Chondroblastic, grade 3 periosteal osteosarcoma

Skeletal Radiol (1995) 24:69-71

Skeletal Radiology

Chondrob|astic, grade 3 periosteal osteosarcoma K.T. Wong, M.D., T. Haywood, M.D., M.K. Dalinka, M.D., B. Kneeland, M.D. Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA

Clinical information

Fig. 1. Anteroposterior plain radiograph. A soft tissue mass is present adjacent to the medial tibial metaphysis with irregularity of the cortex (arrowheads) and a Codman's triangle (arrow) Fig. 2. A Coronal and B axial Tl-weighted magnetic resonance images. A mass medial to the proximal tibia is isointense to muscle. No involvement of the adjacent medullary canal is seen

An 1 l-year-old girl presented to the hospital with a 5-day history of swelling and intermittent pain in the right proximal tibia. The pain was severe enough to awaken her at night and was not related to activity. There was no history of trauma, fever, chills, or weight loss. On physical examination, there was a palpable soft tissue mass over the medial aspect of the right proximal tibia. The proximal part of the right leg was slightly enlarged, measuring 31 cm in circumference at the level of the final tubercle as compared with a 30 cm circumference for the left leg. There was decreased range of motion at the knee, which could go from full extension to 30 ~ flexion. Plain radiographs (Fig. 1) demonstrated an elliptical mass adjacent to the medial proximal tibia with periosteal elevation and a Codman's triangle at the inferior margin of the lesion. No matrix calcification is evident. The cortex beneath the mass is irregular along its outer border, but the endosteal surface is grossly intact. Magnetic resonance imaging (MRI) demonstrated the mass to be isointense to muscle on T l - w e i g h t e d (TR600, T E l 2 ) images, of intermediCorrespondence to: Murray K. Dalinka, M.D., Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA

9 1995 International Skeletal Society

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K.T. Wong et al.: Chondroblastic osteosarcoma

Fig, 3, A Axial proton-density and B T2weighted images. The mass has an intermediate signal on the proton-density image and a high signal on the T2-weighted image. Abnormal signal is also present in the popliteus muscle (arrow)

Fig. 4. Gadolinium-enhanced axial T1weighted image, showing enhancement of the mass with a septated pattern. A thin rim of enhancing tissue is seenjust posterior to the tibia (arrowheads). The popliteus muscle also has abnormalenhancement

ate signal intensity on proton-density-weighted (TR2500, TE20) images, and of high signal intensity on T2weighted (TR2500, TE80) images (Fig. 2, 3). There was no involvement of the medullary canal. The lesion was subperiosteal in location and limited by the periosteum. The popliteus muscle had slight increase in signal intensity on the T2-weighted image which may be due to edema. On administration of intravenous gadolinium, the mass enhanced in a septated pattern, and a slender tendril of enhancing material extended from the main tumor mass posteriorly around the tibia (Fig. 4). The popliteus muscle also demonstrated minimal enhancement. Open biopsy was performed.

Diagnosis: Chondroblastic, grade 3 periosteal osteosarcoma The tumor was surrounded by a thick, white capsule. Several cubic centimeters of tissue were removed

for histologic examination. Microscopy at 10x magnification with hematoxylin and eosin staining revealed lobules of hypercellular cartilage with condensation of nuclei and formation of osteoid matrix towards the center of the lobule (Fig. 5). Higher power (40x) magnification showed ramifying matrix material between individual tumor cells (Fig. 6). The final diagnosis was chondroblastic, grade 3 periosteal osteosarcoma.

Discussion The radiographic appearance of this lesion, its location, and the age of the patient and presentation are all typical of periosteal osteosarcoma, which has been well described by Unni et al. [1] in a series of 23 patients. The most common age at presentation is the second and third decade, and there is a slight predominance of male patients. The two most common bones involved are the tibia and femur. Unlike parosteal osteosarcoma,

