{"id":499,"date":"2024-06-28T04:09:46","date_gmt":"2024-06-28T04:09:46","guid":{"rendered":"https:\/\/orthopaedicsone.com\/port\/portnotes-primary-low-grade-intramedullary-osteosarcoma\/"},"modified":"2024-06-28T04:09:46","modified_gmt":"2024-06-28T04:09:46","slug":"portnotes-primary-low-grade-intramedullary-osteosarcoma","status":"publish","type":"page","link":"https:\/\/www.orthopaedicsone.com\/port\/portnotes-primary-low-grade-intramedullary-osteosarcoma\/","title":{"rendered":"Primary, Low-Grade Intramedullary Osteosarcoma"},"content":{"rendered":"<h3>DEFINITION AND PATHOGENESIS<\/h3>\n<ul>\n<li>Variants of osteosarcoma that display low-grade histologic anaplasia coupled with a low biologic grade (metastatic rate in the range of 10%) are defined as a low-grade osteosarcoma<\/li>\n<li><em>The &quot;sclerosing&quot; variant of osteosarcoma has extremely innocent, &quot;normalized&quot; nuclei that may show a cytologic grade of 0, but are typically of biologic grade 2-3 (metastatic rate in the range of 40-50%)(cannot be defined as low grade)<\/em><\/li>\n<\/ul>\n<h3>IMPORTANCE<\/h3>\n<ul>\n<li>When difficult to diagnose, lesions are often mistaken for a benign bone tumor<\/li>\n<li>Misdiagnosis is associated with an ?risk of transformation to a conventional, high-grade osteosarcoma with full metastatic potential<\/li>\n<li>&lt;2% of osteosarcomas are low-grade lesions<\/li>\n<li>The overall incidence of biopsy-analyzed primary bone tumors is therefore 1% (about equivalent to the frequency of chondroblastoma)<\/li>\n<li>On average, patients are about one decade older than those with conventional osteosarcoma (70% 18-40 yrs of age)(wide range: 15-83 yrs of age)<\/li>\n<\/ul>\n<h3>CLINICAL FEATURES<\/h3>\n<ul>\n<li>Pain and\/or swelling (average duration of sxs 44 mos, ranging from 1-180 mos)<\/li>\n<\/ul>\n<h3>RADIOLOGIC FEATURES<\/h3>\n<ul>\n<li>Almost any bone can be involved, but sites are predominantly in long bones (85%), esp LEs<\/li>\n<li>Most affect the metaepiphyseal region of the bone, in contrast to the more usual metaphyseal to metadiaphyseal location of conventional osteosarcoma<\/li>\n<li>The typical case is characterized by:<\/li>\n<li>Bone expansion caused by slow growth of the tumor<\/li>\n<li>Bone production in most instances, imparting a hazy to &quot;ground glass&quot; appearance similar to fibrous dysplasia<\/li>\n<li>Irregular cortical erosion, imparting a coarsely trabeculated pattern<\/li>\n<li>A generalized lack of symmetry or uniformity<\/li>\n<li>Unusual findings<\/li>\n<li>Pure intralesional lucency<\/li>\n<li>Densely blastic<\/li>\n<li>Surrounding host bone sclerosis<\/li>\n<li>Ominous periosteal reactions<\/li>\n<li>Osteochondroma-like nubbins<\/li>\n<\/ul>\n<h3>GROSS PATHOLOGY<\/h3>\n<ul>\n<li>Most lesions are white and gritty, related to the production of fibrous and bony tissues<\/li>\n<\/ul>\n<h3>HISTOLOGIC FEATURES<\/h3>\n<ul>\n<li>At least four histologic variants are noted:<\/li>\n<li>Fibrous dysplasia-like<\/li>\n<li>Nonossifying fibroma-like<\/li>\n<li>Osteoblastoma-like<\/li>\n<li>Chondromyxoid fibroma-like<\/li>\n<li>Diagnosis is made be finding one or more of the following:<\/li>\n<li>Subtle cytologic anaplasia and increased mitoses beyond the range of the benign lesion it mimics<\/li>\n<li>Abnormal radiologic patterns that are consistent with a low-grade malignancy but not with the benign histologic lesion it mimics<\/li>\n<li>Unexplained stubborn recurrences for as many as 12 years after the diagnosis of one of the four benign lesions mentioned previously, coupled with the eventual development of clear-cut anaplasia and\/or metastases<\/li>\n<li>Most such cases with obvious malignant change are misdiagnosed as a benign lesion that has undergone malignant transformation rather than as a low-grade osteosarcoma with eventual change into a conventional osteosarcoma<\/li>\n<\/ul>\n<h3>DIFFERENTIAL CLINICOPATHOLOGIC DIAGNOSIS<\/h3>\n<ul>\n<li>Fibrous dysplasia<\/li>\n<li>NOF<\/li>\n<li>Enchondroma<\/li>\n<li>UBC<\/li>\n<li>Chondrosarcoma<\/li>\n<li>Desmoplastic fibroma<\/li>\n<li>Chondromyxoid fibroma<\/li>\n<\/ul>\n<h3>DISEASE COURSE AND TREATMENT<\/h3>\n<ul>\n<li>As long as the tumor is of low grade, the metastatic rate is low (about 10% or less)<\/li>\n<li>&quot;The intramedullary counterpart of parosteal osteosarcoma&quot;<\/li>\n<li>Wide resection (intralesional excision results in 100% LR)<\/li>\n<li>LR can be higher grade or even dedifferentiated<\/li>\n<li>5- and 10-yr survival 90% and 85%<\/li>\n<li>Reconstruction of a 20cm tibial defect after wide resection using an Ilizarov technique has been described<\/li>\n<\/ul>\n<h3>SPECIAL CONSIDERATION<\/h3>\n<ul>\n<li><strong><em>MULTICENTRIC LOW GRADE OSTEOSARCOMA<\/em><\/strong><\/li>\n<li>Has been reported<\/li>\n<\/ul>\n<h3>FIGURES<\/h3>\n<\/p>\n<table>\n<tr>\n<td>There are no images attached to this page.<\/td>\n<\/tr>\n<\/table>\n<h3>REFERENCES<\/h3>\n<p>Barbara C, Tornetta P, III, Vigorita VJ, Zilles M, Etienne G: Leg pain in an 11-year-old boy. Clin Orthop 363:264-7,70-2,1999.<br \/><\/br> McCarthy EF, Tolo VT, Dorfman HD: Multicentric metachronous, low-grade sclerosing osteogenic sarcoma. Skeletal Radiol 16:592-6,1987.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>DEFINITION AND PATHOGENESIS Variants of osteosarcoma that display low-grade histologic anaplasia coupled with a low biologic grade (metastatic rate in the range of 10%) are defined as a low-grade osteosarcoma The &quot;sclerosing&quot; variant of osteosarcoma has extremely innocent, &quot;normalized&quot; nuclei that may show a cytologic grade of 0, but are typically of biologic grade 2-3 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_lmt_disableupdate":"","_lmt_disable":"","footnotes":""},"class_list":["post-499","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.orthopaedicsone.com\/port\/wp-json\/wp\/v2\/pages\/499","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.orthopaedicsone.com\/port\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.orthopaedicsone.com\/port\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.orthopaedicsone.com\/port\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.orthopaedicsone.com\/port\/wp-json\/wp\/v2\/comments?post=499"}],"version-history":[{"count":0,"href":"https:\/\/www.orthopaedicsone.com\/port\/wp-json\/wp\/v2\/pages\/499\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.orthopaedicsone.com\/port\/wp-json\/wp\/v2\/media?parent=499"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}