Using contrast-enhanced ultrasound to guide a successful biopsy of a splenic sarcomatoid carcinoma

Introduction

Splenic lesions are uncommon and frequently cause diagnostic dilemmas, a consequence of non-specific findings on ultrasound (US) and cross-sectional imaging. When malignancy is suspected, a histological diagnosis is required. Histological diagnosis has traditionally been obtained via splenectomy; however, imaging-guided percutaneous core needle biopsy (PCNB) has become more established, despite previous reservations of safety. PCNB is now acknowledged to be less invasive than splenectomy with reduced patient morbidity. However, PCNB is not without risk of haemorrhage and may produce an insufficient sample, particularly in necrotic lesions. ¹ Steps to reduce complications and to increase diagnostic yield should be sought. We present a case where contrast-enhanced US (CEUS) was able to discern viable tumour from necrotic regions, allowing increased accuracy in lesion targeting and reducing the number of passes required for biopsy whilst maximising histological yield.

Case report

A 75-year-old man presented to the emergency department with left-sided abdominal pain and a vague history of trivial trauma. On clinical examination, there was left upper quadrant tenderness. Serological and biochemical markers were unremarkable. Contrast-enhanced computed tomography (CT) demonstrated a large, peripherally enhancing, predominantly cystic mass surrounding the spleen. The mass showed close relationship to the stomach and to a thickened left hemi-diaphragm. There was an associated left-sided pleural effusion (Figure 1).

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Figure 1.

CT demonstrates a peripherally enhancing, predominantly cystic lesion (arrow) surrounding the spleen (star).

Greyscale US revealed a left upper quadrant mass, involving the spleen. The mass was centrally heterogeneous with peripheral hypoechoic presumed fluid components. Colour Doppler ultrasound (CDUS) showed no intralesional vasculature, but normal splenic hila vessels were demonstrated (Figure 2). CEUS was performed on a Logiq E9 (GE Healthcare) unit with a C1-6 transducer. CEUS demonstrated compressed splenic parenchyma with large areas of non-enhancing tissue occupying the majority of the central mass in keeping with central necrosis and disorganised peripheral nodular enhancement. The enhancing regions of the lesion demonstrated wash-out in the delayed phase, suggestive for malignancy (Figure 3). With the suspicion of a malignancy, possibly an angiosarcoma of the spleen, the patient was referred to a regional oncology centre. There was a requirement for confirmation on biopsy and, in the presence of substantial areas of necrosis, a suggested minimum of 12 samples to be taken. To minimise the risks associated with splenic PCNB, CEUS-guided biopsy was undertaken to target the lesions solid components.

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Figure 2.

Greyscale ultrasound demonstrates a heterogeneous mass with apparent peripheral fluid components (arrow). Doppler demonstrates splenic hila vessels (star), however no intralesional vascularity.

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Figure 3.

CEUS demonstrating compressed, enhancing splenic parenchyma with disorganised peripheral nodular enhancement (star) and large areas of non-enhancing necrosis (arrow).

US-guided core-needle biopsy was undertaken in accordance to normal local protocols. 2.4 ml SonoVue was injected via a peripherally sited cannula located in the left antecubital fossa. CEUS imaging was conducted throughout the arterial and venous phases with an initial video loop of 60 seconds, followed by single still images which were taken into the late phase.

Using a suitable location, the probe was positioned such as to demonstrate a clear path to a region of enhancing splenic parenchyma while avoiding all areas of necrosis and demonstrable vessels to minimise the risk of haemorrhage. Then, 10 ml 1% lignocaine was infiltrated into the subcutaneous tissues and a repeat 2.4 ml intravenous injection of SonoVue was undertaken. An 18 g coaxial biopsy needle was then introduced through the coaxial system (TenmoTM, Merit Medical) and gently advanced under real-time CEUS imaging through the arterial phase, in order to avoid intercostal arteries. Through the venous phase, real-time imaging continued and allowed the coaxial 18 g needle to be guided into the solid vascular components of the splenic lesion while avoiding the non-enhancing necrotic areas (Figure 4). Guidance of the biopsy needle was enhanced by the use of dual screen applications demonstrating both CEUS and greyscale images simultaneously. Five cores were obtained. Prophylactic haemostatic gelatine sponge was administered through the coaxial needle after the biopsy needle was withdrawn under US guidance. Continued imaging under CEUS was performed to ensure there was no active extravasation of contrast to suggest arterial bleeding either from an intercostal or intralesional site. Standard post procedure recovery and observation was performed.

