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 +