Infantile hemangioendothelioma of the liver: ultrastructural study of a type II case

Infantile hemangioendothelioma with elevated serum alpha fetoprotein: report of 2 cases with immunohistochemical analysis

Infantile hemangioendothelioma is the most common benign mesenchymal tumor of the liver presenting during the first 6 months of life. Serum alpha fetoprotein is an important tumor marker for hepatoblastoma, hepatocellular carcinoma, and germ cell tumors. However, it is rarely elevated in patients with hepatic infantile hemangioendothelioma. In such cases, surgery may be done to rule out malignancies when alpha fetoprotein levels are high. The etiology of the elevated alpha fetoprotein level has not yet been elucidated. We report 2 cases of solitary hepatic infantile hemangioendothelioma and demonstrate immunohistochemically that hepatocytes near or entrapped within the tumor were the source of the increased serum levels of alpha fetoprotein explaining the unusual clinical presentation.

Basal lamina reduplication in malignant epithelioid pleural mesothelioma

Malignant mesothelioma of the pleura is divided in three morphological variants: epithelioid, sarcomatous, and biphasic. Histological similarities between epithelioid malignant mesothelioma (EMM) and lung adenocarcinoma are responsible for the difficult differential diagnosis. Monoclonal antibodies are useful for distinguishing the two neoplasms through immunohistochemical phenotyping, although many cases require ultrastructural characterization for definitive diagnosis. In this study, transmission electron microscopic observations of EMM were compared with those of peripheral adenocarcinoma of the lung (PAL). More specifically, the morphology of the basal lamina is described in 23 cases of EMM and 12 cases of PAL. Reduplication of the basal lamina (RBL) was found in 11 cases (48%) of EMM and in none of the PAL cases. The same cases were immunostained for type IV collagen and the localization of this basement membrane component corresponded to the areas where basal lamina was observed. Since RBL has been associated with neoplastic differentiation in other tumors, this novel feature in EMM needs to be evaluated in future prognostic studies in malignant mesothelioma of the pleura. Moreover, RBL expression in EMM may be an additional ultrastructural parameter used in the differential diagnosis between EMM and adenocarcinoma.

Reduplicated basal lamina in clear-cell carcinoma of the ovary: an immunohistochemical and electron microscopic study

Clear-cell carcinomas of the female genital tract are uncommon tumors that usually arise in the ovary, cervix, or vagina. The objectives of the present study were to examine the immunohistochemical and ultrastructural characteristics of 18 of these tumors and to determine whether any distinctive features were present at the different locations. The fine structure of the neoplastic cells was similar at the several sites but there was a striking difference in the appearance of the basal lamina. Prominent reduplication of the basal lamina was seen in all 7 ovarian carcinomas, whereas it was mild in 3 and absent in 7 of the cervico-vaginal tumors. The distribution of eosinophilic hyaline material in hematoxylin/eosin sections and of immunohistochemical staining for type IV collagen and larminin correlated with the ultrastructural observations. Reduplication of the basal lamina has been observed in a number of epithelial neoplasms and viewed as a criterion of differentiation, but there is currently no evidence that its presence influences the prognosis of clear-cell carcinomas of the ovary.

Hepatic hemangioendothelioma of infancy associated with elevated alpha fetoprotein and catecholamine by-products

Five cases of hepatic hemangioendothelioma (HH) were seen in infants ranging from 2 days to 5 months of age. The cases were studied by clinical chemistry, immunohistochemical staining, and electron microscopic techniques. Serum alpha-fetoprotein (AFP) levels were elevated in each of the four patients in whom levels were obtained. The highest elevation was noted in a 2-day-old infant with a diffuse, unresectable lesion involving the right lobe. Two patients who underwent complete resections of their solitary HH had normalization of their AFP levels. This study suggests that AFP levels in patients with HH are closely related to the patients' age, with the youngest patient having the highest levels of AFP. Catecholamine by-products (VMA and HVA) were elevated in one of four patients in whom levels were obtained, this infant was 3 months old at the time of presentation. She also had an elevated AFP level, a diffuse unresectable lesion involving the entire liver, multiple pulmonary nodules, and cutaneous hemangiomas. Immunohistochemical study failed to demonstrate the source of AFP or the catecholamine by-products in the tumor of this patient, suggesting that the source of catecholamine by-products could be stress-induced catecholamine secretion.