Banff '05 Meeting Report: differential diagnosis of chronic allograft injury and elimination of chronic allograft nephropathy ('CAN').

The 8th Banff Conference on Allograft Pathology was held in Edmonton, Canada, 15-21 July 2005. Major outcomes included the elimination of the non-specific term "chronic allograft nephropathy" (CAN) from the Banff classification for kidney allograft pathology, and the recognition of the entity of chronic antibody-mediated rejection. Participation of B cells in allograft rejection and genomics markers of rejection were also major subjects addressed by the conference.

Renal ablation with absolute ethanol. Mechanism of action.

The mechanism of renal ablation by intra-arterial ethanol was studied in 16 mongrel dogs. Ethanol injection rates were varied, and light and electron microscopic studies were performed to detect early parenchymal changes in the kidneys. Pure ischemic injury was also studied as a control. Findings showed extensive parenchymal injury plays a significant role in renal ablation with permanent thrombosis as a delayed event. Acute arterial occlusion occurred with slow ethanol injection rates due to embolization by damaged blood components.

Intraluminal calcium hydroxyapatite crystals in breast carcinoma: an ultrastructural study.

Sixty-three breast carcinomas were examined by electron microscopy to determine the frequency of calcium hydroxyapatite (apatite) within tumor lumina. Twenty-one adenocarcinomas contained apatite in intracytoplasmic and/or intercellular lumina. Well-differentiated tumors exhibited a higher incidence of apatite (44%), while only 20% of the poorly differentiated tumors contained apatite (gamma = +.22). There was no apparent correlation between the presence of apatite and a positive estrogen receptor assay. Ninety-eight adenocarcinomas of other than breast origin (previously processed for electron microscopy) were examined, revealing 2 cases containing apatite in the appropriate locations. The tissue of origin in one case was determined to be ovarian, while the origin of the second case remains undetermined. The ultrastructural finding of apatite in lumina of adenocarcinoma appears to be unusual in that it has only been observed in breast carcinomas and certain ovarian tumors. The presence of apatite within the lumen in addition to other characteristics of an adenocarcinoma may suggest the breast as the primary site.

Type II pneumocytes in pulmonary tumors. Implications for histogenesis.

Bronchioloalveolar carcinomas (n = 45), intravascular bronchiolo-alveolar tumors (n = 8), and sclerosing hemangiomas of the lung (n = 2) were stained for surfactant apoprotein by the immunoperoxidase method. Of the bronchiolo-alveolar carcinomas, 12 were found to be carcinomas of type II pneumocytes and the remaining 33 tumors were designated as nontype II pneumocytic bronchiolo-alveolar carcinomas. Twenty-five of these tumors displayed trapped benign type II pneumocytes within the tumor masses. In the case of intravascular bronchioloalveolar tumors, none of the tumors demonstrated staining of tumor cells for surfactant apoprotein. In the two cases of sclerosing hemangiomas, the type II pneumocytes were exuberant and numerous, and in one case contained intranuclear inclusions of surfactant apoprotein. This article discusses the implication of the presence of benign type II pneumocytes in pulmonary tumors.

Simple technique to facilitate tissue sampling for electron microscopy.

The need to examine certain components of a specimen with the electron microscope is frequently recognized only after study of the paraffin sections, by which time the total specimen has usually been fixed in Formalin. Such specimens are frequently large, with the result that representative samples for electron microscopy may be difficult to isolate. A simple, quick, and inexpensive method for overcoming this sampling problem is described. This technique is best employed in laboratories that routinely use a single tissue fixative suitable for both light and electron microscopy. The specimen is taken direct from the Formalin, and very thin slices are prepared by hand with a blade, stained with methylene blue, and examined in the wet state under the microscope. On identification, representative tissue is removed by micro-dissection and processed further for electron microscopy.

Pulmonary blastoma: an ultrastructural study emphasizing intestinal differentiation in lung tumors.

Features of intestinal differentiation, including the presence of brush borders, have been described previously in a pulmonary blastoma following xenotransplantation in athymic nude mice. This paper reports similar findings in a pulmonary blastoma subjected directly to electron microscopic study. Ultrastructural manifestations of intestinal differentiation in other types of primary lung tumors are also discussed.

Ablation of renal tumors with absolute ethanol: a new technique.

