Difference between revisions of "Microorganisms"

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==Fungi==
==Fungi==
{{Main|Fungi}}
*There are lots of 'em.  Below are a few of 'em.
*There are lots of 'em.  Below are a few of 'em.


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===Tissue invasive fungi===
===Tissue invasive fungi===
Typically:<ref>CM 17 Apr 2009.</ref>
Typically:<ref>CM 17 Apr 2009.</ref>
*Mucor
*Mucor.
*Aspergillus
*Aspergillus.


==Histoplasmosis==
===List===
*''Histoplasma capulatum'' - primative fungus, typical location: lung.
[[Histoplasmosis]]
** Often in yeast form in tissue 2-5 micrometres.<ref name=Ref_WMSP103>{{Ref WMSP|103}}</ref>
[[Coccidioidmycosis]]
** Nice bright red on PAS-D - [http://en.wikipedia.org/wiki/File:Histoplasma_pas-d.jpg histoplasmosis (wikipedia.org)].
[[Pneumocystis pneumonia]]  
*** Have a "central dot"<ref>URL: [http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/A6I001-PQ01-M.htm http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/A6I001-PQ01-M.htm]. Accessed on: 19 October 2010</ref> - [http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/PQ-Images/A6I001-3.gif histoplasma (ouhsc.edu)].
[[Cryptococcus]]
 
[[Cryptosporidiosis]]
==Coccidiomycosis==
[[Candidiasis]]
*''Coccidioides immitis'' - fungus, from soil, typical locations: lung, oral cavity.<ref name=Ref_WMSP3>{{Ref WMSP|3}}</ref>
[[Blastomycosis]]
** Forms spherules 60-80 micrometres in size.<ref name=Ref_WMSP103>{{Ref WMSP|103}}</ref>
[[Mucormycosis]]
** [http://commons.wikimedia.org/wiki/File:Mature_spherule_with_endospores_of_Coccidioides_immitis_PHIL_480_lores.jpg Coccidioides (commons.wikimedia.org)].
 
==Pneumocystis pneumonia (PCP) ==
*''Pneumocystis jirovecii'' (used to be called ''Pneumocystis carinii'') - fungus (that used to be considered a parasite), typical location: lung.
**Clinical: Opportunistic infection. May have subtle finding on chest x-ray.
**"Dented ping-pong ball" appearance;<ref name=Ref_WMSP103>{{Ref WMSP|103}}</ref> - remember '''P'''C'''P''' = '''p'''ing-'''p'''ong.
**Approximately 7-8 micrometres in size - [http://commons.wikimedia.org/wiki/File:Pneumocystosis_carinii_of_lung_in_AIDS_959_lores.jpg PCP (WP)].  [http://commons.wikimedia.org/w/index.php?title=Special%3ASearch&search=Pneumocystis+carinii&go=Go Several images are here (WC)].
 
==Cryptococcus==
*Usually ''C. neoformans'', fungus - opportunistic infection, typical location: lung.
*Most common fungus seen in CSF specimens.<ref name=Ref_APBR682>{{Ref APBR|682}}</ref>
 
Appearance:
*Yeast:
**Round/ovoid 5-15 micrometres (may resemble Histoplasma or Candida -- but often larger).
**Thick mucopolysacchardie capsule + refractile centre.<ref name=Ref_APBR682>{{Ref APBR|682}}</ref>
**"Tear drop-shapped" budding pattern (useful to differentiate from Blastomyces, Histoplasma).<ref name=Ref_APBR682>{{Ref APBR|682}}</ref>
 
Images:
*[http://commons.wikimedia.org/wiki/File:Cryptococcosis_of_lung_in_patient_with_AIDS._Mucicarmine_stain_962_lores.jpg Micrograph of crytococcosis - mucicarmine stain (WC)].
*[http://commons.wikimedia.org/wiki/File:Cryptococcosis_of_lung_in_patient_with_AIDS_Methenamine_silver_stain_963_lores.jpg Micrograph of crytococcosis - methenamine silver stain (WC)].
 
