Osler Institute – Pathology Board Review: Electron Microscopy
EM of Tumors and Tumor-Like Entities
Osler Institute – Pathology Board Review: Electron Microscopy
Acinar Cell Carcinoma
• Zymogen granules 0.3 – 1.5 microns• Stacks of RER • Salivary gland• Pancreas• Pancreaticoblastoma• Immunopositive for
alpha-1 antitrypsinTrypsinChymotrypsinLipase
Adenocarcinoma – extracellular lumina, intestinal type microvilli
Osler Institute – Pathology Board Review: Electron Microscopy
Osler Institute – Pathology Board Review: Electron Microscopy
Neoplasms
Adenocarcinoma• Intracytoplasmic lumina• Microvilli• Junctional complexes
Neoplasms
Osler Institute – Pathology Board Review: Electron Microscopy
Electron Microscopy - Osler Institute Pathology Board Review
Neoplasms
Bronchioloalveolar Cell carcinoma
Type II Pneumocyte• Myelin figures• Microvilli
Clara Cells• Secretory granules
Electron Microscopy - Osler Institute Pathology Board Review
Neoplasms
Carcinoid (Neuroendocrine) Tumors
• Dense core granules140 – 400 nm
• True lumens• Intracytoplasmic
filaments
Electron Microscopy - Osler Institute Pathology Board Review
Eosinophilic Granuloma
Langerhan’s cell histiocyte
• Rod shaped Birbeck Granule• Pleomorphic, deeply cleaved
nucleus
Electron Microscopy - Osler Institute Pathology Board Review
Neoplasms
Ependymoma• 5 – 7% of intracranial
neuroglial neoplasms• 60% of neuroglial tumors
in spinal cord• Most common sites –
fourth ventricle and lumbosacral region
• Flexner type rosettesTrue lumens – cilia, microvilli and junctional complexes
Electron Microscopy - Osler Institute Pathology Board Review
Neoplasms
Ependymoma
• Junctional complexes• Intracytoplasmic lumina• Intracytoplasmic glial
filaments• Immunopositive for GFAP
Electron Microscopy - Osler Institute Pathology Board Review
Neoplasms
Granular Cell Tumor
• Pleomorphic secondary lysosomes
• Basal lamina around cell groups
Electron Microscopy - Osler Institute Pathology Board Review
Neoplasms
Granular Cell Tumor
• Angulate lysosomes in stromal fibrohistiocytic cells
Electron Microscopy - Osler Institute Pathology Board Review
Neoplasms
Hibernoma
• Lipid droplets• Electron dense
mitochondria• S-100 protein +• Vimentin +
Electron Microscopy - Osler Institute Pathology Board Review
LymphomaNon Hodgkin's Type
• No junctional complexes• Few cytoplasmic
organelles• Abundant polyribosomes
Electron Microscopy - Osler Institute Pathology Board Review
LymphomaNon Hodgkin's Type
• No junctional complexes• Few cytoplasmic
organelles• Abundant polyribosomes
Electron Microscopy - Osler Institute Pathology Board Review
Neoplasms
Mesotheliomas
• Long thin microvilli• Bipolar cytoplasmic processes• Desmosomes• Primitive junctions• Calretinin +• Mesothelin +
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