BCP  (Basic Calcium Phosphate) Crystal

  • Two syndromes
    • Calcific Periarthritis (bursa, tendon and other soft tissues)
      • F > M, Age: 28-78
      • Average duration of clinical course: 4.4 months
      • Duration and severity did not correlate with the size of the deposits
      • Sites
        • Shoulder 
        • Hip (Gluteus medius tendon, Reflected Head of Rectus Femoris; Direct head of Rectus femoris, Iliopsoas, Piriformis) 
      • Barbotage and Arhroscopic Surgery may be needed in some
    • BCP Crystal associated Arthritis 
      • Similar to OA 
      • Highly destructive Milwaukee Shoulder Syndrome (MSS)
  • BCP: trio of calcium phosphate crystals consisting of
    •  carbonate substituted hydroxyapatite, 
    • octacalcium phosphate, and
    •  tricalcium phosphate. 
  • Ddx
    • Hypophosphatasia - Alkaline Phosphotase deficiency - has high Phosphrous level, 
    • Deficiency in ENT1 (equilibrative nucleoside transporter-1, SLC29A1) and 
    • the Augustine-null blood type 

Ref: Curr Opin Rheumatol. 2018 March ; 30(2): 168–172. doi:10.1097/BOR.0000000000000477