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Year : 2018  |  Volume : 61  |  Issue : 2  |  Page : 245-247
Clear cell sarcoma arising from paraspinal ligament of thoracic spine: Report of an unusual case

1 Department of Pathology, Rohilkhand Medical College and Hospital, Bareilly, Uttar Pradesh, India
2 Department of Pathology, Command Hospital, Kolkata, West Bengal, India
3 Department of Surgery, Rohilkhand Medical College and Hospital, Bareilly, Uttar Pradesh, India

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Date of Web Publication20-Apr-2018


Clear cell sarcoma (CCS) is an unusual but aggressive soft-tissue tumor with an incidence of <1% of all soft-tissue sarcomas. It was previously termed “malignant melanoma of soft parts” due to its resemblance clinically and morphologically. Normally CCS is seen in patients aged 20–40 years. A rare case of CCS of paraspinal ligament in a 5-year-old boy is being reported. Histopathology and immunohistochemistry markers confirmed the diagnosis. The present case is unique since the entity itself is rare and also due to its occurrence in a child.

Keywords: Clear cell sarcoma, melanoma, paraspinal ligament, soft tissue

How to cite this article:
Agrawal R, Deb P, Sharan J, Kumar P. Clear cell sarcoma arising from paraspinal ligament of thoracic spine: Report of an unusual case. Indian J Pathol Microbiol 2018;61:245-7

How to cite this URL:
Agrawal R, Deb P, Sharan J, Kumar P. Clear cell sarcoma arising from paraspinal ligament of thoracic spine: Report of an unusual case. Indian J Pathol Microbiol [serial online] 2018 [cited 2023 Jun 9];61:245-7. Available from:

   Introduction Top

Clear cell sarcoma (CCS) was first described by Enzinger in 1965. It is a rare, aggressive, soft-tissue tumor constituting approximately 1% of all soft-tissue sarcomas. Due to its close clinical and histological similarity with malignant melanoma, Chung and Enzinger proposed the name “malignant melanoma of soft parts.”[1]

It is known to occur mainly in the soft tissues and dermis.[2] CCS of tendons and aponeuroses is a rare, high-grade malignant soft-tissue tumor.

   Case Report Top

A 5-year-old boy presented with swelling over the left back for 1 month. The swelling was sudden in onset and gradually progressive in nature. It was very tender and was located 5 cm lateral to the thoracic spine. There was no history of fever. The pain subsided on taking medication. His hematological, coagulation, and biochemical profiles were within normal limits. On examination, the swelling measured 6 cm × 6 cm, was tender and immobile. Clinically, it was diagnosed as an abscess. X-ray revealed a soft-tissue mass with normal underlying bone. Ultrasonography showed a subcutaneous heterogenous collection with internal echoes. Pus was seen in the in the paraspinal ligament of paravertebral region. Peroperatively, it turned out to be solid, giving a clinical impression of sarcoma. Hematoxylin and eosin (H and E)-stained sections of the excised tissue showed the absence of an epithelial covering [Figure 1]a. Clusters of fusiform cells [Figure 1]b were present that were separated by a thin fibrovascular septa [Figure 1]c. The individual cells were large with pleomorphic, vesicular nuclei, prominent 1–2 basophilic nucleoli, and clear cytoplasm [Figure 1]d. Mitoses were frequent, approximately 2–3/10 hpf. Apoptotic bodies and areas of necrosis were observed. Few multinucleated giant cells were present. However, no obvious pigmentation could be identified.
Figure 1: Microphotograph showing (a) Compact arrangement of cells (H and E, ×40) (b) fusiform cells with clear cytoplasm (H and E, ×100) (c) nests of cells separated by fibrovascular strands (H and E,×100) (d) cells with clear cytoplasm, vesicular nuclei, and no mitotic figure (H and E, ×400)

