Giant cell tumor of soft tissue: A case report

Abstract

Introduction and importance

Giant cell tumor of soft tissue (GCT-ST) is a rare primary neoplasm of soft tissues. It usually involves superficial and deeper soft tissues of upper and lower extremities, followed by trunk.

Case presentation

A 28-year-old female, presented with a painful mass in left abdominal wall for three months. On examination, it measured 4 × 4 cm with ill-defined margins. CECT showed ill-defined enhancing lesion deep to muscle planes with possible invasion of peritoneal layer. Histopathology showed multinodular architecture with intervening fibrous septa and metaplastic bony tissue encasing the tumor. Tumor composed of round to oval mononuclear cells and osteoclast like multinucleated giant cells. Mitotic figures were eight per hpf. A diagnosis GCT-ST of anterior abdominal wall was made. Patient was treated with surgery followed by adjuvant radiotherapy. Patient is disease free at one year follow up.

Clinical discussion

These tumors mostly involve extremities and trunk and usually presents as a painless mass. Clinical features depend upon the exact location of the tumor. Common differential diagnosis includes tenosynovial giant cell tumors and malignant giant cell tumors of soft tissue and GCT of Bone.

Conclusion

Diagnosis of GCT-ST is difficult on cytopathology and radiology alone. Histopathological diagnosis should be done to rule out the malignant lesions. Complete surgical resection with clear resection margins is the mainstay of treatment. Adjuvant radiotherapy should be considered in case of incomplete resection. Long follow-up is necessary for these tumors as local recurrence and risk of metastasis cannot be predicted.

Highlights

• •GCT-ST of anterior abdominal wall is a rare entity.
• •Complete surgical resection with clear resection margins is the mainstay of treatment.
• •Adjuvant radiotherapy should be considered in case of incomplete resection.
• •For superficial tumors electron beam therapy is a clinically feasible option.

1. Introduction

Giant cell tumor of soft tissue (GCT-ST) is a rare primary neoplasm of soft tissues. [1]. It usually involves superficial and deeper soft tissues of upper and lower extremities. [2] However, case reports of lesion in trunk, head and neck region, breast, colon and liver represent unusual location of this tumor. [3], [4], [5], [6]

This lesion was first described in 1972 by two simultaneous publications by Salm and Sissons and Guccion and Enzinger. [7], [8] Salm et al. [7] reported a series of 10 cases, and considered these as mostly benign soft tissue neoplasms that were histologically similar to the giant cell tumor of bone. Guccion et al. [8] reported a series of 32 cases showing a more aggressive behaviour, and labelled it as Malignant giant cell tumor of soft parts. Additional reports also emphasized towards the atypical appearance and malignant behaviour of these lesions and the term Giant cell tumor of soft tissue was accepted to be synonymous with “malignant fibrous histiocytoma, giant cell rich” for many years.

Nascimento et al. reported 10 cases having histologic features similar to the tumor description given in case series by Salm and Sissons, and he labelled it as “giant cell tumor of soft parts”. Two of the patients were found to have lung metastatis and died, and it was considered a low-grade sarcoma.

Later, in a case series of 31 cases, Folpe et al. [9] described similar lesions, but without marked cellular atypia and this was labelled as “giant cell tumor of low malignant potential”. Two more case series by O'Connell et al. and Oliveira et al. [10], [11] reported similar findings and considered these to behave as benign tumors if completely excised.

Lee et al. [12] analysed the genotypes of H3F3A and other histone H3 genes in 15 cases of GCT-ST and found that GCT-ST lacks the mutations of the H3F3A gene that are present in most giant cell tumors of bone, suggesting a different pathogenesis.

We report a case of GCT-ST arising in the abdominal wall admitted in a tertiary care teaching hospital with its detailed clinical, radiological, cytological, and histopathological findings, and treatment and follow up details. This case is reported in line with the SCARE criteria. [13]

2. Presentation of case

2.1. Clinical details

Twenty-eight-year-old lady, presented to the hospital with swelling over left upper abdomen for three months. It was associated with local, non-radiating pain without any functional limitation. On examination, her performance status was ECOG 1. On examination, there was a swelling (4 × 4 cm) in left hypochondrium with ill-defined margins, smooth surface globular shape, and cystic consistency. There was mild tenderness over the swelling. Ultrasonography of abdomen revealed hypoechoic lesion of approximately 1.5 cm size in abdominal wall at left periumbilical location; No Intra-abdominal extension was noted.

2.2. Radiology

CECT abdomen showed 19 × 15 mm ill-defined enhancing mass lesion in ventral abdominal wall in left upper abdomen deep to muscle planes with possible invasion of peritoneal layer. No evidence of any organ involvement noted. MRI showed evidence of hyper intense nodular lesion of size 19 × 18 mm in the left anterior abdominal wall posterior to muscle layer and anterior to parietal layer with surrounding inflammatory edema. (Fig. 1 A,B).

