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research-article2014

IJSXXX10.1177/1066896914540937International Journal of Surgical Pathology XX(X)Jain et al

Case Report

Soft Tissue Giant Cell Tumor of Low Malignant Potential of Mediastinum: A Rare Case Report

International Journal of Surgical Pathology 2015, Vol. 23(1) 71­–74 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1066896914540937 ijs.sagepub.com

Deepali Jain, MD1, Sudheer Arava, MD1, Biplab Mishra, MS1, Sanjay Sharma, MD1, Raju Sharma, MD1, and Rajinder Parshad, MS1

Abstract Giant cell tumor (GCT) is primarily a bone neoplasm. Rare origin of the tumor from soft tissues has been reported. Involvement of mediastinum by GCT is even rarer. We herein describe an interesting case of huge mediastinal tumor in a young man. Radiologically, no primary osseous lesion was present throughout the body. Morphologically, tumor resembles osseous GCT with increased mitotic activity. Hence, the case was diagnosed as soft tissue GCT of low malignant potential at the rare site of mediastinum. To the best of our knowledge, the present case is the fourth reported case. Pathologists and clinicians need to be aware of the rare diagnosis of GCT in mediastinum and should carefully evaluate the clinical and radiological findings. Keywords giant cell tumor, GCT, mediastinum, soft tissue

Introduction Giant cell tumor (GCT) has not been described as a common mediastinal tumor except for secondary involvement by spinal GCT, which itself is an uncommon site of osseous GCT.1 Primary mediastinal GCT has been reported twice in the literature of 3 different cases (Table 1).2,3 It broadly encompasses GCT of soft tissue without any osseous origin. Imaging plays an important role in deciphering the exact origin of the tumor in the mediastinum in reference to different compartments, lung, pleura, chest wall ribs, or spinal vertebrae. However histomorphology and clinical outcome remain same whether the tumor arises from bone or soft tissue. In this report, we discuss a rare case of large mediastinal tumor that on histology displayed characteristic features of GCT.

Case A 28-year-old nonsmoker male presented with complaints of mild dull aching pain on the left side of chest for 4 months. There was no cough, hemoptysis, dyspnea, or any constitutional symptoms. A chest X-ray showed a well demarcated mass lesion involving the left hemithorax (Figure 1A). A contrast-enhanced computed tomography (CECT) of the thorax revealed a large heterogeneous mediastinal mass on the left side measuring 9 cm × 11 cm

× 11 cm extending from thoracic/dorsal vertebrae D1 to D5. Pressure erosions on body of D3 vertebra and adjoining posterior rib were visualized. Moderate pleural effusion was also noticed on the left side (Figure 1B) for which a left-sided chest tube was inserted in a different hospital. Subsequent CECT did not reveal any significant pleural effusion. Whole body bone scan (Tc-99m-MDP bone scintigraphy) showed a mildly increased radiotracer uptake in the posterior end of left third rib, suggestive of local infiltration by the tumor. No distant skeletal metastases were seen. Serum calcium was within normal limits. Serum α-fetoprotein and β-human chorionic gonadotrophin levels were not elevated. A radiological diagnosis of neurogenic tumor was given due to predominant involvement of posterior mediastinum. An ultrasonography-guided trucut biopsy of the tumor was performed. Histologic examination showed a tumor of dual population of cells including mononuclear and multinucleated giant cells. Frequent mitotic figures were 1

All India Institute of Medical Sciences, New Delhi, India

Corresponding Author: Deepali Jain, Department of Pathology, All India Institute of Medical Sciences, New Delhi 110029, India. Email: [email protected]

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Table 1.  Summary of Clinicopathological Features of Mediastinal GCT in the Literature. Source and Year

Age/Gender

Fu et al (2002)2 31/Female



18/Male

Goldberg et al 53/Male (2009)3 Present case

28/Male

Symptoms

Location

Necrosis and Bone Involvement Tumor Size Hemorrhage

None Radiating pain and Posterior mediastinum paraesthesia to upper limb None Incidental finding Posterior mediastinum on routine X-ray Anterior chest Posterior Pressure erosion pain mediastinum and sclerosis fifth rib Chest pain Posterior Pressure erosions mediastinum of dorsal third (D3) vertebra and third rib

Mitotic Rate; Ki-67

Outcome, Treatment Follow-up

Recurrence

8.0 cm

NA

Less than 5%

Resection

Alive, 6 months

No

2.5 cm

Absent

Less than 5%

Resection

Alive, 108 months

No

13 cm

Present

No increase

Resection

Alive

No

15 cm

Present

High, 20% to 30%

Debulking

Alive, 5 months

No

Abbreviations: GCT, giant cell tumor; NA, not applicable.

Figure 1.  (A) Plain chest radiograph. (B) Axial thoracic contrast computed tomography image. A large upper mediastinal mass on the left with left pleural effusion (A). The mass shows multiple necrotic areas and destruction of posterior end of the third rib (B, yellow arrow).

recognized. The features were consistent with the diagnosis of GCT. At this point of time clinicians and radiologists were asked for radiology review and skeletal survey of the patient to detect any primary lytic lesion in the bone. However, there was no lytic lesion in the bone anywhere in the body except for pressure erosions of the D3 vertebra and third rib by the tumor. Intraoperatively, the tumor was large, measuring 15 cm × 12 cm × 12 cm, involving almost the whole of the left upper hemithorax; highly vascular and densely adherent to left chest wall, left upper lobe of lung, and mediastinal

structures. The upper lobe of the lung was displaced and compressed downwards. Due to profuse bleeding and dense adhesions, the tumor could only be debulked. Some residual tumor tissue at the apical region of left lung and around the capsule was left behind. Gross examination of the tumor showed multiple pieces of tan brown tumor tissue; the largest one measuring 15 cm × 10 cm × 8 cm. The tumor was variegated in appearance, punctuated by variably spaced cystic cavities filled with old and fresh hemorrhage and areas of necrosis (Figure 2A). Histology revealed a tumor with geographic hemorrhagic necrosis and aneurysmal bone cyst–like areas. The

