Which Emerges First: Bone Marrow Edema or Nidus in Osteoid Osteoma?

This case report describes a well-documented birth and evolution of an osteoid osteoma at the talus. Although initial radiologic images indicate mild bone marrow edema at first (without nidus), subsequent magnetic resonance imaging and computed tomographic images reveal pathognomonic nidus at the talus. During the evolution of the lesion, typical night pain was coincident with the occurrence of the nidus, as seen on magnetic resonance imaging. This may be interpreted that nidus formation may be related to the night pain. In this report, the first finding was bone marrow edema. Although our classic knowledge was that the edema follows the lesion, this report makes a difference. The relationship between bone marrow edema and osteoid osteoma has not been questioned in the literature before. We speculate that this report brings to mind, the question of which comes first? A bone marrow edema or nidus? Another question is: Does osteoid osteoma always start with such a dust cloud in the bone as we presented herein?