Transcatheter injection of absolute ethanol into the renal artery is an effective method of producing renal ablation. There has been no evidence of inadvertent damage to vessels or tissues remote from the target organ. The "postembolization syndrome" of pain, nausea, vomiting, and fever is minimal when compared with other methods of renal artery occlusion. Multiple mechanisms of action of intraarterial ethanol are proposed, including perivascular tissue toxicity, sludging of erythrocytes in small arteries, small artery spasm, and endothelial damage. Experience with this technique in six patients has resulted in specific recommendations regarding the amount and method of injection of ethanol. Angiographic criteria indicating adequate renal ablation are described.

Glycocalyceal bodies and their role in tumor typing.

Glycocalyceal bodies are membrane-bound vesicles found on the apical surface of intestinal epithelial cells and their neoplastic equivalents. They are believed to arise either from budding of the apical plasma membrane, through discharge from intracytoplasmic vesicles or through both of these mechanisms. Glycocalyceal bodies should be distinguished from particles of inspissated glycocalyceal material as well as from the vesicles that form following microvillous disintegration due to cell injury. There is also a superficial resemblance between glycocalyceal bodies and the membrane vesicles found among the lumen-lining microvilli in both normal and neoplastic sweat ductal epithelium. The chief value of glycocalyceal bodies in diagnostic electron microscopy lies in their role as a marker for intestinal differentiation in tumors. Their exact function is unknown.

Crystals in a gastric schwannoma.

A gastric schwannoma containing large numbers of intracytoplasmic crystals is described. The latter are compared with intracytoplasmic crystals found in the cells of other tumors and their nonneoplastic cell counterparts. The extreme morphologic and histochemical heterogeneity of the different types of crystals is emphasized.

Spinal melanotic clear-cell sarcoma: a light and electron microscopic study.

We report a melanotic spindle-cell tumor that arose from a thoracic spinal nerve root and metastasized to both lungs. The bulk of the tumor consisted of glycogen-rich clear cells and bore a striking resemblance on light and electron microscopy to at least one variant of the clear-cell sarcoma of tendons and aponeuroses. The presence of schwannoma-like areas noted in the primary tumor on light microscopy and the formation of a highly developed basal lamina noted on ultrastructural examination suggest that the tumor may be a partially dedifferentiated malignant melanotic schwannoma. This tumor is discussed in the context of a simple histogenetic classification of melanotic tumors.

Convoluted secretory material in thyroid follicular epithelial tumors.

Electron microscopy may occasionally be useful, when routine histopathologic methods fail, in the typing of tumors, including those that present as metastases from occult primary sites. We describe a case in which the presence of an uncommon ultrastructural feature aided in establishing the thyroid gland as the source of a skeletal metastatic tumor.

Glycocalyceal bodies and microvillous core rootlets: their value in tumor typing.

An ultrastructural study of the cell surface of lumen-forming tumors was carried out to determine the distribution of two morphologic markers seen in relation to the microvilli. These are membrane-bound glycocalyceal bodies and microvillous filament cores that penetrate the underlying cytoplasm as rootlets. They were found (especially when in combination) to be valuable in identifying tumors of what is referred to as intestinal-type epithelium, and could be seen in cases in which brush borders were absent. They have been demonstrated in intestinal-type carcinomas of the stomach and gallbladder, in adenocarcinomas of the small and large intestines and pancreatic ducts, in mucin-forming bronchiolar carcinomas, and in certain mucinous ovarian and endocervical tumors. Other tumors, whether mucin-producing or not, have been found to consistently lack these structures.

Ectopic renal cell carcinoma: pathologists problem.

Renal cell carcinoma (hypernephroma) rarely develops as a primary tumor outside the normal confines of the kidney. Although many reports of so-called extrarenal hypernephroma may be found in the literature, very few cases appear to fulfill modern criteria for tumors of true renal origin. Strict criteria for the diagnosis of true extrarenal hypernephroma are proposed, and a case that partially conforms to these standards is presented.

Meconium granulomas of the tunica vaginalis.

Meconium peritonitis results from perforation of the gastrointestinal tract during fetal life. Involvement of the tunica vaginalis may be the sole presenting clinical manifestation of the disease in the unusual event of the gut perforation resolving spontaneously. In such instances radiologically detectable calcification in the abdomen and scrotum is an essential diagnostic point. A case is described in which a baby had hydroceles and bilateral intrascrotal nodules but in which calcification was radiologically undetectable, presumably owing to its having undergon resolution. The typical histology of the nodules provided the diagnosis in this otherwise clinically undiagnostic case.