• Metastatic: the result of abnormal calcium metabolism • Calcinosis: occurring with a normal calcium metabolism • Dystrophic: related to tissue damage • Ossification: bony trabeculae are discernible (either ectopic or heterotropic) • The differential diagnosis is divided into: • Localized intratumoral calcification may occur within any soft tissue tumour due to haemorrhage or necrosis • Benign mineralizing tumours: soft tissue chondroma (punctuate or ‘ring and arc’ calcification) • Malignant mineralizing tumours: extraskeletal osteosarcoma • Developmental causes include fibrodysplasia ossificans progressiva, melorheostosis and progressive osseous heteroplasia • Post-surgical: this particularly occurs following a total hip arthroplasty (± pain and restricted movement) • Haemorrhage is followed by mineralization • Early biopsy should be avoided (as it can resemble a soft tissue osteosarcoma) • It is associated with burns and paraplegia This results from prolonged elevation of the serum calcium (or more importantly serum phosphate) • Primary hyperparathyroidism: calcification is typically seen involving arteries, cartilage (chondrocalcinosis) and periarticular tissues • Secondary hyperparathyroidism: soft tissue and vascular calcification is more common than in primary disease • Hypoparathyroidism: subcutaneous and basal ganglia calcification • Pseudohypoparathyroidism: there are similar features to hypoparathyroidism but it is associated with growth deformities (broad bones, cone epiphyses, short metacarpals and metatarsals – especially the 1st, 4th and 5th) • Pseudopseudohypoparathyroidism: XR features are identical to pseudohypoparathyrodism (but with a normal serum calcium and phosphate) • Hypervitaminosis D: smooth lobulated amorphous calcium hydroxyapatite masses within the periarticular regions, bursae, tendon sheaths and the joint capsule • Mönckeberg’s arteriosclerosis: finer ‘pipe-stem’ calcification seen with medial degeneration • Diabetes: calcification of the small vessels of the feet • Renal failure/hyperparathyroidism: a fine more generalized pattern of arterial calcification • Aneurysms: rounded, curvilinear and crescentic calcification
Soft tissue imaging
LOCALIZED CALCIFICATION AND OSSIFICATION
LOCALIZED CALCIFICATION AND OSSIFICATION
Definition
calcium deposits tend to be more densely sclerotic than in normal bone
LOCALIZED CALCIFICATION – TUMOURS
Definition
lipoma (ossification can occur, especially if it is parosteal)
haemangiomas (phleboliths)
extraskeletal chondrosarcoma
synovial sarcoma (with a central rather than peripheral distribution)
HETEROTOPIC OSSIFICATION
Definition
Pellegrini–Stieda lesion: ossification of the medial collateral knee ligament
Neurogenic heterotropic ossification: soft tissue ossification associated with CNS injuries (with prolonged unconsciousness and spinal trauma)
there is a periarticular distribution (commonly affecting the hips)
surgery is associated with recurrence
Avulsion of an ossification centre: in the skeletally immature an avulsed ossification centre may continue to grow
this may present later as a large ossified soft tissue mass (commonly affecting the pelvic and hamstring pelvic origins)
MYOSITIS OSSIFICANS
Definition
this is first seen in the periphery with a gradual reduction in the size of the mass (which are both helpful in distinguishing from a mineralizing soft tissue sarcoma)
it is commonly seen around the elbow and in the thigh
GENERALIZED SOFT TISSUE CALCIFICATION
METABOLIC DISORDERS
Definition
chondrocalcinosis is infrequent
osteosclerosis
premature epiphyseal closure
band-like paraspinal calcification (mimicking DISH)
dense metaphyseal bands and cortical thickening (± osteosclerosis in children)
osteoporosis in adults
ARTERIAL CALCIFICATION
Definition