Difference between revisions of "Neuromuscular pathology"

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Neuromuscular pathology (view source)

Revision as of 21:03, 30 September 2021

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m
Primary biliary cholangitis (newer term - replaces 'primary biliary cirrhosis')
(→‎Inflammation: update list)
m (Primary biliary cholangitis (newer term - replaces 'primary biliary cirrhosis'))
 
(31 intermediate revisions by one other user not shown)
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** Formalin -> for IHC.
** Formalin -> for IHC.
** 4% Glutaraldehyde fixed -> for electron microscopy.
** 4% Glutaraldehyde fixed -> for electron microscopy.
====Skin biopsies====
* Punch biopsies (3mm) for small fiber neuropathy.
** Paraformaldehyde-lysine-periodate -> for PGP9.5 immunofluorescence.


=Muscle structure/histology=
=Muscle structure/histology=
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===General===
===General===
Etiology:<ref>{{Cite journal  | last1 = Prieto-González | first1 = S. | last2 = Grau | first2 = JM. | title = Diagnosis and classification of granulomatous myositis. | journal = Autoimmun Rev | volume = 13 | issue = 4-5 | pages = 372-4 | month =  | year =  | doi = 10.1016/j.autrev.2014.01.017 | PMID = 24424169 }}</ref>
Etiology:<ref>{{Cite journal  | last1 = Prieto-González | first1 = S. | last2 = Grau | first2 = JM. | title = Diagnosis and classification of granulomatous myositis. | journal = Autoimmun Rev | volume = 13 | issue = 4-5 | pages = 372-4 | month =  | year =  | doi = 10.1016/j.autrev.2014.01.017 | PMID = 24424169 }}</ref>
* [[Sarcoidosis]]
* [[Sarcoidosis]].
* Idiopathic
* Idiopathic.
* Infectious ([[Tuberculosis]], Syphillis, Brucellosis
* Infectious ([[Tuberculosis]], Syphillis, Brucellosis.
* Foreign-body reaction
* Foreign-body reaction.
* [[Thymoma]] - myasthenia gravis
* [[Thymoma]] - myasthenia gravis.
* [[Lymphoma]] - paraneoplastic
* [[Lymphoma]] - paraneoplastic.
* [[Primary biliary cirrhosis]]
* [[Primary biliary cholangitis]].


<gallery>
<gallery>
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===General===
===General===
*Most common biopsy: sural nerve.
*Most common biopsy: sural nerve.
**Approx. 20-30% of the biopsies are diagnostic or may alter treatment decisions.
** Far less common: Superficial peroneal nerve.
*Metabolic, toxic and nutritional causes account for 50% of neuropathies.
*Metabolic, toxic and nutritional causes account for 50% of neuropathies.
*Inflammatory neuropathies (mostly GBS, CIDP or vasculitis): 10-20%.
*Inflammatory neuropathies (mostly GBS, CIDP or vasculitis): 10-20%.
*Familial neuropathy: 10-20%.
*Familial neuropathy: 10-20%.
*Neoplasm-associated neuropathy: 5-10%.
*Neoplasm-associated neuropathy: 5-10%.
===Nerve structure===
*Nerve (surrounded by epineurium).
*Fascicle (surrounded by perineurium).
** Usu 6-15 fascicles in sural nerve.
*Nerve fibre (surrounded by endoneurium).
**Myelinated axons.
**Unmyelinated axons and their Schwann cells together are called Remak bundles.
Epineurium:
* Capillaries, arterioles and venules.
* Fibroblasts (CD34+/-ve, EMA-ve, S100-ve).
* Macrophages (CD68+ve, CD168+ve).
* Mast cells (metachromatic granules).
* Leukocytes (usu. less than 10 CD3+ve Lymphocytes/mm²).
* Pacinian corpuscles (no pathological relevance).
Perineurium:
* Fascicles may separated by perineurial septae.
*Occasional perineurial calcifications (no pathological relevance).
*Renaut bodies (subperineurial whorled structures consisting of fibroblasts).
<gallery>
Image:N_renaut_body_semithin.jpg|Renaut body in a fascicle.
File:Pacinian Corpuscle (36298105211).jpg|Pacinian corpuscle.
</gallery>


===Stains===
===Stains===
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*Axon = green.
*Axon = green.
*Myelin = red.
*Myelin = red.
Toluidine blue staion:
*Plastic embedded semithin sections (1µm).
===Artifacts===
*Myelin splits: stretching.
*Neurokeratin: Formalin fixation (longitudinal: "herringbone", cross section: "wagon-wheels").
*Dark staining myelin: crushing.
*Pale expanding myelin sheets: delayed fixation.
*Uneven myelin staining: osmication problems.
*Shrunken crescentic fascicles: Hyperosmolarity.


===Reactive changes===
===Reactive changes===
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===Degenerative changes===
===Degenerative changes===
Types:<ref>URL: [http://missinglink.ucsf.edu/lm/ids_104_musclenerve_path/student_musclenerve/nervepath.html http://missinglink.ucsf.edu/lm/ids_104_musclenerve_path/student_musclenerve/nervepath.html]. Accessed on: 9 November 2010.</ref>
Types:<ref>URL: [http://missinglink.ucsf.edu/lm/ids_104_musclenerve_path/student_musclenerve/nervepath.html http://missinglink.ucsf.edu/lm/ids_104_musclenerve_path/student_musclenerve/nervepath.html]. Accessed on: 9 November 2010.</ref>
*Wallerian degeneration.
*Axonal degeneration.
*Axonal degeneration.  
*Wallerian degeneration.  
*Segmental demyelination.  
*Segmental demyelination.  
====Axonal degeneration====
*Axonal swelling.
*Intra-axonal filamentous aggregates.
*Mitochondrial abnormalities.
*Aggregation of organelles and dense bodies.


