Correlation between bone imaging and the clinical picture in two unsuspected cases of progressive diaphyseal dysplasia (Engelmann's disease).

Progressive diaphyseal dysplasia was incidentally discovered in two patients referred for Tc-99m MDP bone scintigraphy (one for intense sciatica, the other for the detection of breast cancer metastases). Tracer accumulation in the diaphyses of the lower limbs and the base of the skull was accompanied by bone thickening and patency of the medullary cavity, as demonstrated by radiography, MRI, and bone marrow scanning. Comparison of the clinical pictures with the results of instrumental examinations showed that these were cases of sporadic progressive diaphyseal dysplasia of slight and average gravity, respectively. The differentiation of Ribbing's disease is explained and reference also is made to a finding not mentioned in the literature, namely frontal bone resorption lacunules in one patient.