Benign spotted bones: a diagnostic dilemma

Most reported cases of osteopoikilosis are identified during the investigation of unrelated problems in which there is no clinical history suggestive of either malignant or systemic disease.8,9 In such situations, no further workup is necessary. The characteristic radiologic feature is multiple, punctate, sclerotic, round or oval foci symmetrically distributed in a predominantly periarticular fashion within the epiphyseal and metaphyseal regions.8,9 In the three patients described in this issue, most of the sclerotic foci are 1-2 mm, although some lesions measure up to 10 mm. Although further investigation is unnecessary in typical osteopoikilosis, when radionuclide bone scans are performed, their results are negative. In clinical and radiologic follow-up of osteopoikilosis, the lesions remain stable. As mentioned previously, the characteristic radiologic feature in osteopoikilosis is multiple, punctate, sclerotic, rounded or oval foci. In benign enostosis, or bone islands, which also have sclerotic rounded lesions, the peripheral margins tend to blend or merge with the underlying normal trabecula (Figure 2). These lesions are typically small (< 1 cm) and frequently isolated. Although the lesions in enostosis are usually round or oval, their shape is not specific. If the lesions are larger than 1 cm, other sclerotic bone conditions or lesions must be considered, despite the characteristic appearance of the peripheral margins. If sclerotic lesions are large or numerous, the diagnosis of osteopoikilosis or enostosis is questionable. In addition, bone islands should be blandly homogeneous, as they represent a hamartoma (i.e., cortical bone where medullary bone should be). Nonhomogeneous or multiple lesions are cause for concern, as they may indicate osteoblastic activity related to an underlying marrow-replacing disease such as metastasis (Figure 3).