Unusual intracytoplasmic lamellar bodies in a malignant gonadal stromal tumor

Ultrastructure of pheochromocytoma: undescribed morphologic features

We examined samples of human pheochromocytoma from 11 patients aged 30-70 years including one case of malignant pheochromocytoma with a view to identifying previously unreported ultrastructural details.We identified two types of nuclear inclusions consisting of irregularly shaped singular or multiple granulofibrillar formations with a typical concentric halo, on the one hand, and accumulations of egg-shaped structures consisting of granules and microfilaments, on the other. In some of the tumor cells, membrane-covered inclusions containing parallel laminar elements arranged in a paracrystalline, periodic fashion, or mega-mitrochondriae characterized by increased electrodensity of their matrix, and fibrillary material in the spaces between the cristae were present. A frequent finding consisted of typical ciliary formations, while rough/smooth tubular aggregates of different size occurred less frequently. Finally, we were able to demonstrate the uptake of norepinephrine by smooth muscle fibers in the periphery of arterial vessels as evidenced by linear accumulations of membrane-covered granules separating bands of contractile smooth muscle components in the peripheral layers of arterial vessels close to norepinephrine producing neoplastic cells.These findings represent ultrastructural features that contribute to further elucidating the ultrastructural characteristics of the human pheochromocytoma.

Ultrastructure of hyaline, border, and vacuole cells in chick inner ear

The sense organ for hearing in birds, the basilar papilla, is capable of replacing lost or damaged hair cells and supporting cells through regeneration. Potential candidates for precursor-cell populations include cells within the auditory receptor epithelium and nonsensory cells inferior to the sensory epithelium. Ultrastructural characteristics of hyaline cells, border cells, and vacuole cells, nonsensory cells which border or lie inferior to the receptor epithelium proper, were studied with transmission electron microscopy. Data were obtained from normal neonatal and adult chickens. Several rows of epithelial cells separate hyaline cells from inferiorly located organ supporting cells and hair cells. Ultrastructural characteristics and location of these epithelial cells differentiate them from organ supporting cells and hyaline cells; consequently, we have termed them "border cells." Synaptic specializations are observed between neural elements and border cells, and gap junctions are found between adjacent border cells, between border cells and neighboring organ supporting cells, and between juxtaposed border and hyaline cells. Hyaline cells, in contrast to border cells, are highly specialized. Dense bundles of filaments are present in hyaline cells from the basal one-half of the papilla, and an unusual structure, a rough tubular aggregate, is present in hyaline-cell cytoplasm. Pre- and postsynaptic specializations are observed between neural elements and hyaline cells, and gap-junctional complexes link neighboring hyaline cells. Vacuole cells lie inferior to the hyaline cells and rest on the inferior fibrocartilaginous plate. They are unspecialized morphologically. Their only remarkable morphological feature is the abundance of spherical vacuoles within their cytoplasmic matrix.

Papillary-cystic neoplasm of the pancreas

Papillary-cystic neoplasm of the pancreas is a rare tumor which has recently been described as a distinct, clinicopathological entity. Forty-four previously described cases from the literature and an additional 52 cases referred to in a brief abstract are reviewed. An additional case occurring in a 25-year-old woman is reported. This tumor occurs primarily in young women (mean age 23.3 years) and presents as a large abdominal mass (mean size 10.3 cm) in 63% of patients. Treatment is surgical resection of the involved portions of the pancreas and results of treatment are excellent following this form of therapy alone. The tumor appears to represent a low-grade malignancy, possibly of ductal cell origin. Only two patients with recurrences and two patients with metastatic disease have been reported. Surgeons should be aware of this curable pancreatic malignancy as they are most often responsible for the evaluation and treatment of the patient presenting with a large abdominal mass.

The role of immunohistochemistry, electron microscopy, and ultrastructural cytochemistry in the diagnosis of mixed carcinoma-neuroendocrine neoplasms

We studied four mixed carcinoma-neuroendocrine neoplasms from gastrointestinal tract and pancreas by routine light microscopy (LM), immunohistochemistry (IH), electron microscopy (EM), and ultrastructural cytochemistry (UC). By LM, the individual tumors showed fairly pure neuroendocrine (carcinoid) or epithelial (papillary) patterns, mixed neuroendocrine-carcinoma features and poorly-differentiated tumor in sheets and nests which did not lend itself to morphologic characterization. IH demonstrated mixed expression, within different areas of the same neoplasm, of epithelial antigens (keratins and carcinoembryonic antigen [CEA]) and neuroendocrine markers (neuron-specific enolase [NSE], bombesin and neurohormonal peptides). By EM, each tumor showed ultrastructural features of epithelial and neuroendocrine differentiation which varied substantially in terms of number of cells involved and their distribution; two of the neoplasms showed biphasic differentiation within single cells. The nature of the neurosecretory granules was verified with the uranaffin reaction (UR). This study illustrates the value of combining LM, IH, EM and UC for the identification of mixed carcinoma-neuroendocrine lesions.