Thallium-201 accumulation in myositis ossificans and in juxta-articular ossification

We present the findings on Tl-201 and Tc-99m-MDP scintigraphy in three patients suffering from heterotopic ossification (two patients presenting with myositis ossificans and one patient presenting with juxta-articular ossification in combination with myositis ossificans). Since resection of the lesions has to be delayed until stabilization, Tc-99m-MDP is Often used as a parameter of lesional activity, although it is not optimal. For this clinical problem, we evaluated Tl-201 scintigraphy as a marker of metabolic activity. In addition to the well-documented uptake of Tc-99m-MDP, marked accumulation of Tl-201 was observed in all heterotopic ossification sites. Hence, our results support the use of Tl-201 scintigraphy in the therapeutic management and monitoring of conditions associated with ectopic ossification. On the other hand, although myositis ossificans is sometimes clinically, radiographically and even histologically confused with extraosseous osteogenic sarcoma, Tl-201 accumulation may not be a helpful factor in the differential diagnosis due to the presence of tracer accumulation in both disorders