the anterior rather than the posterior aspect of the distal femur is involved. The nonenhanced MRI appearance of the lesion is merely what one would predict based on the pain film appearance. The lesion arises from the periosteal of the cortex. The MRI studies excluded marrow involvement and joint extension. The contrast-enhanced (gadolinium-DTPA) images depicted what has been described as a septal enhancement pattern typical of cartilage-containing lesions, particularly enchondromas and low-grade chondrosarcomas [2-4]. Aoki et al. [2] have reported a ring-and-arc enhancement with gadolinium in MRI studies in patients with enchondromas and chondrosarcomas. Varma et al. [4] have also noted septal and ring-and-arc enhancement of chondrosarcomas. Geirnaerdt et al. [3[ described a septal enhancement pattern in 24 of 27 low grade chondrosarcomas. Lloyd et al. [5] described peripheral enhancement of nasosinus chondrosarcomas, but their illustrations also showed septal enhancement within the lesion. It is thought that the enhancement pattern is a reflection of the typical lobulated growth pattern of cartilaginous tumors. The septal enhancement pattern in our patient with a high-grade periosteal osteosarcoma is thought to reflect its largely cartilaginous compostion. The contrastenhanced MRI images simulated an enchondroma or chondrosarcoma. The gross appearance of periosteal osteosarcoma is similar to that of cartilaginous tumors, which tend to be well circumscribed, lobulated, and have the pale blue appearance of cartilage. Longitudinal chalky striations may be seen in the center of the lobules. Microscopically, the tumor is composed of lobules of cartilage with moderate cytological atypia. The periphery of the lobules is hypercellular with sheets of spindle cells which contain lace-like osteoid between tumor cells, establishing the tumor as an osteosarcoma. The center of the chondroid lobules usually show trabecular-appearing bone. The tumor osteoid within a periosteal osteosarcorna is often spiculated and is typically perpendicular to the long axis of the bone, forming septations

K.T. Wong et al.: Chondroblastic osteosarcoma

Fig. 5. Photomicrograph depicting lobules of cartilage with peripheral condensation and formation of osteoid matrix towards center of the lobule, characteristic of periosteal osteosarcoma (H&E, x5.5) Fig. 6. Photomicrograph at higher magnification showing ramifying osteoid matrix between individual tumor cells (H&E, x22)

within the cartilaginous matrix. A small b i o p s y s p e c i m e n m a y occasionally be m i s t a k e n l y d i a g n o s e d as a periosteal c h o n d r o s a r c o m a if an adequate a m o u n t o f the osseous elements is not included in the specimen [6]. The distinction b e t w e e n a periosteal c h o n d r o s a r c o m a and periosteal o s t e o s a r c o m a is important since these lesions have different p r o g n o ses and treatment options. Periosteal o s t e o s a r c o m a is often treated with wide resection. In U n n i ' s series [11, 4 out of the 23 patients died o f metastasis. Other authors have reported a similar p r o g n o s i s for periosteal ost e o s a r c o m a . Hall et al. [7] r e p o r t e d that 10 out o f 61 patients with periosteal o s t e o s a r c o m a died o f metastatic disease. In B e r t o n i ' s series [811, the

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g r o u p with periosteal o s t e o s a r c o m a s was treated with either marginal excision, w i d e surgical excision, or a m putation and had a 15% incidence o f metastases. In contrast, similar treatm e n t of patients with periosteal c h o n d r o s a r c o m a s was usually effective and metastases were very uncommon. T h e septal pattern o f e n h a n c e m e n t following gadolinium-DTPA administration is due to the lobular pattern o f growth o f the c a r t i l a g i n o u s c o m ponent o f the tumor. It is not d i a g nostic o f any entity and can be seen in o s t e o s a r c o m a s with a large cartilaginous c o m p o n e n t as well as in purely c h o n d r o i d lesions. The diagnosis in this case was s u g g e s t e d on the routine radiographs. T h e extent o f the lesion and the a b s e n c e o f int r a m e d u l l a r y involvement was well d e p i c t e d on MRI, and the g a d o l i n i u m - e n h a n c e d i m a g e s c o n f i r m e d that there was a large cartilaginous c o m ponent to the periosteal o s t e o s a r c o ma.

Acknowledgements. The authors would like to thank Dr. K.K, Unni of the Mayo Clinic for his review of the slides and helpful comments.

References 1. Unni KK, Dahlin DC, Neanpit JW. Periosteal osteogenic sarcoma. Cancer 1976; 7: 2476. 2. Aoki J, Sone S, et al. MR of enchondroma and chondrosarcoma: rings and arcs of Gd-DTPA enhancement. J Comput Assist Tomogr 1991; 15: 1011. 3. Geirnaerdt MJA, et al. Cartilaginous tumors: correlation of gadolinium-enhanced MR imaging and histopathologic findings. Radiology 1993; 186: 813-817. 4. Varma DGK, Ayala AG, Carrasco CH, Guo S, Kumar R, Edeiken J. Chondrosarcoma: MR imaging with pathologic correlation. Radiographics 1992; 12: 687. 5. l,loyd GAS, Ohelps PD, Michaels L. The imaging characteristics of naso-sinus chondrosarcoma. Clin Radiol 1992; 46:189-192. 6. Schajowicz F, McGuire M, et al. Osteosarcomas arising on the surfaces of long bones. J Bone Joint Surg [Am] 1988; 70: 555. 7. Hall RB, et al. Periosteal osteosarcoma. Cancer 1985; 55: 165-171. 8. Bertoni F, et al. Periosteal chondrosarcoma and periosteal osteosarcoma: two distinct entities. J Bone Joint Surg ]Br] 1982; 64:70 376.