Histology (A) and immunohistochemistry (B and C). (A) Neoplastic lesion composed of intermediate-sized oval or ovoid cells with nuclei showing fine granular chromatin, exhibiting mild cytological atypia, and possessing pink cytoplasm. These cells form an ‘organoid’ pattern within thin fibrous septa (zellballen pattern). Dilated small blood vessels are observed. No areas of necrosis are present. (B and C) The neoplastic cells show positivity for CD56, synaptophysin, chromogranin, and S-100, while being negative for CKAE1-AE3, PAX-8, and PAGF. The vascular marker CD31 highlights the presence of small capillary vessels. The proliferation index KI-67 is <2%. The histological and immunophenotypic profile is consistent with a non-malignant neuroendocrine neoplasia, resembling a paraganglioma.