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

A spontaneous middle ear adenocarcinoma characterized by abundant eosinophilic matrix in a young male Crl:CD(SD) rat

A mass was detected in the right tympanic cavity of a 15-week-old male Crl:CD(SD) rat. Histological examination revealed papillary or tubular proliferations of epithelial cells including ciliated cells that produce mucus and have an abundant eosinophilic matrix. The malignancy of this tumor was revealed by its destructive proliferation, cellular polymorphism, and high proliferative activity. The tumor was diagnosed as a middle ear adenocarcinoma due to its location and histological characteristics. This is the first report of a middle ear adenocarcinoma in rats and the first middle ear tumor accompanied by eosinophilic matrix observed in either humans or animals. The eosinophilic matrix was positive for periodic acid-Schiff and periodic acid-silver methenamine stains and for laminin and collagen Type IV, immunohistochemically, but negative for Congo red, which suggested that this matrix was a basement membrane substance.

SWI/SNF chromatin remodeling and human malignancies

The SWI/SNF complexes, initially identified in yeast 20 years ago, are a family of multi-subunit complexes that use the energy of adenosine triphosphate (ATP) hydrolysis to remodel nucleosomes. Chromatin remodeling processes mediated by the SWI/SNF complexes are critical to the modulation of gene expression across a variety of cellular processes, including stemness, differentiation, and proliferation. The first evidence of the involvement of these complexes in carcinogenesis was provided by the identification of biallelic, truncating mutations of the SMARCB1 gene in malignant rhabdoid tumors, a highly aggressive childhood cancer. Subsequently, genome-wide sequencing technologies have identified mutations in genes encoding different subunits of the SWI/SNF complexes in a large number of tumors. SWI/SNF mutations, and the subsequent abnormal function of SWI/SNF complexes, are among the most frequent gene alterations in cancer. The mechanisms by which perturbation of the SWI/SNF complexes promote oncogenesis are not fully elucidated; however, alterations of SWI/SNF genes obviously play a major part in cancer development, progression, and/or resistance to therapy.

Hyalinizing Pancreatic Adenocarcinoma in Six Dogs

Exocrine pancreatic carcinoma is a particularly malignant neoplasm of the dog. Clinical and pathologic findings of an unusual variant of exocrine pancreatic neoplasia termed hyalinizing pancreatic adenocarcinoma were evaluated in 6 dogs. On microscopic examination, neoplasms were composed of tubules and acini of epithelial cells, with bright eosinophilic granular apical cytoplasm. Tubular lumina and tumor stroma contained abundant hyaline material that resembled amyloid. The hyaline material was not congophilic, and tumor cells and hyaline material were immunohistochemically negative for amyloid A, immunoglobulin light chains (κ and λ), amylin (islet amyloid polypeptide), laminin, and α1-antitrypsin. Two patients survived longer than 15 months after diagnosis; one of these dogs was untreated and had grossly evident metastasis at the time of diagnosis. The deaths of the other 4 dogs occurred as a result of poor recovery after partial pancreatectomy or in association with other concurrent life-threatening conditions. Two dogs were diagnosed with panniculitis, a condition rarely associated with pancreatic disease. Further evaluation is needed to determine the composition and biologic significance of intratumor hyaline material. Studies that associate exocrine pancreatic carcinoma grade and histologic subtype with prognostic outcomes in the dog are warranted such that appropriate therapy can be elected.

Intraoperative cytology of clear cell carcinoma of the ovary

OBJECTIVE

To describe the cytomorphology of clear cell carcinoma (CCC) of the ovary in intraoperative samples of peritoneal fluid, imprint and scraping samples of the tumour tissue.

STUDY DESIGN

Fourteen histologically confirmed cases, stained by standard cytological procedures, were analysed by light microscopy.

RESULTS

In 33.3% of peritoneal fluid samples and 92.9% of imprint and scraping cytological samples, besides variable clear cell cellular morphology, one or both distinct cytological characteristics were observed: eosinophilic, hyaline, extracellular, globular substance with or without formation of a 'raspberry' body and an eosinophilic, intracytoplasmic inclusions. These structures were clearly seen only in samples stained by May-Grünwald-Giemsa.

CONCLUSION

Using cytological analysis of imprint and scraping samples of ovarian tumours it is possible to make a precise intraoperative cytological diagnosis in most cases of CCC of the ovary.

Carcinoma in situ of the cystic duct

Cholelithiasis and cholesterolosis associated with carcinoma in situ of the cystic duct epithelium was observed in a male patient. Ultrastructurally, small acini-like lined a thickened, reduplicated basal lamina encompassing a pleiomorphic population of cells, including typical cholecystocytes, a poorly differentiated type, and cells containing modified mucous vesicles with heterogeneous fatty deposits. Even though the etiology of this apparent neoplastic epithelium and of its thickened basal lamina is unclear, it is hypothesized to be the result of an altered control of cell adhesion mechanisms, resulting from a repeated renewal of the typical epithelium abraded by the passage of the stones and the biliary sludge, associated with inflammatory stimuli that accompany cholecystolithiasis. Based on recent studies, it is suggested that investigations of molecular markers in extrahepatobiliary tract lesions and retrospective studies of these archival tissues could clarify the association of these neoplastic changes with other hepato-biliary lesions.

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.