Osteopathia Striata with Concomitant Fibroblastic Osteosarcoma of the Femur. A Potential Malignant Risk?

We report a case of a 33-year old female with an unusual presentation of high-grade osteosarcoma superimposed on osteopathia striata. Few cases of malignancy arising in sclerosing bone dysplasia have been reported in literature. Of the few reported ones, osteosarcoma was associated with melorheostosis in two cases, with osteopoikilosis in the one case, and with combined melorheostosis and osteopathia striata in one case. To the best of our knowledge the current case is the first one of a high-grade osteosarcoma arising from isolated osteopathia striata, not combined with other forms of sclerosing bone dysplasia. Introduction Osteopathia striata is an uncommon sclerosing bone dysplasia that remains mostly asymptomatic. First described by Voorhoeve in 1924 [1], it is characterized by linear streaks of altered bone density in the metaphyses and diaphyses of long bones, pelvis, and scapulae, thought to arise from disturbances in the endochondral bone formation. Initially thought to be an autosomal dominant disorder, recent molecular analysis confirmed an X-linked dominant inheritance, with germline mutations of the WTX gene, causing osteopathia striata congenita with cranial sclerosis [2]. The radiologic findings of osteopathia striata are characteristic, suggesting the diagnosis; however, the molecular analysis can confirm it . Here we report an unusual case of high-grade osteosarcoma likely arising from osteopathia striata. We review the literature and attempt to clarify questions of potential malignant risk associated with sclerosing bone dysplasia. To our knowledge, only one case of osteosarcoma arising in a background of osteopathia striata combined with melorheostosis has been reported in literature, but none of osteosarcoma arising from isolated osteopathia striata. Case Report A 33-year-old woman presented with pain in the left thigh. Imaging revealed a diaphyseal soft tissue mass superimposed on a previously undetected benign sclerotic condition of the left femur, in the background of sclerosis (Figure 1). Endosteal scalloping was present in the femoral diaphysis, suggesting a slowly growing process, possibly a malignant transformation taking place in an otherwise benign bone condition. The distal femoral metaphysis and the proximal tibia showed radiographic changes consistent with osteopathia striata (Figures 2 and 3). Radiographic characteristics consistent with osteopathia striata were also appreciated in the patient’s contralateral lower extremity (right femur, tibia, and fibula Figure 4). Abnormality in the left ileosacral region was also noted. A needle biopsy of the diaphyseal soft tissue mass indicated malignancy; an 8-cm mass was removed during a subsequent extraarticular surgery with diaphyseal allograft placement (Figure 5). Decalcified sections of the tumor with bone revealed abundant malignant osteoid formation in a high-grade osteosarcoma of the femoral diaphysis, with prominent fibroblastic features, in a background of extensive sclerosing bone dysplasia, prominent cement lines, and focal marrow fibrosis, consistent with osteopathia striata (Figures 6-8). Areas of woven bone were also present on polarized light examination (Figure 9). Many areas of osteosarcoma displayed features morphologically indistinguishable from leiomyosarcoma. Immunohistochemical markers were negative for desmin, actin, CD34, S-100, and wide spectrum keratins. The soft tissue portion of the tumor showed foci of malignant osteoid formation. Postoperative imaging showed characteristics of osteopathia striata in the residual distal femoral and proximal tibial metaphyses. Radiographs in four other family members (father, mother, brother and daughter) showed changes consistent with osteopathia striata in father and brother (Figures 10 and 11). Figure 1: X-ray Osteosarcoma in the background of osteopathia striata, left femur diaphysis. Citation: Rafael OC, Kahn L, Rosen G, Aziz M (2015) Osteopathia Striata with Concomitant Fibroblastic Osteosarcoma of the Femur. A Potential Malignant Risk? J Orthop Oncol 1: 104. doi:10.4172/2472-016X.1000104