Fig. 1.

CECT scan showing a radiopaque mass in the right ventral abdominal wall (arrow, A). MRI scan showing a hyper intense nodular lesion in the anterior abdominal wall. (arrow, B).

2.3. Cytopathology

FNAC from the lesion revealed loose clusters of and dispersed spindled to stellate cells, numerous multinucleate giant cells, and histiocytic cells in a haemorrhagic background. A cytological diagnosis of low-grade spindle cell neoplasm suggestive of Fibrous Histiocytoma. She underwent wide local excision of the tumor in which the lesion till depth of parietal peritoneum was removed. (Fig. 2).

Fig. 2.

Cytosmears show scattered spindle cells (A) and multinulceated giant cells (B) in a hemorrhagic background (MGG, 100×).

2.4. Histopathology

Macroscopic examination revealed a poorly circumscribed solitary mass measuring 2x2x1.5 cm, with greyish white cut surface. It was 1 cm away from the skin and was reaching up to the base. (Fig. 3).

Fig. 3.

Gross image showing a poorly circumscribed solitary mass. Cut surface is grey-white glistening.

Microscopic examination revealed tumor with multinodular architecture with intervening fibrous septa and metaplastic bony tissue encasing the tumor. It was composed of mixture of round to oval mononuclear cells and multiple osteoclast like multinucleated giant cells. Focal areas showed hemorrhage resembling aneurysmal bone cyst with presence of hemosiderin laden macrophages. Mitotic figures were eight per 10 high power field. Skin and peripheral margins were free of tumor (Fig. 4 A-D). On immunohistochemical examination the giant cells intense showed CD68 immunoexpression while mononuclear cells showed focal expression. Ki67 was positive in few tumor cell nuclei suggesting a lower proliferation index (Fig. 5 A,B). Pathologically it was diagnosed to be Giant Cell Tumor (GCT) of soft tissue.

Fig. 4.

Bony metaplasia (white arrow) encasing the tumor (A), Multiple variably sized giant cells in fibromuscular stroma (B), Hemorrhagic areas resembling aneurysmal bone cyst (C) and Multiple hemosiderin laden macrophages (D). (H&E, 100×).

Fig. 5.

Photomicrograph showing intense expression of CD68 in giant cells and focally in mononuclear cells (A). Tumor cells showing low expression of Ki67 (B). (DAB, 200×).

2.5. Treatment and follow up

The case was discussed in multidisciplinary joint clinic, and she was offered adjuvant radiotherapy in view of tumor reaching the base and further resection was not feasible. She was treated with 10 MeV electron beam, 45 Gy in 25 fractions with 1.8 Gy per fraction by electron to the skin and post op bed. She tolerated radiotherapy well and post treatment there is no evidence of disease recurrence after one year.

3. Discussion

Giant cell tumor of soft tissue (GCT-ST) is a rare neoplasm with varied clinical, pathological findings. It is predominantly benign. But a local recurrence rate of 10 %–15 % has been reported along with few cases of metastasis. [6]

The tumors in areas of extremities and trunk usually presents as a painless slow growing mass with a mean duration of about 6 months. However, the clinical features can vary depending upon the exact location of the tumor. Luangxay et al. [4] reported a case of GCT-ST in a 59-year-old female presented with a painful mass in breast. Lee et al. [5] reported a case of colonic polypoidal mass at the site of endoscopic Colonoscopic resection done for tubular adenoma with low-grade dysplasia. This shows that this lesion can present at unusual location in varied ways. In the present case the patient had a painful mass in the right abdominal wall.

In lesions presenting as superficial mass, the clinical work is followed by FNAC and radiological examination. In a recent case series, Wakely et al. [14] retrospectively studied the cytopathological features of GCT-ST. They reported that aspiration smears composed of mononuclear polygonal cells, clusters of spindle fibroblast, and large number of osteoclastic type giant cells. They also compared the findings with aspirates from GCT of bone and found that cytological features are mostly comparable. Similar finding was also noted the individual case reports. However, only a few were able to give a diagnosis of GCT-ST on cytopathology. [15], [16] In the present case the aspiration cytology showed variable number of mostly spindled fibroblast, with occasion giant cells and a cytological diagnosis of low grade fibrous histiocytoma was given.

There are limited number of cases reports with radiological description of this tumor. On simple radiographs it does not show any mass-like opacity or bony erosion despite peripheral calcification. [17] In a case report by Calli et al. [3] Ultrasonography of GCT-ST of head and neck show lobulated hypoechoic mass. CT showed soft tissue mass with enhancing margins. The MRI findings shows a mass without a clear tissue plane. It is low in signal intensity similar to muscle on T1-weighted images.

