Detection of recurrent cutaneous angiosarcoma of lower extremity with (18)f-fluorodeoxyglucose positron emission tomography-computed tomography: report of three cases.

Cutaneous angiosarcomas (CAS) are uncommon, aggressive tumours. Very rarely, they arise from the lower extremity. Such tumours are usually associated with chronic lymphedema, a phenomenon known as Stewart-Treves Syndrome. Treatment is usually radical surgery with adjuvant therapy (radiotherapy/chemotherapy). Recurrence rate after primary treatment is high. Because of post therapy changes, conventional imaging has limited specificity for diagnosing recurrence. (18)F-Fluorodeoxyglucose ((18)F-FDG) positron emission tomography-computed tomography (PET-CT) might be useful in such patients. It can demonstrate local recurrence along with distant metastasis, if any and can have significant impact on patient management. We here present three cases of recurrent CAS of lower extremity diagnosed with (18)F-FDG PET-CT.

What was known?

1. Cutaneous angiosarcomas of lower extremity are rare aggressive neoplasm.

2. Clinical examination or conventional imaging has limited specificity for diagnosing local recurrence after treatment of such tumours.

Introduction

Cutaneous angiosarcomas (CAS) are rare tumours mostly seen in scalp of elderly patients.[1] CAS of lower extremity is rarer and usually seen in association with chronic lymphedema, the entity being known as Stewart-Treves Syndrome (STS).[2] These tumours are aggressive and have high rates of recurrence and metastasis.[3] As the primary tumours are treated with surgery, sometimes with adjuvant radiotherapy, it is often difficult to differentiate recurrent tumours from post therapy changes.[3] Metabolic imaging with 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) might be useful in such patients. We present here three cases of recurrent CAS of lower extremity detected with 18F-FDG PET-CT and briefly review the role it can play in management of such tumours.

Case Reports

Case 1

A 39 year old female with history of chronic lymphedema of left leg, developed a non healing ulcer. Biopsy from the ulcer revealed angiosarcoma (STS). She underwent 18F-FDG PET-CT for staging. It revealed multiple 18F-FDG avid (SUVmax-4.5) cutaneous nodules on anterior aspect of left leg [Figures 1a and 2a-c] but no distant metastasis. She underwent radical surgery followed by four cycles of chemotherapy. 18F-FDG PET-CT was repeated to assess response one month after completion of chemotherapy. Complete resolution of cutaneous lesions was seen, suggesting complete response [Figures 1b and 2d-f]. The patient then lost to follow up and presented 2 years later with multiple cutaneous nodules in left leg. 18F-FDG PET-CT study was repeated for any distant metastasis. Multiple large 18F-FDG avid (SUVmax-7.3) necrotic cutaneous nodules were seen in left leg suggesting extensive recurrent disease [Figures 1c and 2g-i] but no distant metastasis was seen. The patient was advised for an amputation, which she refused. She is on palliative radio-chemotherapy.

Figure 1

A 39 year old female with Stewart-Treves Syndrome (Case 1). Maximum intensity projection (MIP) PET images at baseline (a) reveal multiple 18F-FDG avid lesions in the left leg anteriorly. Repeat study done after surgery and chemotherapy (b) shows no such focus, except for 18F-FDG uptake in muscle (arrowhead). After 2 years a third PET-CT (c) was done, which show multiple 18F-FDG avid lesions in leg, extending upto left thigh suggesting recurrent disease

Figure 2

PET-CT images of the above patient (Case 1). Upper row show baseline CT (a) PET (b) and PET-CT (c) images. The images show cutaneous and subcutaneous thickening (arrow) with increased FDG uptake. PET-CT was done after surgery and chemotherapy (d-f) shows postoperative change with no significant 18F-FDG uptake suggesting complete response to therapy. Repeat PET-CT images (g-i) done after 2 years shows large necrotic FDG avid lesions in the left leg (arrow) suggesting recurrent disease. This was confirmed on biopsy

Case 2

A 58 year old woman with history of chronic lymphedema of left leg developed a 2.5 × 3 cm reddish patch over the left leg. Biopsy revealed angiosarcoma (STS). She underwent wide local excision of the tumour followed by skin grafting. Three months after the surgery, she complained of discomfort at the surgery site along with bone pains. Magnetic resonance imaging (MRI) of the lower limbs was suggestive of post-operative changes. Restaging 18F-FDG PET-CT was done to look for distant metastasis. No distant metastasis was seen [Figure 3a]. However, it revealed cutaneous thickening in left leg antero-laterally with increased 18F-FDG uptake (SUVmax-2.7) [Figure 3b-e], suspicious for local recurrence. The diagnosis was confirmed with biopsy. She underwent re-operation followed by adjuvant chemotherapy and is well at 6 month follow up.