Notes:
*May be confused with corpora amylacea in the CNS, esp. as they (like cryptococci) stain for methenamine silver, Alcian blue, and PAS.<ref>URL: [http://flylib.com/books/en/2.953.1.17/1/ http://flylib.com/books/en/2.953.1.17/1/]. Accessed on: 15 December 2010.</ref>
 
==Cryptosporidiosis==
===General===
*Caused by cryptosporidium.
*Fecal-oral transmission.
*Usu. in immunoincompetent individuals, e.g. [[HIV|HIV/AIDS]].
 
===Microscopic===
Features:
*Uniform spherical nodules 2-4 micrometres in diameter, typical location - GI tract brush border.
**Bluish staining of brush border '''key feature''' - low power.
 
Images:
*[http://www.co.hennepin.mn.us/portal/site/HCInternet/menuitem.3f94db53874f9b6f68ce1e10b1466498/?vgnextoid=bab360a6bb9fc010VgnVCM1000000f094689RCRD Micrograph of cryptosporidium in the gallbladder (hennepin.mn.us)].
*[http://www.tulane.edu/~wiser/protozoology/notes/images/cp_path.gif Schematic picture of cryptosporidium & bowel (tulane.edu)].
*[http://www.brown.edu/Courses/Digital_Path/systemic_path/GI/cryptosporidiosis.html Micrograph of cryptosporidiosis (brown.edu)].
*[http://www.sciencephoto.com/images/download_lo_res.html?id=670052525 Cryptosporidium - colon (sciencephoto.com)].
 
Notes:
*Cryptosporidium parvum?<ref>[http://www.dpd.cdc.gov/dpdx/HTML/Cryptosporidiosis.htm http://www.dpd.cdc.gov/dpdx/HTML/Cryptosporidiosis.htm]</ref>
 
==Candidiasis==
*Commonly ''Candida albicans'' - yeast (fungus), locations: oral cavity, vagina.
*''Dimorphic'' - seen in two forms:
**Pseudohyphae<ref name=Ref_WMSP3>{{Ref WMSP|3}}</ref>  - collections of many ''C. albicans'' cells in a branching pattern.
**Yeast form - single cells, 10 to 12 micrometres in diameter, gram positive.<ref>[http://pathmicro.med.sc.edu/mycology/mycology-3.htm http://pathmicro.med.sc.edu/mycology/mycology-3.htm]</ref>
*Stains: PAS, methenamine silver.
*Images:
**[http://pathmicro.med.sc.edu/mycology/candi4.jpg Candida (pseudohyphae) - methenamine silver (med.sc.edu)].
**[http://commons.wikimedia.org/wiki/File:Candida_pap_1.jpg Candida on Pap test (WC)].
 
==Blastomycosis==
*Usually ''Blastomyces dermatitidis'' - fungus.
*May be in the oral cavity.<ref name=Ref_WMSP3>{{Ref WMSP|3}}</ref>
*Histology = '''B'''road-based budding yeast -- is '''B'''lastomyces.<ref name=pmid12375640>PMID 12375640</ref>
**The interface between two separating fungi, i.e. fungi in the process of reproducing, is very large.
*Images:
**[http://commons.wikimedia.org/wiki/File:Blastomycosis_cropped.JPG Blastomycosis (wikimedia.org)].
**[http://www.pathguy.com/lectures/blastomycosis.jpg Blastomycosis - budding (pathguy.com)].
**[http://www.lahey.org/Medical/InfectiousDiseases/ID_Blastomycosis.asp Blastomycosis - with broad budding (lahey.org)].
 
 
==Mucormycosis==
===General===
*Causative organism: Mucorales.
**Kingdom: Fungi.
**AKA ''Zygomycota'' (zygomycosis).
*Assoc. with diabetes, immunodeficiency.
 
===Histology===
Features:<ref name=Ref_APBR682>{{Ref APBR|682}}</ref>
*Branching hyphae variable width.
*Granulomata associated.
 
Image:
*[http://commons.wikimedia.org/wiki/File:Zygomycosis.jpg Zygomycosis - cytology (WC)].
*[http://granuloma.homestead.com/ZygoHE_02.jpg Mucormycosis (homestead.com)].


==Worms & stuff==
==Worms & stuff==

Revision as of 04:09, 15 November 2011

Microorganisms show-up every once in a while. It is essential to know 'em.

