Diagnosis of Soft Tissue Calcification

Familiarity with the appearance of extraskeletal soft tissue calcification on different scintigraphic modalities is crucial since unexpected soft tissue uptake on these modalities is often a source of uncertainty and doubt to inexperienced physicians, which may lead to inappropriate diagnosis. There are three major types of extraosseous calcification: dystrophic, metastatic, and heterotopic. Dystrophic calcification involves the deposition of calcium in damaged tissue and is not usually associated with hypercalcemia. In metastatic calcification, calcium deposition occurs in normal tissue due to hypercalcemia and/or hyperphosphatemia due to a variety of disease conditions, particularly metabolic disorders following renal failure. Heterotopic ossification describes a unique condition that may, or may not, follow trauma and is due to a complex pathogenetic mechanism believed to be due to the transformation of certain primitive cells of mesenchymal origin in the connective tissue septa within muscles into bone-forming cells. Bone scanning can detect all types of soft tissue calcification, usually serendipitously, in cases of dystrophic and metastatic calcification. In the case of heterotopic ossification, bone scanning has a more defined role in early diagnosis of the condition, in follow-up, and in determining the proper timing of surgical intervention. Cardiac calcinosis, which is one of the rare findings of metastatic calcification, can be fatal, and bone scanning can be a sensitive noninvasive method for its detection, in addition to the occasional discovery as an incidental finding on a bone scan performed for other reasons. Calcification of the skin, or calcinosis cutis, can occasionally be seen on bone scans, and familiarity with the findings and the patterns of other types of calcifications helps enrich the diagnostic value of the bone scintigraphy. Scintigraphy is useful in evaluating the degree of muscle necrosis of rhabdomyolysis. Familiarity with the appearance of extraskeletal soft tissue calcification on different scintigraphic modalities is crucial since unexpected soft tissue uptake on these modalities is often a source of uncertainty and doubt to inexperienced physicians, which may lead to inappropriate diagnosis. There are three major types of extraosseous calcification: dystrophic, metastatic, and heterotopic (Choi and Lee Atlas of nuclear medicine in musculoskeletal system. Springer, Singapore, 2022). Dystrophic calcification involves the deposition of calcium in damaged tissue and is not usually associated with hypercalcemia. In metastatic calcification, calcium deposition occurs in normal tissue due to hypercalcemia and/or hyperphosphatemia due to a variety of disease conditions, particularly metabolic disorders following renal failure. Heterotopic ossification describes a unique condition that may, or may not, follow trauma and is due to a complex pathogenetic mechanism believed to be due to the transformation of certain primitive cells of mesenchymal origin in the connective tissue septa within muscles into bone-forming cells. Bone scanning can detect all types of soft tissue calcification, usually serendipitously, in cases of dystrophic and metastatic calcification. In the case of heterotopic ossification, bone scanning has a more defined role in early diagnosis of the condition, in follow-up, and in determining the proper timing of surgical intervention. Cardiac calcinosis, which is one of the rare findings of metastatic calcification, can be fatal, and bone scanning can be a sensitive noninvasive method for its detection, in addition to the occasional discovery as an incidental finding on a bone scan performed for other reasons. Calcification of the skin, or calcinosis cutis, can occasionally be seen on bone scans, and familiarity with the findings and the patterns of other types of calcifications helps enrich the diagnostic value of the bone scintigraphy. Scintigraphy is useful in evaluating the degree of muscle necrosis of rhabdomyolysis.