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Immunohistochemistry (IHC) revealed positivity for pancytokeratin [Figure 2]a, epithelial membrane antigen [Figure 2]b, vimentin [Figure 2]c, and melan A [Figure 2]d, with focal immunopositivity for HMB 45 [Figure 2]e; while chromogranin, synaptophysin, S-100 protein, desmin, and smooth muscle antigen were immunonegative. Staining for Ki67 showed a proliferation index of around 70% [Figure 2]f. Based on the histological and immunohistochemical profile, a diagnosis of CCS was offered.
Figure 2: Immunohistochemistry markers showing (a) cytokeratin positivity (×100) (b) epithelial membrane antigen focal positivity (×100) (c) Vimentin positivity (×100) (d) Melan A focal positivity (×100) (e) HMB 45 positivity (×100) (f) Ki 67 index (×100)

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   Discussion Top

An extensive review of literature revealed that the index case was the third case of CCS located in the paraspinal ligament and the fifth affecting the thoracic region.[3]

CCS, albeit rare, is generally known to affect the extremities, especially foot and ankle, followed by knee, thigh, and hand.[4] Rare sites of involvement include pleura, chest wall, spinal nerve roots, scapula, retroperitoneum, buttock, and mediastinum.[5],[6] Rarely cases involving kidney, trunk, penis, gastrointestinal tract, and head and neck have also been reported.[7]

Majority of the cases of CCS have been observed in the 20–40 age group, with mean age of 27 years [3] and having a predilection for female patients. In this regards, the present case was unique because it presented in a young male child. It originates from tendons, aponeuroses, and fascial structures of the extremities with a predilection for the feet and knees. CCS presents as an insidiously growing lump or hard mass causing pain or tenderness.

CCS is characterized by a recurrent chromosomal translocation t (12; 22), which results in fusion of the EWS gene on 22q with the ATF1 gene on 12q.[8] It has been associated with both EWSR1-ATF1 and EWSR1-CREB1 fusion transcripts.[9] The exact histogenesis remains obscure, but the presence of intracellular melanin in two-third of the cases supports origin from migrated cells of neural crest.[3],[9] For this reason, the term malignant melanoma of soft part seems preferable over the purely descriptive term of CCS. The reciprocal translocation t (12; 22) (q13; q12) is observed in more than 90% of CCS cases along with polysomy of chromosome 8 as a secondary abnormality in many cases.[8],[9]

Differentiation of CCS from other close differentials often requires correlation with clinical, histological, and molecular findings. Main differentials include tumors such as metastatic malignant melanoma, malignant cellular blue nevus, malignant peripheral nerve sheath tumor, paraganglioma-like dermal melanocytic tumors and nonmelanotic tumors such as perivascular epithelioid cell tumor (PEComas), epithelioid leiomyosarcoma, fibrosarcoma, alveolar soft-part sarcoma, monophasic synovial sarcoma, and renal cell carcinoma.[1],[10]

CCS can involve any ligament, tendon, or aponeurosis. Thus, radiological and histopathological evaluation aided by an appropriate panel of IHC markers is imperative for proper diagnosis. Because of their typical histologic picture and their particular clinical behavior, they should be regarded as a definite clinicopathological entity. Imaging studies such as X-rays, computed tomography (CT) scans or magnetic resonance imaging (MRI) may be required for diagnosis. Chest CT, bone scan, and positron emission tomography are often required to assess metastases. MRI typically shows a benign-looking, well-defined, homogenous mass; on T1-weighted MR images, it is usually homogeneous and isointense or slight hyperintense to muscles, whereas on T2-weighted MR images, it is usually more heterogeneous with variable signal intensity.[4]

Diagnosis of CCS can be challenging. Histologically, it shows compact nests or fascicles of predominantly fusiform or spindled cells with a clear to granular cytoplasm surrounded by a delicate framework of fibrocollagenous tissue contiguous with the adjacent tendons or aponeuroses. The cells have highly distinctive features consisting of vesicular nuclei and prominent basophilic nucleoli reminiscent of malignant melanoma.[1] The histologic features of cellular arrangement in nest, cluster or “ball”-like formations and a prominent nucleolus are the most reliable diagnostic patterns. The cytoplasm varies from being clear to weakly eosinophilic and contains a large amount of intracellular glycogen giving it the clear cell appearance. More than 50% of case contains multinucleate (wreath-type) giant cells. Approximately, two-thirds of the tumors contain a variable amount of melanin pigment demonstrable on H and E or, using special stains. The cells show absent or minimal pleomorphism and very few mitotic figures indicating its slow-growing nature. Areas of necrosis may be present. CCS such as melanoma, shows immunopositivity for S-100, HMB-45, and microphthalmia transcription factor.