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Figure 2.  (A) Grossly variegated tan brown tumor that is variably spaced by cystic cavities filled with blood and areas of necrosis. (B) Photomicrograph shows dual population of cells including mononuclear stromal cells and multinucleated osteoclast-like giant cells (hematoxylin–eosin, 400×). (C) SMA shows cytoplasmic positivity. (D) MIB-1 labeling index is high.

latter were nonendothelialized cystic spaces filled with fresh blood and walled off by vascularized fibrous tissue. The tumor cells were ovoid to spindle in shape and showed frequent mitotic activity (12 per 10 high power fields). Notably there was no nuclear atypia. The tumor cells were admixed with giant cells and both of these cellular components were embedded in richly vascularized fibroconnective tissue (Figure 2B). Osteoid was also recognized amid tumor cells focally.

Immunohistochemistry Cells were positive for smooth muscle actin and vimentin (Figure 2C). Giant cells were reactive with CD 68 immunostain. Increased vascularity of the tumor was highlighted by CD-34 immunostain. MIB-1 labeling index was high,

ranging from 20% to 30% (Figure 2D). Thus, the final diagnosis of soft tissue GCT of low malignant potential arising at mediastinum was rendered.

Discussion Soft tissue GCTs were first described as benign tumors.4 Later Folpe et al proposed the term giant cell tumors of low malignant potential in the face of frequent clinical recurrence and unknown metastatic potential and regarded these as the soft tissue analogue of GCT of bone.5 The most important radiological and histological differential diagnosis of GCT seen in mediastinum is either spinal or chest wall GCT. Radiographic imaging plays an important role to rule out the possibility of GCT of either the vertebra or rib, which may be extending into the soft

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tissue of the mediastinum. There are case reports where spinal GCT presented as large mediastinal tumor; however, on radiology complete collapse and destruction of vertebra was evident opposed to pressure erosion or secondary impingement of the slowly growing mediastinal tumor. Second, single bone involvement hints more toward primary spinal or osseous GCT, whereas multiple bones are affected in secondary involvement.1 In the present case there was involvement of body of D3 vertebra and posterior third rib, which appeared secondarily involved by the huge mediastinal tumor. Whether a tumor is of bone or soft tissue origin, it has no bearing on morphologic appearance of the tumor. These tumors may show frequent mitotic activity ranging from none to more than 30 per 10 high power fields and vascular invasion. Significant nuclear atypia should be absent to distinguish these from either giant cell rich sarcomas or malignant GCT. Like its bony counterpart, soft tissue GCTs run a benign clinical course but have potential for recurrence and metastasis.4 Although histology per se does not predict the clinical course of the tumor, high grade or frankly malignant sarcomas have bad prognosis.4,5 The exact pathogenesis of GCT is unknown though origin from undifferentiated mesenchymal cells has been proposed.6 Soft tissue GCTs usually affect lower extremities.4,5 Mediastinum is a rarely reported site for soft tissue GCT. Three cases reported earlier of mediastinal GCT presented as posterior mediastinal tumors.2,3 Morphologically all 3 were similar to the present case except for increase mitotic activity in the index case. No recurrence was noticed although in one case follow-up was only of 6 months and in one case the follow-up period was not mentioned. Tumors were completely excised in all 3 cases. In contrast, chances of recurrence in our case are high as the tumor could be incompletely excised owing to high vascularity and adherence of the tumor to vital structures. The patient is currently on follow-up and an adjuvant therapy is planned to be given.

Conclusion The occurrence of GCT in mediastinal soft tissue is a challenge to the clinician, radiologist, and pathologist. The most important issue is to clearly delineate the origin of the tumor radiologically. Subsequently on histology it becomes imperative to distinguish these tumors correctly from much more common mediastinal neoplasms and close morphology mimics. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.

References 1. Sakurai H, Mitsuhashi N, Hayakawa K, Niibe H. Giant cell tumor of the thoracic spine simulating mediastinal neoplasm. AJNR Am J Neuroradiol. 1999;20:1723-1726. 2. Fu K, Moran CA, Suster S. Primary mediastinal giant cell tumors: a clinicopathologic and immunohistochemical study of two cases. Ann Diagn Pathol. 2002;6:100-105. 3. Goldberg J, Azizad S, Bandovic J, Khan A. Primary mediastinal giant cell tumor. Rare Tumors. 2009;1(2):e45. 4. Salm R, Sissons AH. Giant-cell tumours of soft tissues. J Pathol. 1972;107:27-39. 5. Folpe AL, Morris RJ, Weiss SW. Soft tissue giant cell tumor of low malignant potential: a proposal for reclassification of malignant giant cell tumor of soft parts. Mod Pathol. 1999;12:894-902. 6. Raskin KA, Schwab JH, Mankin HJ, Springfield DS, Hornicek FJ. Giant cell tumor of bone. J Am Acad Orthop Surg. 2013;21:118-126.

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Soft tissue giant cell tumor of low malignant potential of mediastinum: a rare case report.

Giant cell tumor (GCT) is primarily a bone neoplasm. Rare origin of the tumor from soft tissues has been reported. Involvement of mediastinum by GCT i...
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