Tumoral Calcinosis - Pathology

Introduction
Rare and poorly understood hereditary metabolic dysfunction of phosphate regulation associated with massive periarticular calcinosis in the extra-capsular soft tissues Epidemiology demographics more common in females and African-Americans onset in childhood or early adolescence location around joints, primarily the hip (trochanteric bursa is most common location) > shoulder Pathophysiology unknown inborn abnormality of phosphorus metabolism FGF-23 defect leading to familial hyperphosphatemic tumoral calcinosis

Presentation

Symptoms
- mass or swelling typically around joints
- pain secondary to compression of normal surrounding structures
Physical exam
- inspection
  - palpable mass around joint

Imaging

Radiographs
- amorphous, cystic, lobular (circular or oval) well-demarcated calcification in periarticular location
- direct involvement of the bones or joints is rare
CT
- findings
  - may demonstrate fluid-fluid levels within some of these masses
    - calcium layering ("sedimentation sign")
  - or may have homogenous appearance
    - reduced metabolic activity, lower likelihood of growth
MRI
- findings
  - diffuse, low signal intensity
  - bright, nodular pattern with alternating areas of high signal intensity and signal void
  - may demonstrate fluid-fluid levels (as with CT)
Bone scan
- radionuclide bone scan may reveal intense uptake in the calcific masses

Studies

Labs
- normal or slightly elevated renal and parathyroid function
- normal or slightly elevated serum calcium, phosphorus, uric acid, and alkaline phosphatase
Histology
- lobulated soft tissue masses with well-defined capsules and thick septae
- masses are filled with calcareous material (calcium phosphate, calcium carbonate and calcium hydroxyapatite) and fluid

Differentials

Calcinosis of renal failure (secondary tumoral calcinosis)
- approximately 1% prevalence of periarticular masses
- may occur independent of concomitant hyperparathyroidism
- no radiologic/histologic differences with primary tumoral calcinosis
  - diagnosis is based on vitamin D levels, GFR, hyperphosphatemia, and history of chronic renal failure/long term dialysis
Calcific tendinitis
- shoulder > hip > elbow > wrist > knee
- occurs within tendon
- no sedimentation of calcium (makes it different from tumoral calcinosis)
Synovial osteochondromatosis
- occurs within joint/tendon sheath
- "rings and arcs" and intra-articular location (makes it different from tumoral calcinosis)
Myositis ossificans and heterotopic ossification
- not lobular
- evolves rapidly from faint calcification to organized cartilage and bone in 6 weeks
- late lesions of HO have well developed cortex and medullary cavity
Gout
- may have hyperuricemia
- focal erosions of underlying bone

Treatment

Nonoperative
- observation
  - indications
    - treatment of choice for non-symptomatic lesions
Operative
- complete surgical excision
  - indications
    - treatment of choice for symptomatic lesions
  - technique
    - complete surgical excision is required to decrease the rate of local recurrence
  - results
    - risk of recurrence
      - if lesion is poorly circumscribed
      - if excision is performed while lesion is actively growing

Complications