Joints

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Joints are important for locomotion. This article collects tidbits about their pathology.

Prosthetic joint infection

General

  • Bits of tissue come for frozen section to r/o infection.
  • The interface membrane (not the pseudocapsule) should be sampled to obtain a high sensitivity.[1]

Microscopic

Features:

  • Neutrophils - key feature.

Notes:

  • Various criteria for the number of neutrophils exist (see below).[2]
    • The definitions suffer from HPFitis.
  • Finding of plasma cells and lymphocytes is not contributory for the diagnosis of infection.[2]
  • Granulomatous inflammation that isn't of a foreign-body type should get the usual work-up.[3]

Feldman criteria

  • >= Five neutrophils / HPF (x400) in at least five separate microscopic fields.[2][1]

Athanasou criterion

  • >= Ten neutrophils / ten HPF (x400).[2]

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HEMATOMA, RIGHT HIP, IRRIGATION AFTER HIP REPLACEMENT/TISSUE REMOVAL:
- FIBROADIPOSE TISSUE WITH POSTSURGICAL CHANGES INCLUDING:
-- FOREIGN-BODY TYPE MULTINUCLEATED GIANT CELLS AND FOREIGN MATERIAL.
-- GRANULATION TISSUE.
-- FAT NECROSIS (FOCAL).
- FIBRIN, BLOOD.
- NEUTROPHILS IN BLOOD VESSEL WALLS/PERIVASCULAR (FOCAL), SEE COMMENT.
- NEGATIVE FOR MICROORGANISMS WITH ROUTINE STAIN.

COMMENT:
Up to 17 neutrophils per high power field (0.55 mm field diameter) are seen.
FEMUR, LEFT, BIOPSY:
- BONE MARROW WITH PATCHY MILD FOCAL PROMINENCE OF PLASMA CELLS AND NEUTROPHILS.
- FIBROUS TISSUE WITH HEMOSIDERIN, ISOLATED NEUTROPHILS AND RARE
MACROPHAGES.
- BONE FRAGMENTS.
- NEGATIVE FOR MICROABSCESS FORMATION.
- NEGATIVE FOR MICROORGANISMS WITH ROUTINE STAINS.

Juxta-articular myxoma

  • Abbreviated JAM.

General

  • Classically present as a mass or with pain.[4]
  • May recur.
  • Described as (microscopically) indistinguishable from intramuscular myxoma.[5]

Gross

Features:

  • Close to large joints - classically around the knee.
    • >85% of cases around the knee in one large series.[4]

Microscopic

Features:[4]

  • Myxomatous stroma.
  • +/-Cystic changes.
  • Large nuclei with hyperchromasia and nuclear scalloping.[6]

DDx:

Images:

Morton neuroma

Ganglion cyst

General

  • Very common.
    • Most common tumour of the hand.[7]
  • Classically on the wrist.[8]
  • May be painful.[9]

Gross

  • Mass at a joint - classically in the hand.

DDx - clinical:

Microscopic

Features:[7][9]

  • Empty space(s); usually multiple.
  • Fibrotic wall.
  • No epithelial lining.†
  • +/-Myxoid change - very common.
    • May have some spindled fibroblasts.


† The entity is really a pseudocyst.[7]

DDx:

Images:

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SOFT TISSUE ("GANGLION CYST"), LEFT WRIST, EXCISION:
- GANGLION CYST.

Micro

The sections show fibroadipose tissue with cyst-like spaces surrounded by fibrous tissue. There are no villous projections into the cyst-like spaces. Focal myxoid areas are present with rare bland spindle cells. There is no nuclear atypia and no mitotic activity is appreciated. Dense connective tissue consistent with tendon is present focally.

Rheumatoid arthritis

See also

References

  1. 1.0 1.1 Bori, G.; Muñoz-Mahamud, E.; Garcia, S.; Mallofre, C.; Gallart, X.; Bosch, J.; Garcia, E.; Riba, J. et al. (Apr 2011). "Interface membrane is the best sample for histological study to diagnose prosthetic joint infection.". Mod Pathol 24 (4): 579-84. doi:10.1038/modpathol.2010.219. PMID 21131917.
  2. 2.0 2.1 2.2 2.3 Bori, G.; Soriano, A.; García, S.; Mallofré, C.; Riba, J.; Mensa, J. (Jun 2007). "Usefulness of histological analysis for predicting the presence of microorganisms at the time of reimplantation after hip resection arthroplasty for the treatment of infection.". J Bone Joint Surg Am 89 (6): 1232-7. doi:10.2106/JBJS.F.00741. PMID 17545426.
  3. URL: http://path.upmc.edu/cases/case174.html. Accessed on: 8 January 2012.
  4. 4.0 4.1 4.2 Meis, JM.; Enzinger, FM. (Jun 1992). "Juxta-articular myxoma: a clinical and pathologic study of 65 cases.". Hum Pathol 23 (6): 639-46. PMID 1592386.
  5. Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 624. ISBN 978-0781765275.
  6. URL: http://path.upmc.edu/cases/case38/micro.html. Accessed on: 2 January 2011.
  7. 7.0 7.1 7.2 URL: http://emedicine.medscape.com/article/1253223-overview]. Accessed on: 8 February 2012. Cite error: Invalid <ref> tag; name "emed_gc" defined multiple times with different content
  8. Hasham, S.; Burke, FD. (May 2007). "Diagnosis and treatment of swellings in the hand.". Postgrad Med J 83 (979): 296-300. doi:10.1136/pgmj.2005.043992. PMID 17488856.
  9. 9.0 9.1 9.2 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 322. ISBN 978-0443066542.
  10. Cuono, CB.; Watson, HK. (Jan 1979). "The carpal boss: surgical treatment and etiological considerations.". Plast Reconstr Surg 63 (1): 88-93. PMID 432327.