In case series by Wakely et al. majority of the cases were reported as ‘suspicious of sarcoma’ on radiology. Sang Bu An et al. [18] reported one case of GCT-ST showing predominantly cystic mass composed of hypoechoic fluid and debris in the dependent portion within it. Inside the cyst, a hyperechoic nodular lesion was observed. No evidence of bony involvement was found in the literature. In the present case, CECT showed ill-defined enhancing mass lesion deep to muscle planes while MRI showed evidence of hyper intense nodular lesion with surrounding inflammatory edema. The MRI features help in delineation of the tumor and in complete tumor resection.

Histologically, these tumor show a multinodular architecture, with cellular nodules of mononuclear and osteoclast like multinucleated giant cells, these nodules being separated by fibrous septa along with a richly vascular stroma. [2] Mitosis is easily identifiable, can range from 2 to 18 per 10 high power field (median: 5), however, nuclear atypia and pleomorphism is usually absent. [12] Necrosis is rare. About 50 % of cases also show metaplastic bone formation encasing the tumor. Area resembling aneurysmal bone cyst may along with many hemosiderin laden macrophages may be seen. Vascular invasion has also been reported. [9], [11] Immunohistochemistry features are mostly like the GCT bone and has little role in delineating these tumors. Similar to GCT bone, these tumors also express CD68 and SMA, and the osteoclast like giant cells of GCT-ST express TRAP. [19] However immunohistochemistry in not helpful in making the diagnosis. [2]

Histopathological differential diagnosis include other giant cells rich mesenchymal tumors like tenosynovial giant cell tumors and malignant giant cell tumors of soft tissue as well as GCT of Bone. [15] Tenosynovial giant cell tumor, differ in location and contains mixed population xanthoma cells, siderophages, and lymphocytes. Malignant fibrous histiocytoma, giant cell rich comprises of mononuclear and giant cells showing marked atypia, atypical mitosis, and areas of necrosis. [6]

In general, for soft tissue tumors complete surgical resection is the mainstay of treatment. Patients with incomplete resection benefit from adjuvant radiotherapy [20]. Table 1 depicts some studies on GCT-ST.

Table 1.

Studies of GCT-ST.

Reference	Study type	Conclusion
Oliveira et al., 2000 [10]	22 patients Giant cell tumor of soft tissue	2 patients received post-op RT
O Connell 2000 [11]	18 patients	Mostly treated with surgical resection. Benign tumor rarely recurred or metastasized
Calli 2014 [12]	Case report	Postoperative radiotherapy 50 Gy in 25 #
May et al., [14]	Case report	RT not given in Giant cell tumor of breast, aggressive clinical course
Paik et al., 2018 [15]	Case series	Paraspinal GCT treated with Radiosurgery
Chen et al., [16]	SEER database	RT not advocated but no comment on margin

The 5th WHO classification of soft tissue tumors incorporated GCT-ST which has potential for recurrence but rarely metastasize. The clinical behaviour of GCT-ST is better than malignant giant cell tumor of soft parts. [2]

In the present case, tumor was extending to deep margin and further resection was not possible. We treated the patient with electron therapy which is a feasible option for treatment of skin and subcutaneous tissue without significant dose to deeper structures. She tolerated the treatment well.

The risk of recurrence was explained to the patient, and she was asked to come for regular follow-up. She mentioned that she was satisfied with the treatment done and had no similar complaint till last follow up. Clinically no evidence of disease recurrence till last follow up.

4. Conclusion

In conclusion, diagnosis of GCT-ST is difficult on cytopathology and radiology alone. Complete surgical resection with clear resection margins is the mainstay of treatment. Histopathological diagnosis should be done ruling out its close differential diagnoses especially the malignant lesions. Adjuvant radiotherapy should be considered in case of incomplete resection. For superficial tumors electron beam therapy is a clinically feasible option. Long follow-up is necessary for these tumors as local recurrence and risk of metastasis cannot be predicted.

Patient consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

CRediT authorship contribution statement

Drafting the manuscript and Literature research: Shakti Kumar Yadav and Saikat Das

Diagnostic workup: Shakti Kumar Yadav and Deepti Joshi

Treatment planning: Saikat Das and Shyam Lal

Operated on the patient: Shyam Lal

Supervision and critical revision: Deepti Joshi and Neelkamal Kapoor

Ethical approval

Not applicable

Funding

No funding was received.

Research registration

N/A.

Guarantor

Dr Saikar Das and Dr Shakti Kumar Yadav

Declaration of competing interest

Authors declare no conflict of interest.