In some patients there will be a relevant clinical history that indicates the likely nature of a focal testicular
lesion. Examples include intratesticular contusions secondary to trauma, focal orchitis and abscess formation in infection, adrenal rests in patients with congenital adrenal hyperplasia (figure 2), granulomatous masses in patients with sarcoidosis and genitourinary tuberculosis and metastatic tumours in patients with lymphoma or disseminated non-lymphomatous malignancy. Rarely a primary non-germ cell testicular tumour (gonadal stromal tumour) may present with features secondary to tumoural hormone secretion such as gynaecomastia. In many cases however, testicular masses will not have characteristic features or a helpful clinical history; the presence of irregular margins, intra-tumoral calcifications or associated testicular microlithiasis (TML) are all features that indicate an increased probability of malignancy5
. Lack of vascularity on colour or
power Doppler examination increases the probability of a benign aetiology, but blood flow can be difficult to detect within small lesions. In a small series reported in 1992, 86% of tumours smaller than 1.6cm were hypovascular6
systems and absent flow is a reassuring feature in an indeterminate lesion7
. Colour flow is much more reliably demonstrated in smaller lesions with modern ultrasound . In all indeterminate lesions,
the sonographic findings should be interpreted with knowledge of serum testicular tumour markers (beta- human chorionic gonadotropin, alpha-fetoprotein and lactate dehydrogenase). Echopoor, rounded, incidentally discovered impalpable lesions represent the greatest diagnostic challenge, as the majority will have a benign aetiology. However, there are no absolute sonographic features that can differentiate benign from malignant and it is in this group where newer ultrasound techniques are of particular interest.
Contrast-enhanced ultrasound (CEUS) Demonstration of blood flow within hypovascular and small testicular masses may be difficult with conventional Doppler ultrasound. CEUS permits more sensitive demonstration of testicular perfusion though use of microbubble contrast media. Imaging requires specific contrast settings which exploit the harmonic signal generated by microbubble resonance; low acoustic power settings are used to minimise bubble disruption and suppress signal from native tissue. Although B-mode ultrasound is ideally suited to examination of the scrotal contents, the frequency of linear array transducers used for scrotal ultrasound is too high for optimal microbubble resonance; it is often necessary to administer a higher dose of contrast than for abdominal contrast studies and to reduce the transducer frequency to obtain a diagnostic examination. The advantage of CEUS over conventional ultrasound is increased sensitivity in demonstrating the
presence or absence of internal vascularity and particularly to identify those avascular, and therefore likely benign lesions, which could potentially be managed with interval imaging or testicular-sparing surgery. The European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) guidelines8
(figure 3). evaluated 115 impalpable intratesticular lesions and reported the combination of B-mode recommends
CEUS for this indication. A malignant feature on CEUS is a rapid enhancement with a rapid washout contrast enhancement pattern in comparison to the background parenchyma5 Isidori et al5
and CEUS offered a sensitivity of 82% and specificity of 91% in differentiating benign from malignant lesions. Indeterminate enhancement patterns were seen in two metastatic lesions, most likely due to the presence of
-60-
Figure 2: B-mode image showing multifocal predominantly echopoor masses (red
arrows) adjacent to the echogenic mediastinum testis (yellow arrows) seen in both testes on subsequent views; the lesions were present on previous studies and were unchanged. This patient has a known diagnosis of congenital adrenal hyperplasia and in this context the lesions are in keeping with adrenal rests.
Figure 3: B-mode image (right) with superimposed CEUS image (left) showing a subtle echopoor intratesticular lesion (red arrows) which is shown to be hypervascular in the arterial phase (yellow arrows) and demonstrated rapid contrast washout in the subsequent later phases (not shown). This patient had a history of cryptorchidism therefore this lesion must be assumed to represent a small testicular germ cell tumour until proven otherwise, although a sex-cord stromal tumour (Leydig or Sertoli cell) could also have this appearance and are frequently hypervascular on contrast ultrasound. This patient went on to have an orchidectomy with a histological diagnosis of a seminoma.
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