Renal cell carcinoma producing alpha-fetoprotein (AFP) with a unique lectins-affinity profile

Hepatoid differentiation in renal cell carcinoma: a rare histologic pattern with clinical significance

Hepatoid adenocarcinoma is a rare extrahepatic aggressive tumor defined by morphologic and immunohistochemical evidences of hepatoid differentiation. In this study, clinicopathologic features of 3 cases of hepatoid renal cell carcinoma (RCC) were analyzed. Case I was a 53-year-old man with stage III, with 1,460 ng/ml of serum alpha-fetoprotein (AFP) and a 12 cm-sized stage III RCC, which was a combined clear cell and papillary RCC type 2 with sarcomatoid dedifferentiation. Case II was a 62-year-old woman with stage IV, 6.5-cm clear cell RCC and 40,800 ng/mL of serum AFP. Case III was a 51-year-old woman with stage I, 1.6-cm Xp11 translocation RCC and 313.3 ng/mL of serum AFP. Cases I and II died of the disease at 26 and 21 months after radical nephrectomy, respectively. Case III was alive without the disease for 20 months at the last follow-up. Microscopically, three cases show hepatoid carcinoma areas with eosinophilic to clear cells, arranged in trabeculae, separated by thin sinusoidal vessels, in addition to diagnostic features of corresponding RCC subtypes. The tumor cells in these hepatoid carcinoma areas as well as at least focally in RCC areas were immunopositive for AFP in all three cases, but were immunonegative for other hepatic markers (Hep Par1, polyclonal CEA, and glypican 3). This report suggests that the hepatoid features with AFP production are aberrant differentiation that can be developed in various RCC subtypes. Recognizing hepatoid RCC will help explain abnormal elevation of serum AFP levelS, which can be used as a serum surveillance marker.

Tornado extraction: a method to enrich and purify RNA from the nephrogenic zone of the neonatal rat kidney

BACKGROUND

Development of the kidney is a complicated and tightly regulated process. Although several genes responsible for the renal development have been identified to date, the precise mechanisms of spatial and temporal regulation remain to be elucidated. Therefore, expanding our knowledge of molecules that are associated with nephrogenesis will be helpful to understand the whole process.

METHODS

To extract RNA selectively from the nephrogenic zone of the developing kidney, we developed a simple and reliable method.

RESULTS

This method, named "tornado extraction," enriched RNA of the nephrogenic zone by about 30-fold. In combination with the suppression subtractive hybridization, a considerable number of genes that were differentially expressed in the nephrogenic zone were obtained. These genes included a series of endodermal markers such as albumin and alpha-fetoprotein as well as GDNF (glia-derived neurotrophic factor), osteoblast-specific factor-2 (OSF-2)/periostin and fetuin (one of the major serum proteins in the fetus).

CONCLUSION

Tornado extraction has great value in studying genes in the nephrogenic zone of the developing kidney. Since the quality of RNA obtained by this method is excellent, tornado extraction is suitable in combination with other techniques including the subtractive hybridization method and DNA microarray analysis.

Differences between human and mouse alpha-fetoprotein expression during early development

Alpha-fetoprotein (AFP) is the major serum protein during development. AFP is one of the earliest proteins to be synthesised by the embryonic liver. The synthesis of AFP decreases dramatically after birth and only trace amounts are expressed in the adult liver. The tissue distribution of AFP in early human embryogenesis has not been defined. We have studied the expression pattern of AFP mRNA in human and mouse embryos by in situ hybridisation. In humans, AFP is expressed in the hepatic diverticulum at 26 d postovulation as it differentiates from the foregut endoderm (i.e. in the most primitive hepatocytes). It is also expressed in the endoderm of the gastrointestinal tract and in the yolk sac at this age. AFP is subsequently expressed in the mesonephros and transiently in the developing pancreas. In the mouse, no expression of AFP was observed in the mesonephros but other sites of expression were similar. Thus AFP has a distinct temporospatial expression pattern during the embryonic period and this differs between human and mouse species. It is interesting that AFP is expressed by tumours such as primitive gastrointestinal, renal cell and pancreatic tumours as well as those of hepatocyte origin. This distribution reflects the sites of AFP expression during development.

