Clear cell chondrosarcoma proximal femur with secondary aneurysmal component - A rarity.

Abstract

Clear cell chondrosarcoma is a rare benign tumor constituting to about 2–4% of all chondrosarcoma. It was first described by Unni et al. in 19761Unni K.K. Dahlin D.C. Beabout J.W. Sim F.H. Chondrosarcoma: clear cell variant. A report of sixteen cases.J Bone Joint Surg Am. 1976; 58: 676-683Crossref PubMed Scopus (133) Google Scholar Common sites of occurrence are epiphyseo metaphyseal regions of femur, proximal humerus and proximal tibia. This tumor clinico radiologically is frequently misdiagnosed as benign lesion such as giant cell tumor, aneurysmal bone cyst, chondroblastoma & osteoblastoma. Conservative surgeries like curettage will lead to local recurrences, excision of the lesion & reconstruction is the treatment of choice. Despite low malignant potential, recurrence & metastasis have been reported. A woman aged 55years attended orthopedic outpatient department with complaints of pain in right hip since 2 years. To start with symptoms were of mild to moderate grade. For past three months symptoms got aggravated hindering daily activities. There was no history of trauma, fever or massages. No history of steroid intake or contact history of TB. Examination revealed mild fullness in right groin with a tender hip anteriorly. Movements were grossly restricted concentrically and were painful. No other joint involvement was appreciated. With clinical suspicion of avascular necrosis with secondary osteoarthritis, patient was further evaluated. Routine investigations were within normal limits. She was diagnosed as diabetic on admission. Alkaline phosphatase & Calcium levels were within normal range. Patient had normal lipidemic levels and negative sickling test. Abdominal Sonography revealed no organomegaly. Radiographs revealed multiple cystic areas with mild sclerosis in right femur head with expansile lytic lesion in neck extending into intertrochanteric region obliterating head & neck offset. No matrix calcification (Fig. 1). BONE SCAN revealed increased uptake in right head & neck femur with no evidence of increased uptake in other parts of skeleton. CT revealed mildly expansile lytic lesion in head & neck femur with clear borders. No matrix calcification (Fig. 2). MRI revealed low signal intensity in TI Weighted images, moderately bright signals in T2 Weighted images. No soft tissue involvement (Fig. 3). As none of the radiological investigations were confirmatory, patient was subjected to FNAC. FNAC under fluoroscopic guidance revealed features suggestive of Aneurysmal Bone Cyst. The lesion being juxtaarticular with no cortical breach or soft tissue involvement patient was planned for excision and hemiarthroplasty. Intra operatively there was no evidence of pathological fracture or soft tissue extension, head & neck ballooning was seen. Intact head was dislocated and excision of head and neck was done 1 cm proximal to the lesion. Proximal femur was replaced with HA coated modular bipolar stem. Excised specimen was sent for Histopathological examination. Postoperative period was uneventful .Sutures were removed on 10th postoperative day and gradual weight bearing was started with walker. Later walking without aid was permitted by 6th post-operative week. At recent follow up of 1 year, patient was walking without support and pain. Gait patterns were normal, no limb length discrepancy and hip range of movements were near normal. Cytology of sections showed lobules of low grade mesenchymal tumor cells composed of large, round cells with clear cytoplasm & centrally placed nuclei. Tumor lobules exhibit few small cystic spaces surrounded by multinucleate giant cells. In centre of lobules, spicules of calcification present. There are areas resembling ABC. Histopathological report was opined as clear cell chondrosarcoma with Aneurysmal Bone Cyst like component (Fig. 4). Clear cell chondrosarcoma is a rare low grade malignant tumor that was first described by Unni et al. in 19761Unni K.K. Dahlin D.C. Beabout J.W. Sim F.H. Chondrosarcoma: clear cell variant. A report of sixteen cases.J Bone Joint Surg Am. 1976; 58: 676-683Crossref PubMed Scopus (133) Google Scholar. It has an incidence of 2–4%2Greenspan A. Tumours of cartilage origin.Orthop Clin North Am. 1989; 20: 347-366PubMed Google Scholar more so is the rarity when associated with ABC like components.3Tay Timothy Wong Steven Bak Siew Clear cell chondrosarcoma with secondary aneurysmal bone cyst changes.Singapore Med J. 2014; 55: e49-e51Crossref PubMed Scopus (8) Google Scholar It usually occurs in 3rd to 5th decade of life.4Bjornsson J. Unni K.K. Dahlin D.C. Beabout J.W. Sim F.H. Clear cell chondrosarcoma of bone: observations in 47 cases.Am J Surg Pathol. 1984; 8: 223-230Crossref PubMed Scopus (134) Google Scholar Commonly seen in third to fifth decade of life. Males are affected twice as common as females. Most of these tumors occur in epiphyseo metaphyseal region of long bones such as femur, tibia and proximal humerus. Other rare sites include skull, spine, pelvis, phalanges, and larynx.5Laitinen Minna Nieminen Jyrki Pakarinen Toni-Karri An unusual case of clear cell chondrosarcoma with very late recurrence and lung metastases, 29 years after primary surgery.Case Reports in Orthopedics. 