An Unusual Presentation of Low Grade Central Osteosarcoma in the Distal Femur of a Sixty-eight Year Old Male Mimicking Fibrocartilaginous Mesenchymoma

Yilan Li, MD, PhD, Patrick Henn, MD, Tieying Hou, MD, PhD, Elizabeth Korangy, MD


Low grade central osteosarcoma is a rare intramedullary bone tumor that presents a diagnostic challenge due to its radiographic and histologic overlap with other low grade intraosseous lesions. Here we report a case of a 68 year old male presenting with local pain in the right distal thigh. An MRI study showed a 4.8 cm lesion in the metadiaphysis of the distal femur with extension into the cortex and aggressive periosteal reaction. Multiple biopsies were performed in an attempt to reach a conclusive diagnosis: 1) A CT guided FNA and biopsy revealed a low nuclear grade spindle cell neoplasm with new bone formation; 2) Subsequent core biopsy showed bland cartilage with no atypical features and reactive new bone formation; 3) An excisional biopsy was reported as a matrix (hyaline cartilage and bone) producing neoplasm showing features most consistent with fibrocartilaginous mesenchymoma. Due to uncertain malignant potential, the patient underwent complete resection of the distal femur with the final diagnosis of low grade central osteosarcoma.  Molecular studies performed showed lack of CPM amplification. This case report illustrates the diagnostic challenge of an atypical case of low grade central osteosarcoma.  It required multiple procedures, molecular studies, and correlating the histology to the radiology and clinical picture to arrive at the correct diagnosis.

[N A J Med Sci. 2016;9(2):78-82.   DOI:  10.7156/najms.2016.0902078]


Aneurysmal bone cyst (ABC), dedifferentiated chondrosarcoma (DDCS), fibrocartilaginous mesenchymoma (FCM), fibrous dysplasia (FD), fibrocartilaginous dysplasia (FCD), low grade central osteosarcoma (LGCO)

Full Text:



Kurt AM, Unni KK, McLeod RA, Pritchard DJ. Low-grade intraosseous osteosarcoma. Cancer. 1990;65:1418-1428.

Malhas AM, Sumathi VP, James SL, et al. Low-grade central osteosarcoma: a difficult condition to diagnose. Sarcoma. 2012;2012:764796.

Andresen KJ, Sundaram M, Unni KK, Sim FH. Imaging features of low-grade central osteosarcoma of the long bones and pelvis. Skeletal Radiol. 2004;33:373-379.

Kumar A, Varshney MK, Khan SA, Rastogi S, Safaya R. Low grade central osteosarcoma--a diagnostic dilemma. Joint Bone Spine. 2008;75:613-615.

Franceschina MJ, Hankin RC, Irwin RB. Low-grade central osteosarcoma resembling fibrous dysplasia. A report of two cases. Am J Orthop (Belle Mead NJ). 1997;26:432-440.

Cozzutto C, Cornaglia-Ferraris P. Fibrocartilaginous mesenchymoma of bone. Pathol Res Pract. 1991;187:279-283.

Bulychova IV, Unni KK, Bertoni F, Beabout JW. Fibrocartilagenous mesenchymoma of bone. Am J Surg Pathol. 1993;17:830-836.

Gibson JN, Reid R, McMaster MJ. Fibrocartilaginous mesenchymoma of the fifth lumbar vertebra treated by vertebrectomy. Spine (Phila Pa 1976). 1994;19:1992-1997.

Dahlin DC, Bertoni F, Beabout JW, Campanacci M. Fibrocartilaginous mesenchymoma with low-grade malignancy. Skeletal Radiol. 1984;12:263-269.

Gedikoglu G, Aksoy MC, Ruacan S. Fibrocartilaginous mesenchymoma of the distal femur: case report and literature review. Pathol Int. 2001;51:638-642.

Lin J, Shulman SC, Steelman CK, et al. Fibrocartilaginous mesenchymoma, a unique osseous lesion: case report with review of the literature. Skeletal Radiol. 2011;40:1495-1499.

Takahashi Y, Oda Y, Yamamoto H, et al. Fibrocartilaginous mesenchymoma arising in the pubic bone: a case report. Pathol Int. 2013;63:226-229.

Martinez-Lage JF, Alarcon F, Hernandez-Barcelo JE, Almagro MJ, Alfaro R, Galera-Minarro A. Fibrocartilaginous mesenchymoma of the spine in a child: a case report. Childs Nerv Syst. 2010;26:385-389.

Dujardin F, Binh MB, Bouvier C, et al. MDM2 and CDK4 immunohistochemistry is a valuable tool in the differential diagnosis of low-grade osteosarcomas and other primary fibro-osseous lesions of the bone. Mod Pathol. 2011;24:624-637.

Jeon DG, Koh JS, Cho WH, et al. Clinical outcome of low-grade central osteosarcoma and role of CDK4 and MDM2 immunohistochemistry as a diagnostic adjunct. J Orthop Sci. 2015;20:529-537.

Erickson-Johnson MR, Seys AR, Roth CW, et al. Carboxypeptidase M: a biomarker for the discrimination of well-differentiated liposarcoma from lipoma. Mod Pathol. 2009;22:1541-1547.

Yoshida A, Ushiku T, Motoi T, et al. Immunohistochemical analysis of MDM2 and CDK4 distinguishes low-grade osteosarcoma from benign mimics. Mod Pathol. 2010;23:1279-1288.

Hatori M, Watanabe M, Okada K, Hosaka M, Kokubun S. Fibrocartilaginous mesenchymoma arising in the femur. Pathology. 2002;34:199-201.

Kumar V, Behera P, Shashikanth VS, Sudesh P. Congenital mesenchymoma of tibia: case report and review of literature. J Pediatr Surg. 2012;47:e17-20.

Masquijo JJ, Sartori F, Innocenti S. Fibrocartilaginous mesenchymoma of the proximal humerus: case report. Arch Argent Pediatr. 2014;112:e222-226.

Muthusamy S, Subhawong T, Conway SA, Temple HT. Locally aggressive fibrous dysplasia mimicking malignancy: a report of four cases and review of the literature. Clin Orthop Relat Res. 2015;473:742-750.

Sumner TE, Ward WG, Kilpatrick SE, Opatowsky MJ. Fibrocartilaginous mesenchymoma of bone: case report and review of the literature. Pediatr Radiol. 2000;30:315-317.


  • There are currently no refbacks.