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Testicular mass in a resting cell

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Q1: What does the ultrasound scan show?

The ultrasound scan shows bilateral hypoechoic intratesticular masses. The margins are well defined and the lesions are in close proximity to the rete testis (mediastinum testis).

Q2: Given the patient’s history, what is the diagnosis?

The diagnosis is bilateral adrenal rest tumours or testicular tumours of adrenogenital syndrome.

Q3: Describe the pathophysiology of these lesions?

An adrenal cortical cell rest, an interstitial cell, and a pleuripotent cell have all been suggested as the origin of testicular masses in congenital adrenogenital syndrome.1,2 Embryologically the development of the adrenal gland and the genital ridge occurs in close proximity. Adrenal cell rests are therefore known to occur in the spermatic cord, testis, broad ligament, and the ovary.3

The normal pathway of synthesis of the steroids hormones is shown in fig 1. The commonest defect in adrenogenital syndrome or congenital adrenal hyperplasia is complete or partial deficiency of 21-hydroxylase followed by a deficiency of 11-β-hydroxylase. The enzyme 21-hydroxylase is crucial to the synthesis of both cortisol and aldosterone. A lack of this enzyme leads to excess synthesis of adrenal androgens and also stimulation of secretion of adrenocorticotrophic hormone (ACTH). This ACTH in turn acts on the adrenal tissue, including the ectopic adrenal cell rests leading to hyperplasia and formation of testicular masses in male patients. Hyperplasia of testicular adrenal rest cells is also known to occur in patients with Nelson’s syndrome who have undergone adrenalectomy of the native glands.4

Figure 1

 Pathway of steroid hormone synthesis.

Histologically the smaller lesions are located at the hilus in 86% as shown by Rutgers et al.1 The larger lesions are more commonly situated in the testicular parenchyma. They tend to be well demarcated, unencapsulated brown green masses separated into lobules by bands of fibrous tissue.

Microscopically the most important differentiating feature from a Leydig cell tumour is the absence of renke crystals.1,2,5 Clinically adrenogenital syndrome exists in three forms—that is, prenatal virilisation with or without salt wasting, a late onset form, and an asymptomatic form. The testicular masses occur more commonly in the salt loosing form.1 They need not always be clinically palpable. These patients with congenital adrenal hyperplasia are prone to infertility secondary to impaired spermatogenesis and Leydig cell failure, both in the testicular masses group as well as in patients with no testicular masses.5–8 Treatment with hormone replacement (dexamethasone) is shown to reduce the size of these lesions as well as a reduction in the hardness of the testis. Compliance with treatment is shown to prevent their occurrence.2,9 A lack of decrease in size with compliance to treatment is also seen and can be secondary to extensive fibrosis or calcification in the lesions at diagnosis.2 However a study by Stikkelbroeck et al showed no significant correlation of the tumour size to the hormone replacement regimens or under treatment of these patients.5

Q4: What is the role of imaging in the management of these lesions?

The presence of testicular tumours in congenital adrenal hyperplasia is well known but their diagnosis and management have always been a dilemma because of the inability to accurately diagnose the benign nature of the tumours. With advances in imaging techniques it is now possible to more accurately categorise the lesions, though the differential of a Leydig cell tumour will always need to be considered in the asymptomatic group with no hormonal dysfunction. Imaging plays a crucial part both in the diagnosis and follow up of these lesions. Ultrasound and magnetic resonance imaging (MRI) have equivalent sensitivity in detecting and assessing the size of the lesion.10

These tumours tend to be bilateral, located closer to the hilum and can be intratesticular or in the spermatic cord. On ultrasound they are usually hypoechoic but can be hyperechoic.10,11 Colour Doppler sonography can reveal a hypervascular or hypovascular nature and if hypervascular they have a characteristic spokewheel pattern.10 On T1 weighted MRI most are isointense (71%) but some can be hyperintense relative to the testicular tissue. After contrast they show enhancement. On T2 weighted MRI they are hypointense in relation to the testicular tissue (fig 2).10,12

Figure 2

 T2 weighted MRI scan of both testis showing isointense masses.

Ultrasound and MRI are used in following up these lesions while the patient receives hormonal replacement as they are known to reduce in size with treatment.9 However they can be unresponsive to steroid treatment and may also gain autonomy. Imaging can prove useful in assessing unresponsiveness provided the patient is compliant to medication. In such circumstances resection of the tumour with testis sparing surgery is advocated in order to retain fertility.12 Postoperative MRI and ultrasound can be used for evidence of recurrent disease.

Learning points

  • All testicular masses are not cancers.

  • Patients with adrenogenital syndrome can develop testicular tumours in adrenal rest cells.

  • Compliance to hormone replacement therapy is beneficial.

  • Hormone replacement or testis sparing surgery are available options.

  • Definitive diagnosis is difficult.

Final diagnosis

Bilateral adrenal rest tumours or testicular tumours of adrenogenital syndrome.

References

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