IS Case 375: Dense metaphyses, unknown etiology
2009 URMC Imaging Sciences
Publication Date: 2010-03-02
History
Patient is a 3-year-old male referred for evaluation of leg alignment. Patient was born at 36 weeks gestation and has a history of gross motor delays and foot pronation with outward gait.
Findings
Bilateral dense metaphyses. Normal alignment. Both femurs measure 21 cm from the greater trochanter to the distal and mid aspect of the epiphysis. Both tibia measure 18 cm.
Diagnosis
Dense metaphyses, unknown etiology
Discussion
Dense metaphyses refer to increased density at the growing ends of long bones, especially wrists and knees. The most common cause of dense metaphyses is a normal variant. It can be seen after long winter months when children are exposed to sunlight. Another cause is lead poisoning. These "lead lines" indicate past exposure to lead. When lead levels decrease, these lines will decrease and eventually disappear within 4 years. Other less common etiologies include: treated leukemia, healing rickets, heavy metal poisoning (arsenic, bismuth, mercury), recovery from scurvy, vitamin D hypervitaminosis, congenital hypothyroidism, hypoparathyroidism and transplacental infection (toxoplasmosis, rubella, CMV and herpes). It is likely due to an accelerated repair phase of bone after a metabolic insult. In heavy metal poisoning, the metal salt is absorbed into the the bone matrix in place of calcium.
References
- Raber SA. The dense metaphyseal band sign. Radiology. 1999 Jun;211(3):773-4. PMID: 10352605
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