Osteosarcoma or Not: Diagnostic Challenges, Differentials and a few Clinical Cases

Abstract

Osteosarcoma, a mesenchymal tumor, arises from proliferation of malignant osteoblasts. It is important to observe clinical history, perform a thorough physical examination, and complete appropriate diagnostic testing to differentiate osteosarcoma from other conditions; whether neoplastic, trauma-induced or inflammatory in nature with similar compiled information and background. Cytology may serve as a screening tool to determine whether a swelling represents a neoplastic lesion or an inflammatory process. Benign processes may include inflammatory lesions such as an abscess; reactive conditions, such as hypersensitivity reactions; hematomas or seromas. Neoplastic conditions may also be benign, such as cysts, fibromas or adenomas or may be malignant. Malignant conditions may include, but are not limited to soft tissue sarcomas, fibrosarcomas or other sarcomas, adenocarcinomas or mast cell tumors, for example. Histopathology is generally considered the gold standard for determining the definitive diagnosis of a swelling. Additional diagnostics, such as immunohistochemistry, special staining, flow cytometry and PARR may be explored. The latter two diagnostics are especially useful to evaluate lymphoid neoplasia, whether lymphoma or leukemia. The goal of this manuscript is to discuss osteosarcoma, elucidate differentials that may appear cytologically similar and to briefly mention diagnostic tools that may help to arrive at a definitive diagnosis, as well as to rule out other causes of similar findings.