An unusual finding on a pelvic radiograph

A 74 year old man presented to the ear, nose, and throat department with breathlessness on exertion, intermittent voice hoarseness, and a sensation of catarrh in his throat. After a laryngoscopy with biopsy was performed, he was diagnosed as having a low grade chondrosarcoma of the larynx. Before surgical debulking of the lesion was carried out he underwent computed tomography of the chest, abdomen, and pelvis. This confirmed the presence of a subglottic mass in the larynx but also showed a mixed lytic and sclerotic expansile lesion (5.8 cm (longitudinal)×1.6 cm (axial)×4.5 cm) in the left iliac blade of the pelvis. The pelvic lesion was well corticated, with internal ossified septae and calcification. Expansion of the left iliac wing was noted, with no breach in the cortex. He had no symptoms other than those that he presented with, which resolved after surgical debulking of the chondrosarcoma. He denied any pain and was independently mobile with a normal gait. He had never smoked and drank less than 7 units of alcohol a week. He had no comorbidities and was not taking any drugs. All blood results and a chest radiograph were normal. A plain radiograph of the pelvis was taken to help characterise the pelvic lesion. This showed a solitary well corticated lesion in the left iliac bone. There was evidence of ossification within the lesion but an absence of periostitis (figure⇓). Calcification of the lesion, endosteal scalloping, and expansion of …