Diagnostic value of albumin gene expression in liver tumors: case report and review of the literature

Management of a solitary liver mass necessitates reliable distinction between primary hepatocellular carcinoma and metastatic lesions. The histologic differentiation can be difficult even with special stains such as alpha-fetoprotein, cytokeratin, and carcinoembryonic antigen. Albumin is a specific product of hepatocytes, and in situ hybridization to reveal albumin messenger RNA (mRNA) is highly specific and sensitive for the diagnosis of primary hepatocellular carcinoma. This technique can be used on histopathologic specimens and in cytologic diagnosis. Herein we describe a patient with synchronous renal and hepatic masses, in whom the distinction had to be made between metastatic renal cell carcinoma and two separate primary tumors--one in the liver and one in the kidney. In situ hybridization for albumin mRNA proved helpful in making this distinction. In addition, we review the literature on the diagnostic use of albumin gene expression in liver tumors.

Carcinoma of the stomach with hepatocyte differentiation (hepatoid adenocarcinoma)

A case of hepatoid adenocarcinoma of the stomach is reported, and the literature is reviewed. The stomach is one of the most common sites in which hepatoid adenocarcinomas have been detected. Of the 59 cases reviewed from the literature (including the current case), a 2:1 male predominance was noted, and the serum alpha-fetoprotein level was almost always increased. All patients were adults, and most had evidence of metastases at the time of resection. Prognosis seems less favorable than that associated with the more common intestinal type of adenocarcinoma of the stomach. Hepatoid adenocarcinomas typically show periodic acid-Schiff-positive, diastase-resistant intracytoplasmic globules, which are demonstrated to be positive with antibodies to alpha-fetoprotein. The tumor cells resemble liver cells, and rare cases, including our own, have evidence of bile production. In our case, messenger RNA for albumin, unique to liver cells, was demonstrated by in situ hybridization of the tumor cells.

Ovarian endometrioid tumors with yolk sac tumor component, an unusual form of ovarian neoplasm. Analysis of six cases

The clinical, morphological, and immunohistochemical findings in six cases of ovarian endometrioid tumors (five endometrioid carcinomas and one carcinosarcoma) with a yolk sac tumor (YST) component are described. The age of the patients ranged from 31 to 73 years (average, 53), and only two patients were premenopausal. Two cases were stage Ia tumors, three stage III, and one stage IV. A substantial postoperative elevation of alpha-fetoprotein (AFP) was seen in two patients and a mild increase in another two. All six patients had surgery and postoperative cisplatin-based chemotherapy regimens, four of whom died of tumor 3 to 14 months after surgery without response to treatment. Only a stage Ia patient is alive and well 1 year after surgery. The tumors were large (average, 17 cm). Benign endometrioid lesions were found in the homolateral ovary in two cases and in the contralateral ovary in another two. All cases had endometrioid ovarian carcinomas (EOC) of various types admixed with typical YST components. Immunohistochemically, EOC areas differed from YST in their positivity for OC 125, CA 19.9, and nuclear estrogen and progesterone receptors and in their negativity for AFP, which was conspicuously positive in the YST areas. The clinicopathological profile of ovarian endometrioid tumors with YST also differs from that of YST in that it occurs in the same age range as EOC, it shows coexistence of benign endometrioid lesions, and it has a poor response to chemotherapy. The histological pattern in transitional areas may be difficult to differentiate from "endometrioid-like" (enteroblastic) YST and clear cell tumors. Ovarian endometrioid tumors with YST component should be considered a variant of endometrial carcinoma. Its recognition is necessary in view of its unusually aggressive behavior and poor prognosis.