CASE 9789 Published on 22.12.2011

Epidermoid cyst of the testis: value of MR imaging in preoperative characterisation

Section

Uroradiology & genital male imaging

Case Type

Clinical Cases

Authors

Aikaterini Ntoulia, Athina C. Tsili, Konstantinos Tsampoulas

University Hospital of Ioannina,
Clinical Radiology, Dept. Of Radiology;
Pl. Patgis 2 45332 Ioannina, Greece;
Email:a_tsili@yahoo.gr

Patient

25 years, male

Categories

Area of Interest Genital / Reproductive system male ; Imaging Technique MR

Procedure Imaging sequences, Image compression ; Special Focus Tissue characterisation ;

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Clinical History

A 25-year old man was referred for a palpable scrotal mass. Clinical examination revealed a smooth, firm, painless right intratesticular mass. Laboratory analysis, including serum markers for testicular germ cell tumours, was unremarkable.

Imaging Findings

MR imaging examination of the scrotum was performed on a 1.5 Tesla scanner, using a pelvic phased-array coil. The protocol included axial spin-echo T1-weighted, fat-suppressed T1-weighted and fast spin-echo T2-weighted sequences in orthogonal planes. Diffusion-weighted imaging was performed axially, using a single shot, multi-slice spin-echo planar diffusion pulse sequence and b-values of 0 and 900 sec/mm2. Dynamic contrast-enhanced MR imaging in coronal plane and transverse spin-echo contrast-enhanced T1-weighted images were also obtained.
A sharply-demarked right intratesticular lesion was detected, mainly isointense on T1-weighted images, compared to normal testis (Fig. 1), with concentric alternating rings of high and low signal intensity on T2-weighted images (Fig. 2), the latter suggestive for the diagnosis of epidermoid cyst. Diffusion-weighted imaging revealed restricted diffusion (Fig. 3), due to the presence of dense keratinised material. No enhancement was detected after gadolinium administration, confirming the diagnosis of benignity. Radical orchiectomy was performed and an epidermoid cyst was found on pathology.

Discussion

Background
Epidermoid cyst is a rare, intratesticular benign lesion that accounts for approximately 1% of all testicular masses [1-10]. Histologically, it is composed of concentric layers of laminated keratinous material, responsible for its characteristic imaging appearance. The lesion is encapsulated, surrounded by a well-defined fibrous wall lined by squamous epithelium [1-4]. An accurate preoperative diagnosis of the benign nature of epidermoid cyst, based on imaging features, may justify avoidance of radical orchiectomy in these patients.
Sonography, although the primary imaging technique for the evaluation of scrotal masses, does not always allow their confident preoperative characterization [11]. MR imaging of the scrotum has been used as an alternative imaging modality for the evaluation of scrotal masses [1, 12-15]. The technique due to its wide field of view, multiplanar capabilities, high contrast and spatial resolution has proved satisfactory in the localization of a scrotal mass, and the characterization of the histologic nature of various scrotal masses. However, the technique is mainly recommended when sonographic findings are inconclusive or inconsistent with clinical findings [1, 14, 15].
Imaging perspective
Sonographic features include a sharply demarcated, markedly heterogeneous intratesticular solid mass. The presence of concentric alternating rings of hypo- and hyper-echogenicity, providing a characteristic “target” or “onion-skin” appearance, is considered a finding supportive for its diagnosis. A hyperechoic rim, sometimes calcified, can be seen at the periphery of the lesion. Colour Doppler reveals no lesion vascularity [1-4].
Consistent with the abovementioned sonographical findings are the MR features of epidermoid cysts, further supporting their accurate preoperative characterization. Typically, the lesion is surrounded by a hypointense rim on both T1- and T2-weighted images, corresponding to the outer fibrous capsule. Alternating zones of high and low signal intensity on T2-weighted images, corresponding to both high water and lipid content, and dense keratin debris and calcifications, on pathology is considered as highly suggestive for the diagnosis. These calcium depositions may be responsible for the paradox hyperintensity seen on T1-weighted images centrally within the lesion, as in this case [16]. Absence of contrast enhancement confirms lesion benignity. Advanced MR applications, such as diffusion-weighted imaging does not further facilitate its diagnosis, since water mobility restriction in epidermoid cyst due to high viscosity material, can also be detected in intratesticular malignancies.
In concluding, imaging findings may strongly suggest the benign nature of epidermoid cyst preoperatively, allowing for lesion enucleation or partial orchiectomy in these patients.

