all important factors in making the appropriate diagnosis. Leukemia Primary leukemia of the testis is rare. However, due to the presence of blood-testis barrier, chemotherapeutic agents are unable to reach the testis, hence in boys with acute lymphoblastic leukemia, testicular involvement is reported in 5% to 10% of patients, with the majority found during clinical remission. The sonographic appearance of leukemia of the testis can be quite varied, as the tumors may be unilateral or bilateral, diffuse or focal, hypoechoic or hyperechoic. These findings are usually indistinguishable from that of the lymphoma [Fig. 9]. Epidermoid cyst Epidermoid cysts, also known as keratocysts, are benign epithelial tumors which usually occur in the second to fourth decades and accounts for only 1–2% of all intratesticular tumors. As these tumors have a benign biological behavior and with no malignant potential, preoperative recognition of this tumor is important as this will lead to testicle preserving surgery (enucleation) rather than unnecessary orchiectomy. Clinically, epidermoid cyst cannot be differentiated from other testicular tumors, typically presenting as a non-tender, palpable, solitary intratesticular mass. Tumor markers such as serum beta-human chorionic gonadotropin and alpha-feto protein are negative. The ultrasound patterns of epidermoid cysts are variable and include: A mass with a target appearance, i.e. a central hypoechoic area surrounded by an echolucent rim; An echogenic mass with dense acoustic shadowing due to calcification; A well-circumscribed mass with a hyperechoic rim; Mixed pattern having heterogeneous echotexture and poor-defined contour and An onion peel appearance consisting of alternating rings of hyperechogenicities and hypoechogenicities. However, these patterns, except the latter one, may be considered as non-specific as heterogeneous echotexture and shadowing calcification can also be detected in malignant testicular tumors. The onion peel pattern of epidermoid cyst [Fig. 10] correlates well with the pathologic finding of multiple layers of keratin debris produced by the lining of the epidermoid cyst. This sonographic appearance should be considered characteristic of an epidermoid cyst and corresponds to the natural evolution of the cyst. Absence of vascular flow is another important feature that is helpful in differentiation of epidermoid cyst from other solid intratesticular lesions. Extratesticular tumors Although most of the extratesticular lesions are benign, malignancy does occur; the most common malignant tumors in infants and children are rhabdomyosarcomas. Other malignant tumors include liposarcoma, leiomyosarcoma, malignant fibrous histiocytoma and mesothelioma. Rhabdomyosarcoma Rhabdomyosarcoma is the most common tumor of the lower genitourinary tract in children in the