The main structures observed were tunica albuginea, interstitial cells, germinative epithelium, sustentacular
cells, and spermatogonias.
The chief cells are strongly and diffusely immunoreactive with chromogranin and synaptophysin, while the supporting sustentacular
cells react with S-100 protein (figure 2).
There is great overlap in the immunohistochemical staining pattern of these entities, particularly between paraganglioma and carcinoid tumors where presence or absence of S100-positive sustentacular
cells may be the only clue.
The cells were synaptophysin-positive, and the sustentacular
cells were highlighted on S-l00 and glial fibrillary acidic protein staining.
S100 protein is typically used to highlight the sustentacular
network in paragangliomas; however, the reactivity pattern is usually variable.
Sustentaculoma arises from sustentacular
cells of the adrenal medulla and may be the closest histologic mimic of adrenal schwannoma.
This can present a pitfall in differentiating a spindle cell carcinoid from mesenchymal tumors and a nested carcinoid from paraganglioma (NE markers are expressed in both, but S100-positive sustentacular
cells are typical of paraganglioma but not carcinoid tumors).
(26,28) These are composed of chief cells and sustentacular
cells in a nesting or zellballen pattern.
(25) Pheochromocytoma has the characteristic Zellballen microscopic pattern, with well-defined nests of tumor cells supported by sustentacular
(5,24) In contrast to the intraluminal polypoid mass for metastatic clear cell RCC of the gallbladder, paraganglioma appears as a small, well-circumscribed nodule protruding to the external surface of the gallbladder and is composed of chief and sustentacular
cells arranged in a zellballen pattern.
(56,57) The presence of a nested zellballen growth pattern, including identification of sustentacular
cells and a sinusoidal vascular pattern, are key to a correct diagnosis.
In addition, characteristic S100 protein staining limited to the periphery of the neoplastic lobules (sustentacular
cell-like staining pattern) is present, although such S100 protein staining diminishes with increased histologic grade, and in higher-grade ONBs it may be extremely limited in extent or absent (Figure 6).