What is the differential diagnosis, workup, and management for calcific (crystal) deposits in the folds of the external ear (auricular cartilage)?

Calcific Deposits in the External Ear

Crystal deposits in the ear folds are most commonly due to calcium pyrophosphate deposition (CPPD) presenting as chondrocalcinosis, though other calcific conditions and systemic diseases must be excluded through targeted workup.

Differential Diagnosis

The primary considerations for auricular cartilage calcification include:

• Calcium pyrophosphate deposition disease (CPPD) - the most common cause of cartilage calcification, particularly in older adults 1
• Basic calcium phosphate (BCP) crystal deposition - including hydroxyapatite crystals 1
• Monosodium urate crystals (gout) - though typically presents with tophi rather than diffuse cartilage calcification 1
• Secondary causes requiring exclusion:
  • Hyperparathyroidism 1, 2
  • Hemochromatosis 1, 2
  • Hypomagnesemia 1, 2
  • Hypophosphatasia 2
  • Hypothyroidism 2
  • Acromegaly 3
• Local factors: Prior frostbite, trauma, or chronic inflammation 3

Diagnostic Workup

Imaging Assessment

Initial imaging should be conventional radiography to identify chondrocalcinosis and assess distribution 1:

• Radiography has 100% specificity for detecting cartilage calcification 1
• Look for calcification in auricular cartilage, knee menisci, wrist triangular fibrocartilage, and symphysis pubis 4, 5

Advanced imaging considerations:

• Ultrasound can detect early cartilage changes before radiographic calcification appears 1, 5
• CT is more sensitive than radiography for detecting subtle calcifications 1
• Dual-energy CT can specifically identify monosodium urate crystals if gout is suspected 1

Laboratory Evaluation

Screen for metabolic and endocrine disorders, particularly in patients under 60 years 6, 2:

• Serum calcium and parathyroid hormone (hyperparathyroidism) 1, 2
• Serum magnesium (hypomagnesemia) 1, 2
• Iron studies including ferritin and transferrin saturation (hemochromatosis) 1, 2
• Alkaline phosphatase (hypophosphatasia) 2
• Thyroid function tests (hypothyroidism) 2
• Consider IGF-1 if acromegaly features present 3

Crystal identification if joint symptoms present:

• Arthrocentesis with polarized light microscopy to identify specific crystal type 5
• This distinguishes CPPD (rhomboid, weakly positive birefringent) from urate crystals (needle-shaped, strongly negative birefringent) 5

Management

Asymptomatic Chondrocalcinosis

No treatment is required for isolated, asymptomatic cartilage calcification 1:

• This represents an incidental age-related finding in most cases 1, 4
• Prevalence increases dramatically over age 70 1

If Symptomatic (Acute or Chronic Arthritis)

For acute CPP crystal arthritis, first-line treatment combines non-pharmacological and local measures 1:

• Cool packs and temporary rest 1
• Joint aspiration with intra-articular corticosteroid injection for affected joints 1
• This approach alone is sufficient for many patients (95% strength of recommendation) 1

Systemic pharmacological options for acute attacks 1:

• Oral NSAIDs with gastroprotection (if no contraindications) 1
• Low-dose colchicine 0.5 mg up to 3-4 times daily 1
• Both have 79% strength of recommendation but are limited by toxicity in elderly patients 1

Alternative systemic therapy when NSAIDs/colchicine contraindicated 1:

• Short tapering course of oral corticosteroids 1
• Parenteral corticosteroids or ACTH 1
• 87% strength of recommendation 1

For chronic CPP crystal inflammatory arthritis, pharmacological hierarchy 1:

1. Oral NSAIDs (with gastroprotection) and/or colchicine 0.5-1.0 mg daily 1
2. Low-dose corticosteroids 1
3. Methotrexate 1
4. Hydroxychloroquine 1

Treatment of Underlying Metabolic Disorders

If associated metabolic conditions are identified, treat the underlying disease 1:

• This has 89% strength of recommendation 1
• However, no current treatment modifies CPP crystal formation or dissolution 1

Key Clinical Pitfalls

• Age matters: Chondrocalcinosis in patients under 60 years warrants aggressive metabolic workup, as it may indicate underlying systemic disease 6, 2
• Hemochromatosis is unique: It is the only metabolic disorder clearly associated with both chondrocalcinosis AND chronic structural arthropathy, not just acute attacks 2
• Don't confuse with infection: Always exclude septic arthritis through arthrocentesis when acute joint inflammation is present 5
• Multiple crystal types can coexist: Patients may have CPPD at one site and hydroxyapatite or urate crystals at another 4
• Medication toxicity: NSAIDs and colchicine carry significant risks in elderly patients with comorbidities, particularly renal impairment 1