Utility of Transmission Electron Microscopy in Small Round Cell Tumors

Abstract

Small round cell tumors (SRCTs) are a heterogeneous group of neoplasms composed of small, primitive, and undifferentiated cells sharing similar histology under light microscopy. SRCTs include Ewing sarcoma/peripheral neuroectodermal tumor family tumors, neuroblastoma, desmoplastic SRCT, rhabdomyosarcoma, poorly differentiated round cell synovial sarcoma, mesenchymal chondrosarcoma, small cell osteosarcoma, small cell malignant peripheral nerve sheath tumor, and small cell schwannoma. Non-Hodgkin’s malignant lymphoma, myeloid sarcoma, malignant melanoma, and gastrointestinal stromal tumor may also present as SRCT. The current shift towards immunohistochemistry and cytogenetic molecular techniques for SRCT may be inappropriate because of antigenic overlapping or inconclusive molecular results due to the lack of differentiation of primitive cells and unavailable genetic service or limited moleculocytogenetic experience. Although usage has declined, electron microscopy (EM) remains very useful and shows salient features for the diagnosis of SRCTs. Although EM is not always required, it provides reliability and validity in the diagnosis of SRCT. Here, the ultrastructural characteristics of SRCTs are reviewed and we suggest that EM would be utilized as one of the reliable modalities for the diagnosis of undifferentiated and poorly differentiated SRCTs.

Primary bilateral corneal nerve sheath neoplasm in a dog

“…In addition, transmission electron microscopy revealed discontinuous basal lamina, a feature of neurofibromas, and thread‐like cytoplasmic processes coated with basement membrane surrounded by an extracellular compartment of collagen, as in benign nerve sheath neoplasms . Similarly, malignant nerve sheath neoplasms are reported to display continuous reduplicated basal lamina and long‐spacing collagen (i.e., Luse bodies) similar to what was observed in the present case . A canine intraocular nerve sheath neoplasm was described to have neoplastic cells with poorly delineated cytoplasmic processes, distinct nucleoli, incomplete basement membrane‐like material, and desmosomes between adjacent cells, which are similar to our ultrastructural findings.…”

Seclidemstat blocks the transcriptional function of multiple FET-fusion oncoproteins

“…54,55 Abundant ribosomes are also seen in other small round blue cell tumors. 56 We also found upregulation of RNA processing genes and pathways related to replication, ssDNA binding and helicase activity. These pathways are consistent with changes in the biology of RNA processing as a result of loss of an allele of one of the RNA-binding FET proteins, and the subsequent alterations in RNA processing caused by interaction of the FET LCD with various RNA processing proteins, like RNA helicase A and the splicing machinery.…”

Hirnbasissyndrom infolge eines Tumors bei einer 17 Monate alten Deutsch-Holstein-Färse

“…Diese Bezeichnung wird für eine Gruppe schlecht differenzierter Tumoren angewandt, die sich in der Hämatoxylin-Eosin-Färbung basophil darstellen und deren Gewebeursprung in dieser Routinefärbung nicht detektiert werden kann. Zu diesen Tumoren gehören kleinzellige Lymphosarkome und Karzinome, schlecht differenzierte Neuroblastome und primitive neuroektodermale Tumoren (5,6).…”