Sunday, July 9, 2017

Hemochromatosis: Hand Manifestations


50-year-old man with subtle manifestations of hemochromatosis arthropathy. Note narrowing of the metacarpophalangeal (MCP) joints, more advanced at the index and middle fingers. Other features of hemochromatosis arthropathy are not present, specifically, there is no subchondral cyst formation, hook-like osteophytes, osteoporosis, or chondrocalcinosis and the radiocarpal articulation is unaffected.

Hemochromatosis: General
  • Autosomal recessive disorder
  • Several genes implicated
  • Body has mechanism for dealing with low Fe (increased intestinal absorption), but no effective way of dealing with excess Fe
  • Fe accumulates in organs
  • Damage via Fe2+ -> Fe3+ -> Oxidation -> Free radicals


Arthropathy
  • Present in 50% of patients when rigorous criteria are used to define arthritis
  • Males affected earlier and more severely
  • Associated with use of joint
  • Typically a chronic process
  • Acute episodes of inflammatory arthritis may occur: May be associated with recovery of CPPD crystals from joint fluid aspiration.
  • Rare syndrome of septicemia accompanied by monoarticular or oligoarticular septic arthritis caused by Yersinia species described: Prosthetic joints seem especially susceptible to this infection.


Pathophysiology
  • Hemosiderin found in superficial synovial lining cells and macrophages (phagocytosis of iron loaded synoviocytes)
  • Very little iron detected in deeper synovial layers, and only occasionally in macrophages.
  • Arthropathy generally non-inflammatory. Chronic inflammatory cell infiltrate rarely seen.
  • Minimal to no iron deposition in cartilage.
  • Chondrocalcinosis a frequent finding
  • No close spatial relationship between iron and CPPD crystals, and crystals can be found even in the absence of iron deposits.


Imaging Features
  • Overlap with those of idiopathic OA and CPPD
  • Joint space narrowing
  • Subchondral sclerosis
  • Subchondral cysts
  • Osteophyte formation (hook-like osteophytes can be seen)
  • Chondrocalcinosis in articular and non-articular cartilage
  • Osteoporosis


The deal with chondrocalcinosis
  • Fe2+ (but not Fe3+) inhibits pyrophosphatase
  • Leads to diminished hydrolyzation of inorganic pyrophosphate
  • Contributes to precipitation of inorganic pyrophosphate with calcium.

References

  • Dallos T, Sahinbegovic E, Aigner E, Axmann R, Schöniger-Hekele M, Karonitsch T, Stamm T, Farkas M, Karger T, Cavallaro A, Stölzel U, Keysser G, Datz C, Schett G, Manger B, Zwerina J. Validation of a radiographic scoring system for haemochromatosis arthropathy. Ann Rheum Dis. 2010 Dec;69(12):2145-51.
  • Frenzen K, Schäfer C, Keyßer G. Asymmetrical hemochromatosis arthropathy in a patient with a history of poliomyelitis. Rheumatol Int. 2012 Apr;32(4):1045-7.
  • van Vulpen LF, Roosendaal G, van Asbeck BS, Mastbergen SC, Lafeber FP, Schutgens RE. The detrimental effects of iron on the joint: a comparison between haemochromatosis and haemophilia. J Clin Pathol. 2015 Aug;68(8):592-600.

Sunday, July 2, 2017

Chordoma Drop Metastases



Chordoma drop metastases are extremely rare, with ~11 reported cases. Of these, 1 was present at the time of initial presentation and 3 were only seen at autopsy. The naturally slow growth of chordomas, lack of symptoms in several cases, and late age of onset may mask true incidence of intradural drop metastases.

The imaging features are nonspecific and tend to mirror those of the primary neoplasm.

References

Martin MP, Olson S. Intradural drop metastasis of a clival chordoma. J Clin Neurosci. 2009 Aug;16(8):1105-7.