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1. Introduction
Hemopoietic marrow predominates in the bony pelvis until late in life. Metastatic disease, plasma cell myeloma, Ewing’s sarcoma, and lymphoma are among the tumors that primarily localize to hematopoietic marrow. The tendency for these neoplasms to involve both the axial and appendicular skeleton in the young and predominantly the axial skeleton in the middle aged and elderly is consistent with the changing distribution of red marrow that occurs with advancing age. The variability in the appearances of both primary and secondary pelvic tumors may lead to diagnostic difficulty, especially in the setting of differentiating primary tumors from metastasis. In the first part of this paper we discussed imaging techniques, the role of biopsy, and the influence of age in the differential diagnosis of tumors of pelvis. We also reviewed the radiological appearances of common benign bone tumors of the pelvis. The aim of this paper is to review the multimodality appearances of common malignant tumors of the bony pelvis and frequent mimics.
2. Recent Advances
Despite significant advances in other modalities, radiographs remain the mainstay for initial assessment and diagnosis of bone tumors [1, 2]. Current multidetector-row computed tomography (MDCT) is better than magnetic resonance imaging (MRI) in the assessment of bone tumor characteristics like subtle cortical breach and periosteal reaction and in classifying matrix mineralization [1]. MRI remains superior to CT in assessing the involvement of soft tissue, marrow, and neurovascular structures [2]. Limb salvage surgical techniques are now preferred to amputation because of equal or better long-term survival rates, feasibility of resection of distant metastasis, and improved functional results [2, 3]. Because of consideration of limb-sparing surgery, the biopsy tract (which needs to be resected along with the tumor as it may be contaminated) should not traverse the uninvolved compartments. Specifically, the gluteal musculature and rectus femoris should not be in the biopsy tract as these muscles need to be preserved for postoperative rehabilitation and stabilization of the prosthesis. It is ideal to discuss the biopsy approach with the referring oncological surgeon. A higher diagnostic yield can be achieved by targeting nonsclerotic, nonnecrotic areas and obtaining more tissue with larger bore needles and multiple passes [4, 5].
3. Malignant Tumors (below the Age of 40 Years)
3.1. Osteogenic Sarcoma (OGS)
Conventional...