Transformation of Ischial Osteoblastoma Into High-Grade Osteoblastoma-Like Osteosarcoma

Abstract

The authors report an osteoblastoma-like variant of osteosarcoma of the right ischial tuberosity in a 14-year-old boy. Radiographs initially showed a bone-forming lesion of the right ischial tuberosity. The patient underwent biopsy with curettage and bone grafting, with final pathology revealing osteoblastoma. Two years after the initial procedure, he presented with exuberant bone formation about the operative site concerning for recurrence. He underwent a second biopsy that showed transformation into a high-grade osteoblastoma-like osteosarcoma. Results from staging studies were negative for distant metastatic disease. The patient was treated with standard 3-drug chemotherapy along with wide resection of the right ischium with periacetabular reconstruction and total hip arthroplasty. [ Orthopedics. 2019; 42(3):e343–e345.]

A complex histopathological challenge: suspicion of an osteoblastoma-like osteosarcoma arising from the second thoracic vertebra in a cat

“…Reasons for the difficulties in diagnosing primary bone tumours are on one side the overlap in histopathological and diagnostic imaging features among the different types (i. e. osteoblastoma and osteoid osteoma, low-grade osteosarcoma and aggressive osteoblastoma) [ 9 , 19 , 20 , 22 , 31 , 36 – 38 ] and on the other side the ability of malignant transformation [ 27 , 29 , 38 – 40 ]. In human medicine, this results in the definition or redefinition of different subtypes of osteosarcoma and osteoblastoma [ 18 , 22 , 41 ].…”

“…In human literature, the term OBLOS indicates an osteosarcoma, that may resemble osteoblastoma clinically, histologically and radiologically and have the capability for metastasis. However, conflicting information concerning the capacity to metastasize of this type of tumour exists [ 18 , 19 , 23 – 25 , 27 , 33 , 40 , 42 – 46 ].…”