Differential Diagnosis List

Epidermoid cyst

Testicular carcinoma

Abscess

Isolated granulomatous orchitis

Chronic orchitis

Infarction with internal haemorrhage

Final Diagnosis

Epidermoid cyst

References

[1] Woodward PJ, Sohaey R, O\'Donoghue MJ, Green DE (2002) From the archives of the AFIP: tumors and tumorlike lesions of the testis: radiologic-pathologic correlation. Radiographics 22:189-216 (PMID: 11796908)

[2] Loya AG, Said JW, Grant EG (2004) Epidermoid cyst of the testis: radiologic-pathologic correlation. Radiographics 24 Suppl 1:S243-6 (PMID: 15486244)

[3] Malek RS, Rosen JS, Farrow GM (1986) Epidermoid cyst of the testis: a critical analysis. Br J Urol 58:55-9 (PMID: 3947857)

[4] Cho JH, Chang JC, Park BH, Lee JG, Son CH (2002) Sonographic and MR imaging findings of testicular epidermoid cysts. AJR Am J Roentgenol 178:743-8 (PMID: 11856711)

[5] Moghe PK, Brady AP (1999) Ultrasound of testicular epidermoid cysts. Br J Radiol 72:942-5 (PMID: 10673943)

[6] Langer JE, Ramchandani P, Siegelman ES, Banner MP (1999) Epidermoid cysts of the testicle: sonographic and MR imaging features. AJR Am J Roentgenol 173:1295-9 (PMID: 10541108)

[7] Cittadini G, Gauglio C, Pretolesi F, Santacroce E, Derchi LE (2004) Bilateral epidermoid cysts of the testis: sonographic and MRI findings. J Clin Ultrasound 32:370-2 (PMID: 15293307)

[8] Shah KH, Maxted WC, Chun B (1981) Epidermoid cysts of the testis: a report of three cases and an analysis of 141 cases from the world literature. Cancer 47:577-82 (PMID: 7226006)

[9] Kim W, Rosen MA, Langer JE, Banner MP, Siegelman ES, Ramchandani P (2007) US MR imaging correlation in pathologic conditions of the scrotum. Radiographics 27:1239-53 (PMID: 17848688)

[10] Loberant N, Bhatt S, Messing E, Dogra VS (2011) Bilateral testicular epidermoid cysts. J Clin Imaging Sci 1:4 (PMID: 21915385)

[11] Dogra VS, Gottlieb RH, Oka M, Rubens DJ (2003) Sonography of the scrotum. Radiology 227:18-36 (PMID: 12616012)

[12] Cassidy FH, Ishioka KM, McMahon CJ, Chu P, Sakamoto K, et al (2010) MR imaging of scrotal tumors and pseudotumors. Radiographics 30:665-683. (PMID: 20462987)

[13] Tsili AC, Argyropoulou MI, Giannakis D, Sofikitis N, Tsampoulas K (2010) Magnetic resonance imaging in the characterization and local staging of testicular neoplasms. AJR 194:682-689. (PMID: 20173145)

[14] Muglia V, Tucci S, Elias J, Trad CS, Bilbey J, et al (2002) Magnetic resonance imaging of scrotal diseases: when it makes the difference. Urology 59: 419-423. (PMID: 11880084)

[15] Serra AD, Hricak H, Coakley FV, Kim B, Dudley A, et al (1998) Inconclusive clinical and ultrasound evaluation of the scrotum: impact on magnetic resonance imaging on patient management and cost. Urology 51:1018-1021. (PMID: 9609643)

[16] Henkelman RM, Watts JF, Kucharczyk W (1991) High signal intensity in MR images of calcified brain tissue. Radiology 179(1):199-206. (PMID: 1848714)

Case information

URL:	https://www.eurorad.org/case/9789
DOI:	10.1594/EURORAD/CASE.9789
ISSN:	1563-4086

Figure 1

Epidermoid cyst

Axial T1-weighted image. An intratesticular mass lesion is demonstrated in the upper pole of the right testis (arrow), with smooth, well defined margins. A hyperintense area is seen centrally (arrowhead).

Transverse fat-suppressed T1-weighted image shows hyperintensity of the lesion center (arrowhead), corresponding to dense keratinised material and calcifications, on histology.

Figure 2

Epidermoid cyst

Transverse T2-weighted image demonstrates the typical “onion-skin” appearance of the lesion (arrow), corresponding to the laminated layers of keratinised material, on pathology. Imaging findings were suggestive for the diagnosis of epidermoid cyst.

Sagittal T2-weighted image. The lesion (arrow) is surrounded by a rim of low signal intensity, detected on both T1 and T2-weighted images, corresponding to fibrous wall on pathology.

Coronal T2-weighted image. A central focus with low signal intensity can be discerned within the lesion (arrow), corresponding to area of hyperintensity on T1-weighted images.

Figure 3

Epidermoid cyst

DW image (b=900 s/mm2) in axial plane demonstrates lesion hyperintensity (arrow), suggestive for significant water molecules diffusivity restriction due to the presence of dense internal material.

Corresponding ADC map (Figure 3a). The ADC values of the lesion (arrow) are 0.68 s/mm2 (arrow), compared to those of the contralateral testis (1.08 s/mm2).

Figure 4

Epidermoid cyst

Dynamic contrast-enhanced image (early phase) in sagittal plane demonstrates no lesion (arrow) enhancement.

Axial T1-weighted image with fat suppression after intravenous administration of gadolinium shows absence of contrast medium uptake (arrow), highly suggestive of lesion benignity.