2014; (Article ID 109569, 6 pages)PubMed Google Scholar Radiologically these tumors appear as expansile, radiolucent lesions in epiphyseo metaphyseal region with intact cortices.6Le Charpentier Yves Forest Michel Postel Michel Tomeno Bernard Abelanet Rene Clear Cell Chondrosarcoma: a Report of five cases including ultrastructural study.Cancer. 1979; 44: 622-629Crossref PubMed Scopus (45) Google Scholar No periosteal new bone formation or matrix calcification is seen. Cartilage tumors generally exhibit matrix calcification in the form of rings or popcorn shape, clear cell chondrosarcoma is an exception. Diaphysis is rarely involved7Kang Chang Min Han Chung Soo Jung Gwang Young Jeong Ho Yeon Kim Young Jun J Korean Bone Joint Tumor Soc. 2014; 20: 89-93Crossref Google Scholar. These nonspecific features commonly lead to misdiagnosis of benign lesions such as Aneurysmal Bone Cyst, chondroblastoma, Giant Cell Tumor, osteoblastoma. Even though clear cell chondrosarcoma resembles chondroblastoma microscopical presence of clear cells make them unique. Most of the clear cells on electron microscopy show irregular shaped nuclei with indentations. Large dilated endoplasmic reticulum cisternae, bundles of actin like filaments & a few glycogen particles.6Le Charpentier Yves Forest Michel Postel Michel Tomeno Bernard Abelanet Rene Clear Cell Chondrosarcoma: a Report of five cases including ultrastructural study.Cancer. 1979; 44: 622-629Crossref PubMed Scopus (45) Google Scholar Confusion with osteoblastic neoplasms may be clarified on electron microscopy by showing that cells lining the bony spicules are not part of the neoplastic process but rather are the result of stromal reaction.2Greenspan A. Tumours of cartilage origin.Orthop Clin North Am. 1989; 20: 347-366PubMed Google Scholar Presence of clear cells is the primary differentiating feature between giant cell tumor/aneurysmal bone cyst and clear cell chondrosarcoma.2Greenspan A. Tumours of cartilage origin.Orthop Clin North Am. 1989; 20: 347-366PubMed Google Scholar Rarely aneurysmal bone cyst like features radiologically and microscopically may co exist with clear cell chondrosarcoma as seen in our case, these features depend on the phase of presentation.3Tay Timothy Wong Steven Bak Siew Clear cell chondrosarcoma with secondary aneurysmal bone cyst changes.Singapore Med J. 2014; 55: e49-e51Crossref PubMed Scopus (8) Google Scholar Serum calcium, phosphorus will generally be within normal range. Alkaline phosphatase may be within normal range or elevated. Elevated levels of Alkaline phosphatase on follow up is a warning sign signifying recurrences or metastasis.8Donati D. Yin J.Q. Colangeli M. et al.Clear cell chondrosarcoma of bone: long time follow-up of 18 cases.Arch Orthop Trauma Surg. 2008; 128: 137-142Crossref PubMed Scopus (40) Google Scholar Recurrences as late as 29 years post excision of primary lesion has been reported.5Laitinen Minna Nieminen Jyrki Pakarinen Toni-Karri An unusual case of clear cell chondrosarcoma with very late recurrence and lung metastases, 29 years after primary surgery.Case Reports in Orthopedics. 2014; (Article ID 109569, 6 pages)PubMed Google Scholar Our case was followed up to 1 year and we observed no local recurrence or distant metastasis Histologically clear cell chondrosarcoma exhibit lobules of cells with clear cytoplasm. Well defined cytoplasmic borders and central round nuclei with vesicular chromatin. Benign osteoclast like giant cells may be seen at periphery. Fine lines of calcification, osteoid or bone formation may be found scattered among tumor cells. Chondroid matrix may also be present.3Tay Timothy Wong Steven Bak Siew Clear cell chondrosarcoma with secondary aneurysmal bone cyst changes.Singapore Med J. 2014; 55: e49-e51Crossref PubMed Scopus (8) Google Scholar, 9Masui F. Ushigome S. Fujii K. Clear cell chondrosarcoma: a pathological and immunohistochemical study.Histopathology. 1999; 34: p 447-52Crossref Scopus (28) Google Scholar Despite the presence of a low malignant potential these tumors are not to be treated by curettage and grafting as it has a high recurrence rate. Wide excision and reconstruction is the treatment of choice. Other options include en bloc resection including a margin of normal bone. In conclusion clear cell chondrosarcoma is a rare low grade malignant bone tumor occurring in epiphyseo metaphyseal region. Radiological features mimic a giant cell tumor, aneurysmal bone cyst, chondroblastoma & osteoblastoma. To prevent confusion in diagnosis cytopathology should always be considered in every case. Though low grade malignant, these tumors are to be treated by radical excision and reconstruction to prevent recurrences. Patients are to be regularly followed periodically as recurrences and metastasis may occur at a later date.