Wolf in a Sheep’s clothing: Advanced Soft Tissue Sarcoma Mimicking A Thigh Abscess

Alok Chhabra*, Amit Goyal, R E Mansel

Address for Correspondence

Alok Chhabra

Department of Surgery, Wales College of Medicine, Cardiff University

Cardiff- CF14 4XN, United Kingdom

Tel: +44 2920744710

Fax: +44 2920761623

Email: chhabraa1@cardiff.ac.uk

Abstract

Soft tissue sarcoma is a rare tumour and the diagnosis is often not suspected before biopsy or excision. We report a 72 year old female with an advanced soft tissue sarcoma who presented initially with symptoms and signs that mimicked a thigh abscess. The diagnosis was missed at the time of surgery and only revealed by the histopathology results of the ‘abscess wall’.
Key Words: abscess, haematoma, malignant fibrous histiocytoma, soft tissue sarcoma

J.Orthopaedics 2007;4(1)e1

Introduction:

Soft tissue sarcoma (STS) is a rare tumour of connective tissue –muscle, tendon, blood vessels, nerves and fat (1% of all malignant tumours). Most sarcomas typically present as a painless mass and are usually discovered incidentally following excision of a lump with no prior suspicion that it could be a sarcoma¹. STS can mimic a haematoma or abscess as haemorrhage and necrosis are not uncommon features in these tumours. We report a 72 year old female with an advanced soft tissue sarcoma who presented initially with symptoms and signs that mimicked a thigh abscess.

Case Report:

A 72 years old female presented to the GP with four weeks history of pain and swelling in left hip following trauma from a car door. She had a past medical history of left hemithyroidectomy for multinodular goitre and MI. On examination she had a tender swelling 5x3 cm in size over the left greater trochanter associated with erythema of overlying skin. Pelvic X-ray showed minor degenerative changes in both hips with no other abnormality.  She was diagnosed to have left trochanteric bursitis and treated with antibiotics. Her symptoms deteriorated after some initial improvement and she was referred to the trauma clinic. Ultrasound scan of the left hip and upper thigh showed large loculated irregular fluid collection consistent with a gluteal abscess. Incision and drainage of the abscess revealed sero-sanguineous fluid with fibrinous flakes. Fluid sent for culture did not grow any organisms. Unfortunately, the swelling recurred and a repeat incision and drainage revealed a large haematoma intraoperatively. Fluid sent for culture did not grow any organisms but tissue sent for histopathology showed features consistent with malignant fibrous histiocytoma. MRI scan revealed large multifocal soft tissue sarcoma in the left hip and upper thigh (Fig: 1). Staging CT scan of chest Abdomen, and pelvis did not show any evidence of distant metastasis. The tumour was treated with radiotherapy and she had a partial response to the treatment.

Discussion :

Soft tissue sarcoma is a rare tumour. It commonly affects the limbs followed by head and neck, trunk and retroperitoneum². It usually present as a painless mass but sometime can mimic a haematoma or abscess. This case highlights that recognition of these features are important as they may be the initial presentation of the underlying malignant disease process.

Soft-tissue sarcomas present unique challenges in detection and treatment. The diagnosis is often not suspected before biopsy or excision. Surgeons should be suspicious and consider doing a biopsy in a patient with: 1) the abscess present in the unusual site like thigh with no specific history, 2) recurrent sterile abscess and 3) when no pus is found during incision and drainage of an abscess. Ultrasound is operator dependent and often is unhelpful in differentiating a soft tissue sarcoma from benign lesions such as abscess or haematoma. MRI scan or CT scan should be requested when the diagnosis is in doubt.

Treatment of soft tissue sarcoma is mainly surgical which includes wide local excision of the tumour. Radiotherapy is indicated for large and high grade tumours and chemotherapy for specific tumours like Ewing’s sarcoma and rhabdomyosarcomas. The 5- year survival rate is 50-60% as a group³⁴⁵.

In conclusion, tumour size at presentation adversely affects the patient prognosis. Therefore delay in diagnosis should be avoided and the patient should be managed by Multi Disciplinary Team for the best outcome.

Reference :

1. Fletcher CD, et al., Clinicopathologic re-evaluation of 100 malignant fibrous histiocytomas: prognostic relevance of subclassification. J Clin Oncol., 2001. 19(12): 3045-50.

2. Enjoji M, et al., Malignant fibrous histiocytoma. A clinicopathologic study of 130 cases. Acta Pathol Jpn., 1980. 30(5):727-41.

3. Ekfors TO and R. V., An analysis of 38 malignant fibrous histiocytomas in the extremities. Acta Pathol Microbiol Scand, 1978. 86(1):25-35.

4. Rooser B, et al., Malignant fibrous histiocytoma of soft tissue. A population-based epidemiologic and prognostic study of 137 patients. Cancer, 1991. 67(2): 499-505.

5. Rydholm A, et al., Epidemiology of soft-tissue sarcoma in the locomotor system. A retrospective population-based study of the inter-relationships between clinical and morphologic variables. Acta Pathol Microbiol Immunol Scand, 1984. 92(5):363-74.

This is a peer reviewed paper 

Please cite as : Alok Chhabra:Wolf in a Sheep’s clothing: Advanced Soft Tissue Sarcoma Mimicking A Thigh Abscess

J.Orthopaedics 2007;4(1)e1

URL: http://www.jortho.org/2007/4/1/e1

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