Skeletal Radiol (1997) 26:501–504 501 © International Skeletal Society 1997 CASE REPORT

&roles:David B. Stafford Johnson Extraskeletal mesenchymal chondrosarcoma William Breidahl Joel S. Newman of the rectus sheath Kenneth Devaney Alan Yahanda

&p.1:Abstract Mesenchymal chondrosar- &kwd:Key words Mesenchymal chondro- D.B. Stafford Johnson, M.S.c., M.R.C.P.I., F.F.R. (✉) · W. Breidahl, M.B.B.S. comas (MSCs) are a rare form of sarcoma extraskeletal&bdy: J.S. Newman, M.D. chondrosarcoma which usually arise Department of Radiology, in bone. Extraskeletal chondro- University of Michigan Medical Center, sarcomas constitute a minority 1500 East Medical Center Drive, Ann Arbor, MI 48109–0030, USA (14–25%) of MSCs. We describe the imaging features of an extraskeletal K. Devaney, M.D. mesenchymal chondrosarcoma that Department of Pathology, University of Michigan Medical Center, arose from the rectus abdominus Ann Arbor, Michigan, USA muscle. A. Yahanda, M.D. Department of Surgery, University of Michigan Medical Center, Ann Arbor, Michigan, USA&/fn-block:

Case report and US findings, the diagnosis of soft tissues. Its cut section was gray- chondrosarcoma was considered. white and cut with a gritty texture; A 40-year-old woman presented with MR images were obtained for multi- the mass was solid without cystic a 6-week history of a progressive planar evaluation of the mass prior to change. Histologic analysis revealed painless swelling of the lower anteri- surgery. The mass appeared isoin- a mesenchymal chondrosarcoma or abdominal wall. Clinical examina- tense to muscle on T1-weighted se- with evidence of microscopic in- tion revealed a 4×5-cm non-fluctu- quences and exhibited heterogeneous volvement of the periosteum of the ant, non-tender mass. Ultrasound high signal on T2-weighted and pubic symphysis (Figs. 5, 6). In ar- (US) examination using a linear STIR sequences. It demonstrated eas of the tumor, some of the carti- 7.5 MHz transducer revealed a large heterogeneous enhancement follow- laginous islands were calcified. solid heterogeneous mass arising ing intravenous gadolinium adminis- from the anterior abdominal wall; tration (Fig. 3). MRI confirmed the the mass contained scattered areas of origin of the mass from the rectus Discussion increased echogenicity with distal muscle and demonstrated normal shadowing consistent with calcifica- bone marrow in the symphysis pubis. Mesenchymal chondrosarcoma tion (Fig. 1). Increased vascularity Scattered areas of low signal within (MSC), originally described by Lich- within the mass was demonstrated the mass on all MR sequences, con- tenstein and Bernstein [1] in 1959, on color-flow Doppler. CT demon- sistent with calcification, were pres- represents approximately 1% of all strated a 5×6-cm soft tissue mass ent (Fig. 4). The patient underwent osseous chondrosarcomas. While the containing numerous areas of coarse wide surgical excision of the mass majority of MSCs are skeletal tu- calcification that was intimately re- including resection of a portion of mors, they may also arise in the soft lated to the rectus muscle (Fig. 2) the pubic symphysis. Grossly, the tissues; the first case of extraskeletal and extended inferiorly to abut the mass was solid, rubbery, and rather mesenchymal chondrosarcoma symphysis pubis. Based on the CT well demarcated from the adjacent (ESMC) was described in 1964 [2]. 502

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Fig. 1 Longitudinal sonogram of the ante- Fig. 2 Axial CT scan above the symphysis considerable enhancement with irregular rior abdominal wall proximal to the sym- pubis. The mass (arrow) extends posterior- areas of low signal interspersed&/fig.c: physis pubis. There is a well-defined het- ly from the rectus abdominal muscle. erogeneous mass (arrows) contiguous with Coarse calcifications are present within the Fig. 4 Axial T2-weighted MR image the rectus abdominus muscle (arrow- mass&/fig.c: (TR=3500,TE=85) with fat saturation dem- heads). The mass contains central foci with onstrates a lobulated, predominantly high- distal acoustic shadowing consistent with Fig. 3 Axial T1-weighted MR image signal mass with intervening low signal in- calcification&/fig.c: (TR=500,TE=26) with fat saturation fol- tensity foci, some of which appear as sep- lowing intravenous administration of gado- tations&/fig.c: linium. The mass (arrow) demonstrates 503

