Electron Microscopy in an Oncologic Institution. Diagnostic Usefulness in Surgical Pathology

A retrospective survey of all electron microscopic (EM) examinations of surgical pathology specimens obtained at the Istituto Nazionale Tumori of Milan over a 5-year period (1981-1985) was carried out. During this time a total of 259 cases were examined: for 97 (38%) electron microscopy provided a substantial diagnostic contribution, whereas in 151 (58%) it confirmed the previous light microscopic diagnosis. In our experience, EM was most useful for diagnosing selected cases of cutaneous malignant melanoma predominantly metastatic, rhabdomyosarcoma, neuroblastoma and poorly differentiated neuroepithelial tumors and less helpful in the further analysis of cases of malignant mesothelioma, Ewing's sarcoma, leiomyosarcoma and fibrohistiocytic malignancies. In cases of well-differentiated neuroepithelial tumors, such as carcinoids, EM data was essentially confirmatory of (immuno)-histochemical findings.

Pulmonary adenocarcinoma with intestinal-type differentiation

A 44-year-old woman with a long history of smoking presented with a single lung mass detected on routine chest radiographs. There were no other known primary tumors. Light microscopy showed a mucin-producing adenocarcinoma of bronchioloalveolar type. Furthermore, no gastrointestinal primary has been discovered 18 months after discovery of the lung tumor. Electron microscopy revealed that tumor cells had microvilli containing abundant microfilamentous, dense-core rootlets that showed long extensions into apical cytoplasm. The microvilli were capped by numerous glycocalyceal bodies. These findings are similar to the ultrastructural features previously described as being specific for gastrointestinal adenocarcinomas metastatic to lung. The current case, however, suggests that the findings of glycocalyceal bodies and microvillous dense-core rootlets are not helpful in distinguishing between primary and metastatic lung adenocarcinomas.

"Anemone" cell (villiform) tumor of the brain

At age 31, the patient developed hydrocephalus secondary to a brain lesion that had been present for 12 years. A ventriculoperitoneal shunt was performed, but a stereotactic biopsy did not establish a definitive diagnosis at that time. At age 34 the patient experienced spontaneous intratumoral and ventricular hemorrhage, which prompted radical surgical resection of the lesion. Histologic and immunocytochemical findings established a diagnosis of ependymoma; review of the ultrastructure of the tumor from the biopsy performed when the patient was 31 years old revealed the characteristics of an "anemone" cell neoplasm.

Correlation of ultrastructural aberrations with dysplasia and flow cytometric abnormalities in Barrett's epithelium

Barrett's esophagus develops as a complication of chronic gastroesophageal reflux and predisposes patients to the development of dysplasia and adenocarcinoma of the esophagus. Because light microscopy of dysplasia in Barrett's esophagus shows diminished or absent mucus, we used transmission electron microscopy to compare cytoplasmic organelles required for mucus production in dysplastic and nondysplastic esophageal columnar epithelium. These observations of the rough endoplasmic reticulum, Golgi apparatus, and secretory granules were correlated with histologic interpretations and flow cytometric measurements of abnormalities of DNA content. Ultrastructural abnormalities included depletion and alteration of organelles required for mucus biosynthesis. These abnormalities often were accompanied by cells with markedly distended rough endoplasmic reticulum and massive accumulation of cytoplasmic glycogen aggregates. All 9 patients who had Barrett's dysplasia with or without early adenocarcinoma had ultrastructural abnormalities, as did 3 of 8 patients whose biopsy histology was indefinite for dysplasia. Abnormalities measured by flow cytometry correlated well with the presence of these ultrastructural aberrations. All 9 patients with Barrett's dysplasia with or without early adenocarcinoma had abnormalities observed by electron microscopy and aneuploidy or increased G2/tetraploid fractions measured by flow cytometry. Two of the 3 patients whose biopsies were indefinite for dysplasia and who had ultrastructural abnormalities also had aneuploidy or increased G2/tetraploid fractions. Neither ultrastructural nor flow cytometric abnormalities were found in the remaining 5 patients whose biopsies were indefinite for dysplasia, in 19 of 22 patients with Barrett's specialized metaplasia, or in any of the 7 patients with gastroesophageal reflux disease without Barrett's specialized metaplasia. Two of the 22 patients with Barrett's specialized metaplasia had distended rough endoplasmic reticulum in rare cells, and one other had an aneuploid cell population. We conclude that neoplastic progression in Barrett's esophagus is associated with abnormalities of cytoplasmic organelles required for mucus production. With few exceptions, these ultrastructural aberrations correspond to the presence of dysplasia or of aneuploidy or increased G2/tetraploid fractions. Electron microscopy and flow cytometery detect abnormalities associated with the development of dysplasia and cancer in Barrett's esophagus that may be biologically significant.

Limitations of the usefulness of microvillous ultrastructure in distinguishing between carcinoma primary in and metastatic to the lung

We performed ultrastructural analysis on 70 consecutive patients with solitary cancers in lung with the following histologic classifications: adenocarcinoma (42 cases), bronchioloalveolar carcinoma (13), large cell carcinoma (4), and adenosquamous carcinoma (11). Of these 70 cases, nineteen (13 adenocarcinomas, 4 bronchioloalveolar carcinomas, and 2 adenosquamous carcinomas) contained cell surface microvilli with microvillous core rootlets and/or glycocalyceal bodies. Subsequent clinical followup revealed that three of these 19 cases were actually metastatic colon carcinoma. The remaining 16 patients are currently free of extrathoracic primary disease and are therefore, presumably, primary carcinoma of the lung. Since both primary and metastatic tumors showed cell surfaces with microvilli having core rootlets and glycocalyceal bodies, we conclude that the presence of these ultrastructural features does not always permit the distinction between primary and metastatic adenocarcinoma in lung.