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. 2026 Jul 22;19(1):1312–1322. doi: 10.1159/000553555

Fig. 2.

Immunohistochemical staining was performed on paraffin-embedded sections using the Ventana BenchMark Ultra immunostainer with the ultraView Universal DAB Detection Kit and antibodies against INSM1, Cytokeratin AE1/AE3, Chromogranin A, Ki-67, p40, S100, and Desmin. A: Columns of tumor tissue with solid structures formed by atypical small cells with scant amphophilic cytoplasm and oval hyperchromatic nuclei; occasional mitotic figures, including atypical forms, and numerous apoptotic bodies. B: Positive reactions in tumor cells with monoclonal antibodies to INSM1, Cytokeratin AE1/AE3 (diffuse strong perinuclear dot-like cytoplasmic staining), and Chromogranin A (focal strong cytoplasmic staining). Negative reactions for p40, S100 and Desmin. C: Ki-67 proliferation index = 100%.

Histopathology examination. Immunohistochemical staining was performed on paraffin-embedded sections using the Ventana BenchMark ULTRA immunostainer with the ultraView Universal DAB Detection Kit and antibodies against INSM1, cytokeratin AE1/AE3, chromogranin A, Ki-67, p40, S100, and desmin. a Columns of tumor tissue with solid structures formed by atypical small cells with scant amphophilic cytoplasm and oval hyperchromatic nuclei; occasional mitotic figures, including atypical forms; and numerous apoptotic bodies. b Positive reactions in tumor cells with monoclonal antibodies to INSM1, cytokeratin AE1/AE3 (diffuse strong perinuclear dot-like cytoplasmic staining), and chromogranin A (focal strong cytoplasmic staining). Negative reactions for p40, S100, and desmin. c Ki-67 proliferation index = 100%.