Tumor size more than 5 cm and necrosis are indicators of poor prognosis. Age, location, depth, or proliferation index are independent prognostic factors. Metastasis occurs in more than half of the cases and usually to the bones, lymph node, and lungs with 5-year survival rates of 50%–65%.[3] Recurrence is a common feature.[2]

Treatment depends on the site and the extent of the disease. Radical surgery is the mainstay of therapy with chemotherapy used in metastasis. Use of standard sarcoma regimens has not been successful, while interferon-alpha 2 B has been reported to have some role.[10]

   Conclusion Top

CCS should be considered in the differential diagnosis of paraspinal masses. Confirmed diagnosis requires histopathology and IHC marker panel. Complete surgical excision with radiotherapy is the mainstay of treatment.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Chung EB, Enzinger FM. Malignant melanoma of soft parts. A reassessment of clear cell sarcoma. Am J Surg Pathol 1983;7:405-13.  Back to cited text no. 1
Malchau SS, Hayden J, Hornicek F, Mankin HJ. Clear cell sarcoma of soft tissues. J Surg Oncol 2007;95:519-22.  Back to cited text no. 2
Gollard R, Hussong J, Bledsoe J, Rosen L, Anson J. Clear cell sarcoma originating in a paraspinous tendon: Case report and literature review. Acta Oncol 2008;47:1593-5.  Back to cited text no. 3
De Beuckeleer LH, De Schepper AM, Vandevenne JE, Bloem JL, Davies AM, Oudkerk M, et al. MR imaging of clear cell sarcoma (malignant melanoma of the soft parts): A multicenter correlative MRI-pathology study of 21 cases and literature review. Skeletal Radiol 2000;29:187-95.  Back to cited text no. 4
Bury T, Hermans G, Alexis-Agnant R, Chevalier P, Limet R, Bartsch P, et al. Clear cell sarcoma: An extremely rare cause of pleural disease. Eur Respir J 1997;10:2653-6.  Back to cited text no. 5
Kazakos CJ, Galanis VG, Giatromanolaki A, Verettas DA, Sivridis E. Clear cell sarcoma of the scapula. A case report and review of the literature. World J Surg Oncol 2006;4:48.  Back to cited text no. 6
Dim DC, Cooley LD, Miranda RN. Clear cell sarcoma of tendons and aponeuroses: A review. Arch Pathol Lab Med 2007;131:152-6.  Back to cited text no. 7
Fujimura Y, Ohno T, Siddique H, Lee L, Rao VN, Reddy ES, et al. The EWS-ATF-1 gene involved in malignant melanoma of soft parts with t(12;22) chromosome translocation, encodes a constitutive transcriptional activator. Oncogene 1996;12:159-67.  Back to cited text no. 8
Hisaoka M, Ishida T, Kuo TT, Matsuyama A, Imamura T, Nishida K, et al. Clear cell sarcoma of soft tissue: A clinicopathologic, immunohistochemical, and molecular analysis of 33 cases. Am J Surg Pathol 2008;32:452-60.  Back to cited text no. 9
Mavrogenis A, Bianchi G, Stavropoulos N, Papagelopoulos P, Ruggieri P. Clinicopathological features, diagnosis and treatment of clear cell sarcoma/melanoma of soft parts. Hippokratia 2013;17:298-302.  Back to cited text no. 10

Correspondence Address:
Ranjan Agrawal
Department of Pathology, Rohilkhand Medical College Hospital, Pilibhit Bypass Road, Bareilly, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_516_17

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