Approximately 14%–25% of excluded a diagnosis of myositis os- showed inhomogeneous or homoge- MSCs occur in extraskeletal sites [3, sificans or hematoma. The largest se- neous enhancement corresponding to 4]. Unlike conventional chondrosar- ries of ESMC to date was reported highly cellular areas on histologic comas, ESMCs have a female pre- by Shapeero et al. [9] who described analysis. MR performed in four pa- ponderance and occur most frequent- the plain radiography, CT, and MR tients in the series reported by Sha- ly in the brain, meninges, and lower features in seven patients with peero showed ESMC as a soft tissue extremities [5]. There are two princi- ESMC. In that series, four of seven mass isointense with muscle on T1- pal age groups in which ESMC oc- cases (57%) demonstrated a soft tis- weighted sequences with high signal cur: those that arise in the central sue mass with arc, ringed, or stippled on T2-weighted and proton density nervous system characteristically oc- calcification on plain radiography. sequences; two of four cases in this cur in the 20- to 30-year age group; On CT, a soft tissue mass with pre- study exhibited enhancement with ESMCs that arise in soft tissues usu- dominantly peripheral enhancement gadolinium. In our case, the tumor ally occur in patients older than 40 following intravenous contrast was exhibited gadolinium enhancement years of age [6]. evident, which contained focal low in an inhomogeneous fashion; there There have been few reports of attenuation areas possibly represent- was also evidence of lobulation. The the imaging features of ESMC. In ing necrosis. Coarse calcification on high signal of ESMC on T2-weight- this case, US was the initial radio- CT was demonstrated in four of six ed sequences may reflect foci of car- logic investigation. There has been patients (67%). In our case, exten- tilage and/or undifferentiated mesen- only one prior case report [7] that sive calcification was demonstrated chymal cellular component. ESMCs detailed the US findings of an on the non-contrast scan; the mass in general have few cartilaginous el- ESMC, which also occurred in the exhibited generalized enhancement ements with a predominance of the rectus sheath. The authors docu- following the administration of con- mesenchymal component. mented the usefulness of US to de- trast. The histopathologic differentia- fine the extent of the ESMC and also MR imaging may help to distin- tion of MSC from malignant heman- noted the tumor’s relative sonolucen- guish between various types of carti- giopericytoma and chondrosarcoma cy, which was attributed to its myx- laginous tumor. The signal intensity may be difficult [12]. The presence oid content; this report, however, did of cartilaginous tumors is dependent of diffusely distributed islands of not illustrate any histologic findings. on their cellular content [10]. The cartilage with a low-grade cytologi- US evaluation of soft tissue neo- more cellular cartilaginous tumors, cal appearance throughout the tumor plasms has previously been reported such as chondroblastomas or clear- in association with an undifferentiat- by several authors; the largest series cell chondrosarcomas, demonstrate ed round to oval cellular component comprised 50 soft tissue tumors, 14 an amorphous configuration that is is characteristic of MSC. of which were malignant [8]. Char- isointense or hypointense to muscle Hemangiopericytomas are com- acteristic, but non-specific, features on T2-weighted images. Other carti- posed of a dense network of vascular of malignancy included a discrete le- laginous tumors, such as enchondro- structures about which are arrayed sion with ill-defined margins, hetero- mas and well-differentiated chondro- round to oval tumor cells; lacking in geneous echotexture, and hypoecho- sarcomas, which are less cellular tu- hemangiopericytomas, however, are genicity relative to the surrounding mors, display a homogeneous high the cartilaginous islands that typify tissues. These findings were present signal intensity on T2-weighted se- the MSC. in our case. US also demonstrated quences that is thought to reflect the Treatment of ESMC consists of scattered foci of calcification and hyaline cartilage with its low cellu- wide surgical excision; the role of blood flow within the mass, which larity and high water content. These adjuvant chemotherapy and radio- hyaline cartilaginous tumors also ex- therapy is uncertain. In a review of hibit a lobular configuration divided 111 cases by Nakashima et al. [13],

▲ Fig. 5 On medium power examination, the by low-intensity septae consisting of no difference in survival was found tumor consisted of two components: is- fibrous tissue. A recent study at- between bone and soft tissue mesen- lands of cartilage, shown here, in which in- dividual tumor cells were distributed tempted to characterize cartilaginous chymal chondrosarcomas. The mean throughout a chondroid matrix, and a tumors by means of their enhance- survival rate in 35 patients in a study round cell component, shown in Fig. 6 (he- ment patterns following gadolinium by Huvos et al. was 37.9 months [4] matoxylin and eosin, ×175)&/fig.c: administration. Maartje et al. [11] . Frequent and long-term follow up Fig. 6 On closer scrutiny, the round cell demonstrated that low grade chon- is necessary if local recurrence is to component of the mesenchymal chondro- drosarcomas characteristically exhib- be detected at an early stage. Local sarcoma consists of a relatively homogene- it septal enhancement corresponding recurrence is common and usually ous population of round to oval cells with- out striking nuclear pleomorphism or abun- to fibrovascular septation between precedes metastatic disease in the dant mitotic figures (hematoxylin and eo- the lobules of hyaline cartilage. lungs. sin, ×350) High-grade chondrosarcomas 504

