Tumoral calcinosis occurs when a large amount calcium salts deposit into the soft tissues. The calcium deposition is considered heterotopic, but it is neither ossification nor osteoid matrix formation. The calcifications are separate from bone.

Large amounts of periarticular calcinosis may occur as a result of:

• renal failure
• secondary hyperparathyroidism

or it may be idiopathic in younger people, as in this case. Technically, only the idiopathic form is known as "tumoral calcinosis".

A differential diagnosis includes:

• hydroxyapatite deposition disease (HADD)
  • may appear similar, but is limited to a small focus in a tendon or a bursa
• bone forming tumor with osteoid matrix (e.g. parosteal osteosarcoma)
• a wide variety of soft tissue masses with calcification, both benign and malignant

In this case, the patient age, the normal renal and thyroid function, and the bilateral findings, point toward idiopathic "tumoral calcinosis".