Introduction: Enostosis or bone island is a common incidental finding. These benign developmental lesions represent foci of cortical bone embedded within the trabecular network of cancellous bone. They are usually solitary and may be found in any bone but skull involvement is unusual.
Methods: We saw a 49-year old woman for a second opinion on disseminated spinal lesions on CT and MRI scans which were suspected to be osteoblastic metastases. She underwent surgery and radiation therapy for bilateral breast cancer in 2013 and took tamoxifen. She was in good general condition and had no axial complaints.
Results: CT scans showed numerous osteodense circular and ovoid lesions with speculated margins and normal surrounding bone in the pelvis, lumbar and thoracic vertebrae, sternum, scapula, humerus, ribs and clavicles. The lesions were hypointense on STIR and T1-weighted MRI images and were surrounded by normal signals. Cortices were intact. Bone scintigraphy, tumour markers and calcium metabolism were normal. Extensive imaging did not reveal extraskeletal metastases. A cervical and thoracic spine MRI, performed in 2009 for neck complaints showed the same lesions, unchanged to the recent and current images. X-rays taken in 2012 for joint complaints showed bone islands around the elbows and in the hands. The suspicion of osteoblastic metastatic disease was rejected.
Conclusion: We present a not earlier described skeletal condition, which we name osteoinsulosis disseminata. This benign condition consists of numerous bone islands diffusely spread throughout the skeleton. The single lesions have the typical imaging characteristics of enostosis. Osteoinsulosis disseminata differs from osteopoikilosis by the presence of numerous lesions in the axial skeleton and by the absence of longitudinal bone lesions. Bone scintigraphy is helpful to distinguish this benign condition from osteoblastic metastatic disease.
Disclosure: The authors declared no competing interests.