References 5. Wu KK, Collon DJ, Guise ER. Extra- 10. Cohen EK, Kressel HY, Frank TS, Fall- osseous chondrosarcoma: report of five on M, Burk DL, Dalinka MK, 1. Lichtenstein L, Bernstein D. Unusual cases and review of the literature. J Schiebler ML. Hyaline cartilage-origin benign and malignant chondroid tu- Bone Joint Surg Am 1980; bone and soft-tissue neoplasms: MR mors of bone. Cancer 1959; 62:189–194. appearance and histologic correlation. 12:1142–1147. 6. Louvet C, Gramant A, Krulik M, Jag- Radiology 1988; 167:477–481. 2. Dowling EA. Mesenchymal chondro- ueux M, Hubert D, Brissaud P, Sirinelli 11. Maartje JA, Bloem JL, Eulderink F, sarcoma. J Bone Joint Surg 1964; A, Augereau B, Tubiana J, Debray J. Hogendoorn PC, Taminiau AHM. Car- 46:747–754. Extraskeletal mesenchymal chondro- tilaginous tumors: correlation of gado- 3. Guccion J, Font R, Enzinger F, Zim- sarcoma: case report and review of the linium-enhanced MR imaging and his- merman L. Extraskeletal mesenchymal literature. J Clin Oncol 1985; topathological findings. Radiology chondrosarcoma. Arch Pathol 1973; 3:858–863. 1993; 186:813–817. 95:336–340. 7. O’Malley BP, Qizilbash AH. Mesen- 12. Bertoni F, Picci P, Bacchini P, Capanna 4. Huvos AG, Rosen G, Dabska M. Mes- chymal chondrosarcoma of the rectus R, Innao V, Bacci G, Campanacci M. enchymal chondrosarcoma. A clinico- sheath: case report with ultrasonic find- Mesenchymal chondrosarcoma of bone pathological analysis of 35 patients ings. J Clin Ultrasound 1977; and soft tissues. Cancer 1983; with emphasis on treatment. Cancer 5:348–349. 52:533–541. 1983; 51:1230–1237. 8. Lange TA, Austin CW, Seibert JJ, Ang- 13. Nakashima Y, Unni KK, Shives T, tuaco TL, Yandow DR. Ultrasound im- Swee RG, Dahlin DC. Mesenchymal aging as a screening study for malig- chondrosarcoma of bone and soft tis- nant soft tissue tumours. J Bone Joint sues. Cancer 1986; 57:2444–2452. Surg Am 1987; 69:100–105. 9. Shapeero D, Vanel D, Couanet D, Con- tesso G, Ackerman L. Extraskeletal mesenchymal chondrosarcoma. Radiol- ogy 1993; 186:819–826.

60th Annual Course: VII Alex Norman Lectureship Series ANNOUNCEMENTS Radiology 1997 – Thoraco-Abdominal Imaging in Radiology: Advanced Musculoskeletal September 11–13, 1997 Imaging – The Shoulder Minneapolis, MN, USA December 9, 1997 European Spine Society Fee: $395. New York, NY, USA 8th Annual Meeting For further information please contact: Sponsored by: Hospital for Joint Disease, September 10–13, 1997 Office of Continuing Medical Education, New York, NY, New York University Kos, Hellas, Greece University of Minnesota, Suite 107, School of Medicine. Faculty: D. Resnick, For further information please contact: 615 Washington Avenue S.E. V. Chandnani, J. Beltran, J. Brown, E.P. Velikas, M.D. Minneapolis, MN 55414, N. Schoenberg, J. Zuckerman, A. Rokito, (Organizing Committee), Tel.: (612)626-7600 D. Rose, F. Cuomo, M. Rafü. 18 Ipsilandou Str.-Kolonaki, or Toll Free 1-800-776-8636, Registration fee: Physicians $100, GR-106 76 Athens, Greece. Fax: (612)626-7766, Residents/Technologists $50. Tel. (+30)1-7249050, Fax (+30)1-7241003; Internet: http://www.cee.umn.edu:80/cme/ For further information please contact: or J. Reichert Schild (Scientific Secretariat), MS. Cathy Smith, Seefeldstrasse 16, World Congress on Medical Physics Tel.: (212)598-6373, CH-8610 Uster, Switzerland. and Biomedical Engineering Fax: (212)598-6125. Tel. (+41)1-9941404, Fax (+41)1-9941403. September 14–19, 1997 Nice, France For further information please contact: Nice97, See, General Secretariat, 48 rue de la Procession, F-75724 Paris Cedex 15, France. Tel.: +33 1 44 49 60 60, Fax +33 1 44 49 60 44, e-mail: [email protected].

2nd Interventional MRI Symposium October 17–18, 1997 Düsseldorf, Germany For further information please contact: PD Dr. Thomas Kahn, Institut für Diagnostische Radiologie, Heinrich-Heine-Universität, Moorenstrasse 5, D-40225 Düsseldorf, Germany. Tel. +49-(0)2 11-8 11-77 52/87 67, Fax +49-(0)2 11-8 11-61 45, e-mail: [email protected], http://www.mr.uni-duesseldorf.de