Embryonic ultrastructure as a guide in the diagnosis of tumors

Our plain-English summary of Embryonic ultrastructure as a guide in the diagnosis of tumors, by G.R. Dickersin (Ultrastructural Pathology, 1987).

The study

• Author: G.R. Dickersin
• Journal: Ultrastructural Pathology
• Published: 1987;11(5-6):609-52
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The purpose of this article has been to illustrate the applications and limitations of comparing the ultrastructural morphology of certain poorly differentiated neoplasms with normal human embryonic tissues. The examples used--embryonal rhabdomyosarcoma, Wilms' tumor, and fibrous mesothelioma, in comparison with embryonic mesoderm and its early derivatives--are but a few of the entities that can be investigated in this manner. Ewing's sarcoma was included in the report because of the long-standing and unsolved mystery concerning its histogenesis and because we believe it probably fits into the same category of poorly differentiated mesodermal neoplasms as the other lesions described. However, unlike the other more definite examples of primitive neoplasms manifesting focal markers of secondary mesenchymal differentiation, Ewing's sarcomas exhibit no ultrastructural evidence for myogeneous, nephrogenic, or mesothelial lines of maturation. Nor are there any morphologic indications of ectodermal or endodermal differentiation. The questions arise as to whether the category of Ewing's sarcoma has been perpetuated by so classifying all small-cell neoplasms having no recognizable line of differentiation, and whether this category may include cells of more than one type, that is, cells that are biologically determined to develop along several different pathways. This concept would be one explanation for the occurrence of Ewing's tumors in soft tissue as well as in bone, and we know that the cells contained in somites are ultrastructurally very similar to the least-differentiated cells making up the myotomes and sclerotomes. Apparently, questions such as these cannot be answered by morphologic studies alone. However, a number of other useful diagnostic and academic points of information can be gleaned.

In plain English

This article compared normal tissues from human embryos with several poorly differentiated tumors under the electron microscope. Embryos came from spontaneous abortions, and embryonic parts came from elective abortions. The article does not say how many tumors were examined. Embryonic muscle-forming tissue (the myotome) showed a range of development similar to embryonal rhabdomyosarcoma. However, a high percentage of the tumor cells had more cytoplasm and organelles, and more irregular nuclei, and finding muscle markers often took patient searching. Embryonic kidney-forming tissue closely resembled the undifferentiated parts of Wilms' tumors, but tumor tubules never reached the maturity of normal tubules in the late embryo and fetus. Cells beneath the embryonic body-cavity lining bore some resemblance to the tumor called "fibrous mesothelioma", also called solitary fibrous tumor of the pleura. Ewing's sarcoma showed no ultrastructural sign of muscle, kidney or mesothelial maturation. The article does not discuss asbestos. The author concluded that questions such as the origin of Ewing's sarcoma cannot be answered by morphologic studies alone, though other useful diagnostic information can be gained.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: descriptive electron-microscopic comparison of normal human embryonic tissues with poorly differentiated tumors
• Who was studied: Several human embryos from spontaneous abortions (including an intact 39-day-old embryo), embryonic parts from elective abortions, and various tumors (number not stated): embryonal rhabdomyosarcoma, Wilms' tumor, fibrous mesothelioma and Ewing's sarcoma
• Exposure: No asbestos or other exposure was studied; the article compares the microscopic structure of tissues
• Main results:
  • In all the skeletal-muscle-type tumors seen, a high percentage of tumor cells had more cytoplasm and organelles than cells of the embryonic myotome, and the tumors had deeply indented nuclei with moderate heterochromatin
  • Most embryonal rhabdomyosarcomas studied were made up mainly of cells without thick filaments and Z-band material, so finding these muscle markers often needed patient searching and more sampling
  • The embryonic metanephric blastema closely resembled the undifferentiated parts of Wilms' tumors, but tumor tubule differentiation never reached that of normal late embryo and fetus
  • Subsurface cells of the embryonic coelomic lining bore some resemblance to cells of fibrous mesothelioma (also termed spindle-cell mesothelioma or solitary fibrous tumor of the pleura)
  • Ewing's sarcomas showed no ultrastructural evidence of muscle, kidney or mesothelial lines of maturation
• The authors' conclusion: The author concluded that questions about the origin and classification of Ewing's sarcoma cannot be answered by morphologic studies alone, but that other useful diagnostic and academic information can be gained
• Limitations the authors state:
  • Primitive cells of different lineages may look alike until they reach a certain maturity, so the specific lineage of very immature tumors may be impossible to establish
  • Only a few tumor glomeruloid structures were available for ultrastructural study

Topics

Medical terms in this study, explained in our Lexicon: Neoplasm, Mesothelioma, Mesoderm, Sarcoma, Standing.

Related studies

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• Pleural malignant mesothelioma following Wilms' tumor — M.B. Austin, R.E. Fechner, et al. (1986)
• Endothelioma (mesothelioma) of the pleura; presentation of a case treated surgically — L.A. Hochberg, I.G. Epstein, et al. (1947)
• Unusual cases: melanomatosis and nephroblastomatosis treated with hyperthermic intraperitoneal chemotherapy — A. Hayes-Jordan, H. Green, et al. (2012)
• Mesothelial cell differentiation into osteoblast- and adipocyte-like cells — S.M. Lansley, R.G. Searles, et al. (2011)
• A new insight into the histogenesis of 'mesodermomas'--malignant mesotheliomas — A. Donna, P.G. Betta, et al. (1991)

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