Figure 3

A 58 year old female with Stewart-Treves Syndrome (Case 2). She underwent PET-CT for suspected recurrence of cutaneous angiosarcoma of left lower limb. Whole body maximum intensity projection (MIP) PET image (a) does not show any distant metastasis. MIP PET images of lower limbs (b) reveal focally increased 18F-FDG uptake in the antero-lateral part of left leg (arrow). Transaxial CT (c) PET (d) and PET-CT (e) images show cutaneous thickening with increased 18F-FDG uptake in antero-lateral part of left lower leg (arrow), suspicious for local recurrence. This was confirmed with biopsy

Case 3

A 72 year old male developed 5 × 3.2 cm purplish-red cutaneous papule in the posterior aspect of left lower limb. There was no lymphedema. The tumour was resected and histopathology revealed angiosarcoma. Staging investigations at the time of surgery were negative. The patient presented with stiffness and discomfort at the operated site one year later. 18F-FDG PET-CT was done. It revealed cutaneous thickening with increased 18F-FDG uptake (SUVmax-3.3) in the left popliteal region [Figure 4b-d] but no distant metastasis [Figure 4a]. 18F-FDG PET-CT was suggestive of local recurrence only. The patient underwent surgery for removal of the tumour and is doing fine at 18 months follow up.

Figure 4

A 72 year old male with cutaneous angiosarcoma of left lower limb (Case 3). The lesion was surgically resected. 18F-FDG PET-CT was done 1 year later for suspected local recurrence. Whole body maximum intensity projection (MIP) PET image (a) does not show any distant metastasis. Transaxial CT (b) PET (c) and PET-CT (d) images show 18F-FDG avid cutaneous thickening in the popliteal region of left leg extending to involve the underlying muscles (arrow). Findings were suggestive of local recurrence and confirmed with biopsy

Discussion

CAS are high-grade and highly aggressive endothelial-cell tumours of vascular or lymphatic origin, with a high incidence of metastasis at presentation.[3-5] They constitute 5.4% of cutaneous soft tissue sarcomas.[6] It typically involves the head and neck, particularly the scalp. Angiosarcomas of the extremities are rare. Chronic lymphedema and previous radiotherapy are two well documented risk factor for development of CAS.[27] Chronic lymphedema of any origin is associated with the development of angiosarcoma; a phenomenon known as STS.[2] The primary treatment is usually radical surgery. Despite radical surgery, recurrence rates are high. So, multimodality treatment (radiotherapy/chemotherapy) is usually employed and has been shown to be beneficial.[3] Even with multimodality treatment there is high risk of recurrence. Additional surgery in locally-recurrent disease to achieve a pathological complete resection may improve survival in such patients.[8] This highlights the need to diagnose recurrent disease at its earliest. Computed tomography (CT) and magnetic resonance imaging (MRI) are used for primary staging of these tumours, but their role is limited in recurrent tumours because of low specificity due to post surgical and post radiotherapy changes.

18F-FDG PET-CT is being utilised for wide array of tumours, including cutaneous neoplasms.[9] It has also been shown to be useful in primary angiosarcoma of various sites, even CAS.[1011] Vasanawala, et al. previously reported the utility of 18F-FDG PET-CT for diagnosis and restaging in a case of CAS of scalp.[12] Similarly, Jensen, et al. have shown the utility of 18F-FDG PET-CT in two cases of Stewart-Treves Syndrome.[10] Dawlatly, et al. showed efficacy of 18F-FDG PET-CT in two cases of STS of lower extremity and found PET-CT to be helpful in demonstrating the extent of subcutaneous spread and planning surgical management.[13] However, to our knowledge utility of 18F-FDG PET-CT in recurrent CAS has not been reported till date. We found 18F-FDG PET-CT to be very useful. This is true for Stewart-Treves Syndrome (case 1 and 2) as well as spontaneous tumours (case 3). In all three patients 18F-FDG PET-CT was able to demonstrate recurrent disease. It could be superior to MRI for detecting local recurrence (case 2). The 18F-FDG avidity of recurrent tumour varied with SUVmax ranging from 2.7 to 7.3 and is probably related to biological aggressiveness. In case 1 the recurrent tumour was more aggressive as demonstrated by increase in SUVmax from baseline (4.5 to 7.3). Apart from demonstrating local recurrence another major utility of 18F-FDG PET-CT was to rule out distant metastasis at staging (case 1) or at restaging (case 2 and 3). This is especially important in these tumours given the high incidence metastasis.[5]

In conclusion, 18F-FDG PET-CT appears to be useful for diagnosing recurrent CAS. It influences patient management by demonstrating local recurrence and ruling in/out distant metastasis. These findings if confirmed in larger patient population might lead to integration of 18F-FDG PET-CT in management protocols of CAS.

What is new?

1. 18F-FDG PET-CT can be used for detecting local recurrence in cutaneous angiosarcoma of lower extremities.

2. It can also detect or rule out distant metastasis in this setting.