Basic calcium phosphate disease — SCE Rheumatology MCQ

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EasyCrystal arthropathiesBasic calcium phosphate diseaseSCE Rheumatology

A 70-year-old woman develops sudden severe unilateral shoulder pain after a minor pulling strain. She is afebrile and systemically well. Both active and passive shoulder movements are markedly restricted by pain. Plain radiography shows an amorphous calcific deposit within the supraspinatus tendon, with no fracture or glenohumeral erosions. What is the most likely diagnosis?

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Correct answer: D — Basic calcium phosphate calcific tendinopathy

The diagnosis is basic calcium phosphate calcific tendinopathy, also termed calcific periarthritis. The discriminating feature is the amorphous calcific deposit within the supraspinatus tendon, together with acute severe pain and movement restriction. Basic calcium phosphate deposition in rotator cuff tendons can provoke an intense inflammatory episode. Shoulder gout is uncommon and would not characteristically produce this tendon-localised calcification. Septic arthritis must be considered in an acutely painful shoulder, but systemic wellness and a characteristic peri-tendinous deposit favour calcific tendinopathy; suspected infection would still require urgent aspiration. Polymyalgia rheumatica usually causes bilateral shoulder and hip-girdle aching with morning stiffness. A full-thickness cuff tear predominantly impairs active movement and does not itself explain the characteristic calcific deposit.

Reference: National Institute for Health and Care Excellence. HTG645, Extracorporeal shockwave therapy for calcific tendinopathy in the shoulder, section 2.1: The condition. 2022. https://www.nice.org.uk/guidance/HTG645/chapter/2-the-condition-current-treatments-and-procedure