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Pelvis » Scrotum And Testicles
Leydig Cell Tumor of the Testicle
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Presentation This is a 35 year-old male patient who presented for presurgical assessment of left Inguinal hernia. Scrotal and inguinal ultrasound was requested.
Caption: Figure 1. Ultrasound of the left testicle, longitudinal (a.) and axial (b.)
Description: These images show a hypoechoic nodule (solid) in the left testicle, slightly heterogeneous that measures 7.8 mm x 5.7 mm x 5.2 mm in longitudinal, anteroposterior and transverse diameters.
Caption: Figure 2. Ultrasound of the left testicle, longitudinal scan with Power Angio.
Description: The nodule has predominantly peripheral and low internal vascular flow.
Differential Diagnosis
• Testicular tumor
• Lymphoma
• Metastasis
• Sarcoidosis
• Ectopic adrenal tissue

Final Diagnosis Testicular tumor: Leydig Cell Tumor
Ultrasound can detect masses of the scrotum with a sensitivity of 100%. Its specificity ranges from 98% to 100% in distinguishing intratesticular from extratesticular masses. This is important because most of the extratesticular masses are benign whereas the majority of the intratesticular ones are malignant.

Testicular cancer accounts for 1% of neoplasms in men but is the most common malignant tumor in young men between 15 and 34 years old. The most frequent clinical manifestation is a painless scrotal mass (65% - 95%). Other symptoms include scrotal heaviness or lower abdominal pain (10%). A minority of the patients present with endocrine disorders, such as gynecomastia, impotence, loss of libido or precocious virilization. Interestingly, some tumors can disappear (“burned out tumors”) due to necrosis and scarring so that these patients have normal or smaller testicles but present at the stage of metastases.

Primary testicular neoplasms have been classified into two main categories: germ cells tumors (GCT) and non germ cell tumors (NGCT). Germ cell tumors represent 90- 95% of the total and they are the most common malignant neoplasm in young adults. The remainder 5% - 10% are non-germ cells tumors (NGCT) which are usually benign. Metastasis to the testis as well as Lymphoma are rare. 
The most common GCTs are seminomas (S) and the next most common is mixed germ cell tumor (a type of non seminoma tumor). On US, seminomas are generally well- defined, hypoechoic and homogeneous lesions that can be multifocal. The mixed-germ cell tumors tend to be complex cystic masses (representing areas of necrosis, hemorrhage) and can present calcifications.

The NGCT include Leydig cells tumors (LCT) derived from the gonadal stroma and Sertoli cell tumors (SCT) derived from the sex cords. At ultrasonographic examination LCT are usually small, homogeneous and hypoechoic masses.  Foci of hemorrhage and necrosis (cystic spaces and hyperecogenic foci) are present in 25% of the tumors, especially if they are large. With Color Doppler they may show mainly peripheral flow. However, Doppler US depends more on the size of the mass than on the histologic nature. In general, lesions greater than 15 mm are hypervascular whereas smaller lesions present as hypovascular masses.

Macroscopically, LCTs are circumscribed golden brown nodules, usually less than 5 cm, with homogeneous cut surface. Histologically, there are large round or polygonal cells with round central nucleus and abundant cytoplasm with characteristic rod-shaped Reinke crystals in 25% of cases.

As imaging findings cannot differentiate benign from malignant tumors, orchiectomy is often performed.
Case References
  1. Vinay Kumar, Abul K. Abbas y Nelson Fausto. Spanish Version of the original English work of  Robbins and Cotran Pathologic Basis of Disease, 7th edition. Copyright 2005 Elseviere España, S.A.. Genova, 17,3.º Madrid. España. ISBN: original edition: 0-7216-0187-1. ISBN:84-8174-841-2
  2. Carol M. Rumack, Stephanie R. Wilson, William Charboneau, Deborah Levine. Diagnostic Ultrasound, 4th edition. Copyright © 2011 By Mosby, Inc., an affiliate of Elsevier Inc. 1600 John F. Kennedy Blvd. Ste 1800 Philadelphia, PA 19103-2899. ISBN: 978-0-323-05397-6
  3. Tumors and Lesions of the Testis Tumorlike: Radiologic-Pathologic Correlation.  Paula J. Woodward, Roya Sohaey, Michael J. O’Donoghue and Douglas E. Green.  September 2002 RadioGraphics 22:189–216
  4. US–MR Imaging Correlation in PathologicConditions of the Scrotum  Woojin Kim, Mark A. Rosen,  Jill E. Langer, Marc P. Banner, Evan S. Siegelman, Parvati Ramchandani.  December 2007 RadioGraphics 27:1239–1253.
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