Microorganisms

Name (disease) Kingdom Size Shape Stains Other (microscopic) Clinical References Image
Aspergillus (aspergillosis) Fungi ? Hyphae that branching
with 45 degrees angle 		PAS-D Fruiting heads when aerobic ? Immunosuppression [1] Aspergillus (WC), Aspergillus cytology (WC)
Zygomycota (zygomycosis);
more specific
Mucorales (mucormycosis) 		Fungi ? Branching hyphae with variable width ? Granulomata assoc. Diabetes, immunodeficient [1] Mucormycosis (homestead.com), Zygomycosis (WC)
Coccidioides, usually C. immitis
(coccidioidomycosis) 		Fungi Large - 20-60 micrometers,
endospores 1-5 micrometers 		Spherules Stains? Other? Immunodeficient [1] Coccidioidomycosis (med.sc.edu) C. immitis (WC) (webpathology.com)
Histoplasma (histoplasmosis) Fungi 2-5 micrometers Spherical GMS Intracellular (unlike candida), granulomata Source: soil with bird droppings [1] Histoplasmosis (WC)
Blastomyces (Blastomycosis) Fungi 5-15 micrometres Spherical (yeast) Stains? Granulomas, broad-based budding yeast Habitat: Northeast America, Africa [1][2] Blastomyces
Paracoccidioides (Paracoccidioidomycosis) Fungi 6-60 micrometres Spherical (yeast) Stains? Multiple budding "steering wheel" appearance Clinical??? [1] P. brasiliensis (WC).
Pneumocystis jirovecii (Pneumocystis carinii pneumonia; abbrev. PCP) Fungi (previously thought to be a protozoan) 7-8 micrometres "Dented ping-pong ball" GMS Usually in clusters of alveolar casts with a honeycomb appearance HIV/AIDS associated [3] PCP (WC)
Cryptococcosis Fungi 5-15 micrometres Yeast GMS Prominent (i.e. thick polysaccharide) capsule HIV/AIDS associated, most common CNS fungus [1] Crytococcosis - methenamine silver (WC), Crytococcosis - mucicarmine (WC).

Notes:

  • Bold text = key features.

Fungi

Main article: Fungi
  • There are lots of 'em. Below are a few of 'em.

Terminology:[4]

  • Hyphae = microscopic filamentous growth (of fungi) -- single cell.
  • Mycelial = filamentous network of hyphae.
  • Septae/septation = hyphae may be subdivided by septae -- if they aren't they are one mass of protoplasm. (?)
  • Dimorphism = exist in two forms; e.g. single cell (yeast) and mycelial growth.
  • Pseudohyphae = looks like hyphae --but branching pattern is created by separate cells.[5]

Tissue invasive fungi

Typically:[6]

  • Mucor.
  • Aspergillus.

List

Histoplasmosis Coccidioidmycosis Pneumocystis pneumonia Cryptococcus Cryptosporidiosis Candidiasis Blastomycosis Mucormycosis

Worms & stuff

Schistosoma

See Urine cytopathology.
  • Associated with squamous cell carcinoma of the bladder.

Microscopic

Features of ova:

  • Elliptical ~80 micrometres max dimension.
  • S. haematobium has a "spike" approx. the size of a PMN.

Image:

Toxoplasma

General

  • Common CNS infection.
    • Toxoplasma gondii - pathogenic; causes toxoplasmosis.
  • Protozoa.

Microscopic

General:

  • Dependent on location in body.

Lymph node

LN features:[7]

  • Reactive germinal centers (pale areas - larger than usual).
    • Often poorly demarcated - due to loose epithelioid cell clusters at germinal center edge - key feature.
  • Epithelioid cells - perifollicular & intrafollicular.
    • Loose aggregates of histiocytes (do not form round granulomas):
      • Abundant pale cytoplasm.
      • Nucleoli.
  • Monocytoid cells (monocyte-like cells) - in cortex & paracortex.
    • Large cells in islands/sheets key feature with:
      • Abundant pale cytoplasm - important.
      • Well-defined cell border - important.
      • Singular nucleus.
    • Cell clusters usually have interspersed neutrophils.

Images (lymph node):

CNS

CNS features:[8]

  • Granular appearing ball ~ 2x the size of resting lymphocyte.