Five PCNB samples were obtained, sufficient to establish the diagnosis of a sarcomatoid carcinoma of unclear origin, likely splenic. The patient was referred for palliative chemotherapy.

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Figure 4.

CEUS providing real-time guidance of the biopsy needle targeting peripheral solid elements (arrow), avoiding necrotic areas (star).

Discussion

To the authors’ knowledge, this case is the first to describe CEUS guided PCNB of the spleen. The addition of CEUS guidance allowed the operator to target solid areas of enhancing, viable lesional tissue. This reduced the number of passes required and subsequently the risk of haemorrhage. The use of CEUS in this case ensured patient safety while maximising diagnostic yield for histological assessment.

Ultrasound contrast agents (UCA) consist of soluble microbubbles of inert gas encapsulated in a phospholipid shell. UCA have no known cardiac, hepatic- or nephrotoxic effects. The gaseous components are exhaled by respiration and the lipid shell is metabolised by the liver. Adverse reactions of CEUS is low in both adults and children which is comparable to common place antibiotics and less than those of iodinated contrast agent currently used in CT.^2,3 The UCA is a pure blood pool agent. ⁴ CEUS is radiation free, real time and readily available as a bedside test, ideal for interventional use. ^4–7 CEUS PCNB allows real-time imaging for the operator with direct needle visualisation, furthermore post-biopsy complications such as bleeding or pseudoaneurysm formation can be immediately assessed and active management undertaken.^4–7

Percutaneous biopsy has transformed patient management allowing histological analysis and personalisation of therapy. In the diagnosis of splenic lesions, PCNB has allowed for diagnostic certainty without the need for splenectomy and potential of subsequent immunocompromisation. However, splenic biopsy is still perceived to have a high-risk of haemorrhage, with complication rates being documented as high as 5.8%. ¹ The perceived high risk of splenic biopsy along with an estimated sensitivity rate of 87% can discourage operators from performing a PCNB of the spleen. ¹

Image-guided PCNB is usually performed under CT or US guidance. CT guidance of PCNB is a static, non-portable modality which uses nephrotoxic contrast agents and ionising radiation – limiting its use to patients with suitable renal function and reasonable mobility. CT is further disadvantaged as it cannot safely provide real-time image guidance, with contrast washout during the procedure rendering anatomical landmarks diminished. Conventional US guidance has the ability to perform PCNB in real time and in a bedside setting, but lacks the ability to detect microvasculature alterations. CEUS has the ability to demonstrate both macrovascular and microvascular structures in real time, and often readily characterises lesions as benign or malignant negating the need for biopsy.^5–8 CEUS increases lesion conspicuity for a prolonged period, improving real-time lesional targeting and potentially decreasing procedural time. Biopsy can be undertaken in either arterial or venous phases and multiple reinjections of the US contrast agent can be performed without patient compromise,^2–3 which is not possible with a CT guided procedure. The purely intravascular nature of the agent allows differentiation between vascular tumour tissue and non-enhancing necrotic tissue, 5 helping to increase histological yield.^5,8

CEUS has been proven to increase success rates in biopsies of focal liver lesions, providing more accurate information about the biopsy site, reducing the number of puncture attempts and improving the diagnostic accuracy of the initial liver biopsy. ^5–8 Physician apprehension surrounding the safety of a splenic biopsy is postulated to be due to early biopsy attempts using 14 gauge needles.^1,9 More recent studies have suggested that PCNB represents a safe alternative with risk comparable to liver biopsy.⁹ There remains the possibility of catastrophic bleeding and measures should be undertaken to manage this complication in highly vascular lesions, but whilst taking care not to obtain an inadequate sample.^1,5,8 A fine needle aspiration for splenic lesions may be able to reduce the potential risks and allow for the immediate detection of complications and expedite treatment.10

In conclusion, this case demonstrates the novel utility of CEUS in guiding PCNB to maximise histological yield in an indeterminate but likely malignant splenic tumour. CEUS-guided PCNB was able to discern necrotic tissue from vascularised parenchyma, ensuring histological sampling from diagnostic sample sites and highlighting the importance of CEUS in demonstrating the vascular phases of imaging in real time. The authors suggest that the use of CEUS-guided PCNB of the spleen could help to increase operator confidence in the procedure and improve diagnostic yield.