Myelinoid lamellated cytoplasmic inclusions in human renal adenocarcinomas: an ultrastructural study

Mucin-secreting clear cell renal cell carcinoma. A rare variant of conventional renal cell carcinoma

We report herein one case of conventional renal cell carcinoma (RCC) producing extensive extracellular mucinous secretion in a 71-year-old man. To the best of our knowledge, the presence of mucinous secretion in this tumor has not been documented. Mucin production, despite its low frequency, can be considered an additional feature of conventional RCC. Therefore, clear cell RCC should be added to the list of parenchymal renal tumors that can show significant mucin secretion; and it should be included in the inventory of morphologic variations of this tumor, which may cause diagnostic difficulties. It is of primary importance to distinguish mucin-secreting clear cell RCC from the metastasis of a mucin-secreting tumor to conventional RCC. Presence of mucin in a clear cell carcinoma does not exclude a renal origin.

Eosinophilic cytoplasmic inclusions in papillary renal cell carcinoma

A case of a patient with papillary renal cell carcinoma (RCC) with eosinophilic inclusions is presented. Almost all neoplastic cells contained eosinophilic globules that were stained red by trichrome and were negative for periodic acid-Schiff (PAS) reaction. Immunohistochemically, globules were negative for actin, keratin, vimentin, glially fibrillary acidic protein (GFAP), and neurofilament. Ultrastructurally, globules consisted of electron-dense granular material that is more suggestive of a secretory substance than cytoskeletal filaments. The presence of eosinophilic cytoplasmic inclusions in RCC is rare. In this article, we review similar cases in the literature and discuss the nature of eosinophilic globules.

Clear cell renal cell carcinoma

Clear cell RCC is the most common type of RCC that occurs in adults. It has the worst prognosis among the common epithelial tumors of the kidney. Histologically, a wide range of morphologic patterns can be encountered. Those cases with a multi-locular cystic architecture are considered to be a distinct subtype because of the clinicopathologic features.

Collecting duct carcinoma exhibiting diastase-resistant PAS-positive globular cytoplasmic inclusions and rhabdoid features arising in adult polycystic kidney disease: a case report

A 76-year-old man complained of lumbago, and a subsequent detailed examination revealed a mass in the left kidney. Macroscopically, multiple cysts were recognized in the bilateral kidney; the tumor proliferated predominantly in the renal medulla and showed a whitish color with focal necrosis and hemorrhage. A histologic examination of the surgically resected tumor showed various growth patterns, such as solid, tubular, and papillary, by tumor cells. The diagnosis of collecting duct carcinoma (CDC) was made. Furthermore, tumor cells contained globular inclusions resembling hyaline globules and large eosinophilic inclusions, resulting in rhabdoid features, in the cytoplasm. Histochemically, globular inclusions were positive for periodic acid-Schiff (PAS) with diastase pretreatment. Immunohistochemically, large esosinophilic inclusions were reactive for vimentin. Although these findings are rare in CDCs, they should be recognized in the pathologic spectrum of CDCs. Int J Surg Pathol 12(2):171-177, 2004

Electron microscopy of large cell undifferentiated and giant cell tumors

Electron microscopy is a valuable morphologic method for the diagnostic evaluation of undifferentiated tumors composed of polygonal or oval large cells and mononuclear or multinucleated giant cells. Although few ultrastructural details are pathognomonic, electron microscopic findings may add significantly to the formulation of the final diagnosis if used in the context of other pathomorphologic and clinical data. Contributions of electron microscopy to tumor diagnosis are summarized and illustrated with appropriate examples from personal experience in a routine university hospital laboratory.

Collecting duct origin of rat renal clear cell tumors

The renal tubular segment from which clear cell tumors originate was investigated in the kidneys of rats treated with N-nitrosomorpholine. This tumor type, which in the rat closely resembles that in man, is made up of clear and granular acidophilic cells and arises from tubules lined by clear cells. The tubular origin of the tumors was established in serial sections by demonstrating connections between both clear cell tumors and tubules lined by clear cells, and renal tubules of normal appearance. In 45 clear cell lesions (17 tumors and 28 tubules) one or more such connections were identified which belonged to the collecting system. In accordance with their localisation in the kidney, the clear cell lesions were connected predominantly to tubules of the cortical collecting system and occasionally to outer medullary collecting ducts. As previously reported, oncocytic tubules and microoncocytomas were observed to originate from the same portions of the collecting system. Rarely, microadenomas and tubules consisting of both oncocytes and clear or granular acidophilic cells were also observed in the kidneys studied.