====Wallerian degeneration====
====Wallerian degeneration====
*Watery axon and granular disintegration (distal).
*Macrophage accumulation (3-4d after transsection).
*Many lysosomes (CD68+ve).
*Endoneurial proliferation.
*Digestion chambers - '''key feature'''.
*Digestion chambers - '''key feature'''.


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</gallery>
</gallery>


===Regeneration===
*Axon sprouts (regenerating clusters): Three or more closely apposed myelinated axons.
*Thin myelin sheaths.


===Inflammation===
===Inflammation===
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*[[Leprosy]] (Leprous neuropathy).
*[[Leprosy]] (Leprous neuropathy).
*[[Sarcoidosis]].
*[[Sarcoidosis]].
*Neuropathy with macrophage-induced demyelination (CIDP, GBS).
*CMV neuritis in immuncompromised patients.
*CMV neuritis in immuncompromised patients.
*[[Vasculitis]].
*[[Vasculitis]].
*Paraprotein-associated neuropathy.
*Neuropathy with macrophage-induced demyelination (CIDP, GBS).
====Guillain–Barré syndrome====
*Acute inflammatory demyelinating polyneuropathy (AIDP)
*Preceding infection (RSV, EBV, CMV, HIV, Mycoplasma).
*Monophasic course of motor / sensory deficits.
*Hours to 4 weeks.
*Elevated CSF protein but normal cell count.
*Mononuclear ednoneurial perivascular inflammatory infiltrate (mostly CD4+ve).
*Destructive myelin stripping by macrophages.
*Reduced fiber density.
*Uncompacted myelin / Widely spaced myelin.
====Chronic inflammatory demyelinating polyneuropathy (CIDP)====
*Progredient course longer than 8 weeks.<ref>URL: [http://path.upmc.edu/cases/case426.html http://path.upmc.edu/cases/case426.html]. Accessed on: 14
November 2010.</ref>
*Progressive or relapsing and remitting course.
*Multifocal affections of proximal nerves (motor and sensory symptoms).
*Responsive to steroids.
*Enlargement of affected nerve.
*Variation of fiber density between fascicles / reduced axon numbers.
*CD4+ve/CD8+ve inflammatory infiltrates(approx. 65% cases).
*Demyelination (thinly myelinated axons, macrophages).
*Onion-bulb formations (15-40%, chronic recurrent demyelination and remyelination).
DDx: Familial hypertrophic neuropathy.
====Neurosarcoidosis====
*Neurological symptoms in 5% of sarcoidosis cases.
*Granulomas may be endoneurial or epineurial.
*Compact mass of epitheloid cells.
*Perilesional fibrosis and lymphocytic infiltrates.
*Axonal loss and regenerating fibers.
*Segmental demyelination and remyelination.
====Vasculitic neuropathy====
*Endoneurial and epineurial mircrovessels, arterioles and venules.
*Ischemia of nerve: thrombosis and fibrinoid necrosis.
*Signs of previous vasculitis: Vessel narrowing, fragmentation of elastica, fibrous obliteration and recanalization.
*Often nerve involvement in systemic vasculitis:
**Medium-sized epineurial vessels: mostly classic polyarteritis nodosa.
**Small and medium-sized vessels and eosinophilia: Churg-Strauss angitis.
**Small vessels and necrotizing: ANCA-associated microscopic polyangitis.


<gallery>
<gallery>
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===Other Diseases===
===Other Diseases===
*Guillain–Barré syndrome.
*Amyloid neuropathy: Amorphic endoneurial deposits.
*Chronic inflammatory demyelinating polyneuropathy (CIDP).<ref>URL: [http://path.upmc.edu/cases/case426.html http://path.upmc.edu/cases/case426.html]. Accessed on: 14 November 2010.</ref>
**TTR amyloidosis is of specific interest, because treatment options exist.<ref>{{Cite journal  | last1 = Adams | first1 = D. | last2 = Koike | first2 = H. | last3 = Slama | first3 = M. | last4 = Coelho | first4 = T. | title = Hereditary transthyretin amyloidosis: a model of medical progress for a fatal disease. | journal = Nat Rev Neurol | volume = 15 | issue = 7 | pages = 387-404 | month = Jul | year = 2019 | doi = 10.1038/s41582-019-0210-4 | PMID = 31209302 }}</ref>
**Essentially chronic Guillain–Barré syndrome.
**Example of amyloid deposits [https://www.nature.com/articles/s41582-019-0210-4/figures/3 here]
*Neuropathy associated with paraproteinemia: Alterations in myelin periodicity, nerve fiber loss.
**[[MGUS]] - Monoclonal gammopathy of unknown significance.
** Multiple myeloma.
**[[POEMS]] syndrome.
**[[LCDD]] - light chain deposition diesease.
*Toxic polyneuropathy (drug toxicity).<ref>URL: [http://path.upmc.edu/cases/case173.html http://path.upmc.edu/cases/case173.html]. Accessed on: 8 January 2012.</ref>
*Toxic polyneuropathy (drug toxicity).<ref>URL: [http://path.upmc.edu/cases/case173.html http://path.upmc.edu/cases/case173.html]. Accessed on: 8 January 2012.</ref>
 
*Polyglucosan body disease.


===Neoplasms===
===Neoplasms===
Michael
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