Images (CNS):

IHC

  • IHC for toxoplasma.[9]

Strongyloidiasis

General

  • Causes by worm Strongyloides stercoralis.
  • High case mortality rate ~ 70%.[10]
  • May present after years of latency due to immune suppression.[11]

Location:

  • Lung. (???)

Microscopic

Features:

  • Long worms.
  • ~10-15 micrometers wide.

Images:

Echinococcus

Microscopic

Features:

  • Laminated wall +/- calcification.[12]
  • Organisms:
    • Hooklets.
    • Scoleces - knoblike anterior end of a tapeworm.[13]

Enterobius vermicularis

  • AKA pinworm.

Features:[14]

  • Ovoid eggs - double walled shells, one side flat.

Images:

Trichinella

General

  • Causes Trichinosis.
    • Classically associated with uncooked pork.[15]
  • Several types; most due to T. spiralis.[15]

Microscopic

Features:

  • Worm.

Image:

Cysticercosis

General

  • Caused by Taenia solium; pork tapeworm.
  • May cause epilepsy; most common parasitic CNS infection.[17]

Viruses

Main article: Viruses

This is a fairly big topic. There are about half a dozen viral inclusions (e.g. CMV, HSV, VZV, adenovirus) a decent pathologist ought to be able to identify. The virus article covers 'em.

Bacteria

Main article: Bacteria

This is a small topic when considered from the perspective of an anatomical pathologist. Most stuff is sorted-out by microbiology.

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Lefkowitch, Jay H. (2006). Anatomic Pathology Board Review (1st ed.). Saunders. pp. 682. ISBN 978-1416025887.
  2. ↑ http://pathmicro.med.sc.edu/mycology/mycology-6.htm
  3. ↑ Lefkowitch, Jay H. (2006). Anatomic Pathology Board Review (1st ed.). Saunders. pp. 684. ISBN 978-1416025887.
  4. ↑ http://www.fungionline.org.uk/1intro/3growth_forms.html
  5. ↑ http://pathmicro.med.sc.edu/mycology/mycology-3.htm
  6. ↑ CM 17 Apr 2009.
  7. ↑ Ioachim, Harry L; Medeiros, L. Jeffrey (2008). Ioachim's Lymph Node Pathology (4th ed.). Lippincott Williams & Wilkins. pp. 113. ISBN 978-0781775960.
  8. ↑ URL: http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/N0I001-PQ01-M.htm. Accessed on: 19 October 2010.
  9. ↑ URL: http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/N0I001-PQ01-M.htm. Accessed on: 19 October 2010.
  10. ↑ Lim, S.; Katz, K.; Krajden, S.; Fuksa, M.; Keystone, JS.; Kain, KC. (Aug 2004). "Complicated and fatal Strongyloides infection in Canadians: risk factors, diagnosis and management.". CMAJ 171 (5): 479-84. doi:10.1503/cmaj.1031698. PMID 15337730.
  11. ↑ Siddiqui, AA.; Berk, SL. (Oct 2001). "Diagnosis of Strongyloides stercoralis infection.". Clin Infect Dis 33 (7): 1040-7. doi:10.1086/322707. PMID 11528578.
  12. ↑ Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 448. ISBN 978-1416054542.
  13. ↑ http://www.thefreedictionary.com/scoleces. Accessed on: 10 January 2010.
  14. ↑ Lefkowitch, Jay H. (2006). Anatomic Pathology Board Review (1st ed.). Saunders. pp. 685. ISBN 978-1416025887.
  15. ↑ 15.0 15.1 Kaewpitoon N, Kaewpitoon SJ, Philasri C, et al. (October 2006). "Trichinosis: epidemiology in Thailand". World J. Gastroenterol. 12 (40): 6440–5. PMID 17072975. http://www.wjgnet.com/1007-9327/12/6440.asp.
  16. ↑ URL: http://library.med.utah.edu/WebPath/EXAM/IMGQUIZ/msfrm.html. Accessed on: 5 December 2010.
  17. ↑ Prasad KN, Prasad A, Verma A, Singh AK (November 2008). "Human cysticercosis and Indian scenario: a review". J. Biosci. 33 (4): 571–82. PMID 19208982.
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