse and solid growth pattern, with small, monotonous, round neoplastic cells, scant cytoplasm and hyperchromatic nuclei | Small cells |
| Nishihara et al. (2009) | Invasive growth of the tumor; it appeared as a small ‘blue cell’ tumor that formed sheets and nests with artificially crushed cells, necrosis and stromal fibrous septa. The tumor cells had round to fusiform nuclei with fine granular chromatin and inconspicuous nucleoli. Mitotic figures were frequently observed at an average of 12 per high power field | Large cells |
| Mochizuki et al. (2010) | Solid nests of basaloid cells with scant cytoplasm, periphery palisading, extensive necrosis, rosette-like structures. The tumor cells showed a dot- like pattern for AE1/AE3 | Large cells |
| Chen et al. (2012) | Scattered small foci of tumor cells with a cicatrized fibrous stroma in the muscle adipose tissue | Small cells |
| Cymerman et al. (2013) | Focal undifferentiated small cell like appearance. High power view of undifferentiated small cell like morphology | Small cells |
| Terada (2013) | Small epithelial cells with hyperchromatic nuclei, molded nuclei, scant nucleocytoplasmic ratio, and negative nucleoli | Small cells |
| Yoshino et al. (2013) | Densely clustered, small round cells with large nuclei | NI |
| Bothara et al. (2014) | NI | Large cells |
| Singla et al. (2014) | Frequent mitoses and apoptotic necrosis | Small cells |
| Wu et al. (2014) | Round cells that grew in small nests and trabeculae | NI |
| Round cells that grew in sheets, with extensive necrosis | NI | |
| Esmati et al. (2015) | Solid pattern that composed of rather uniform cells with eosinophilic cytoplasm and mild hyperchromatic nuclei, without keratinization pearl | NI |
| Gumusay et al. (2015) | Darkly stained nuclei with small but conspicuous nucleoli and moderate to scant cytoplasm, mitotic figures, and a central area of necrosis | Small cells |
| Hamamoto et al. (2015) | Poorly differentiated tumor with large alveolar structure and invasive growth to the subcutaneous tissue. The tumor cells had large, irregular-shaped nuclei, with enlarged nucleoli and eosinophilic granular cytoplasm observed, and showed partial necrosis. The tumor cells consisted of polygonal shaped cells and spindle shaped cells. The mitotic rate of the tumor was relatively low | Large cells |
| The tumor consisted of polygonal cells showing solid growth. However, undifferentiated cells with alveolar configuration were also observed. The mitotic rate was very high | NI | |
| The tumor consisted of polygonal tumor cells, which showed a high nuclear/cytoplasmatic ratio and a high mitotic rate, with solid alveolar growth and myxomatous stroma. The tumor cells showed a partial duct-like configuration filled with Alcian Blue-periodic acid-Schiff-positive mucus materials, with neutrophils infiltrate observed inside of, and around, the tumor alveolar structure | NI | |
| The tumor consisted of polygonal shaped and undifferentiated tumor cells showing solid growth with cobblestone appearance, and ulcer formation was observed. Most of the tumor cells were medium sized and had oval-round nuclei with increased chromatin and a high nuclear/cytoplasmatic ratio. Some scattered large tumor cells with abnormal mitosis were observed, and the mitotic rate was very high | Large cells | |
| Zeng et al. (2015) | Small cells with ovoid‑ to spindle‑shaped nuclei, fine granular chromatin, inconspicuous nucleoli and scant cytoplasm. The tumor cells were arranged in solid nests, sheets and cords, with frequently occurring brisk mitotic figures and areas of necrosis | Small cells |
| Sase et al. (2016) | Growth of small, round, atypical cells lacking in cytoplasm is seen under the epithelium | Small cells |
| Deyhimi et al. (2017) | Nests and sheets of small round cells with round to oval nuclei, and scant eosinophilic cytoplasm. Pleomorphism, atypia, hyperchromatism, and mitotic figures were visible to variable degrees | Small cells |
| Udompatanakorn et al. (2018) | Small round to oval atypical cells arranged in nests with a glandular-like-pattern, hyperchromatic molded nuclei, a high nuclear-to-cytoplasmic ratio, and a scant eosinophilic cytoplasm | Small cells |
| Olivetto et al. (2019) | Undifferentiated tumor proliferation, of trabeculated architecture, composed of small basophilic cells with a high nuclear-cytoplasmic ratio. The nuclei are quadrangular, hyperchromatic | Small cells |
| Neftah et al. (2020) | Cellular proliferation made of layers of small granular chromatin cells with nuclear molding | Small cells |
NI not informed