Ultrasound of the Acute Scrotum

Phebe Chen, MD, Susan John, MD


Appl Radiol. 2006;35(3):8-17. 

In This Article


Testicular and paratesticular tumors can occur in all age groups but are an uncommon cause of acute scrotal pain (10%).[5] Testicular tumors are more likely malignant, while extratesticular tumors are more likely benign. In general, palpable masses are more likely to be malignant than are nonpalpable masses.[4] The role of US is to distinguish intratesticular from extratesticular lesions. Approximately 90% to 95% of testicular tumors are germ cell tumors, most commonly seminomas. Nonseminomatous germ cell tumors are usually of mixed cell types. Other testicular tumors include gonadal stromal tumors, lymphoma, leukemia, and metastases.[2] The differential diagnosis of focal testicular mass includes hematoma, abscess, focal orchitis, infarction, and granulomatous disease. Color Doppler imaging can help to differentiate such abnormalities from tumor, but distinction may be difficult when tumor presents as generalized testicular enlargement without focal mass. In up to 15% of patients, signs and symptoms caused by metastatic disease are the first indication of testicular tumor. Occasionally, the primary tumor may have undergone spontaneous regression and appear as an irregular scar or calcification without a definite mass.[6]

The adenomatoid tumor of the epididymis is the most common extratesticular tumor in adults. Adenomatoid tumor is a benign hamartoma that favors the epididymal tail.[11] Other extratesticular tumors include lipomas, leiomyomas, lymphangiomas, sarcomas, and metastases. Malignant lesions to the scrotal wall are usually of epididymal origin. The most common malignant paratesticular tumor in infants and children is rhabdomyosarcoma, which is associated with a better prognosis than rhabdomyosarcoma found elsewhere in the genitourinary tract.

Testicular microlithiasis (TM) is defined as multiple (>5) echogenic nonshadowing 2- to 3-mm foci randomly scattered throughout the testicular parenchyma (Figure 13). The number, distribution, and laterality of the foci varies. Diagnosis requires high-frequency US transducers.[12] Testicular microlithiasis is associated with cryptorchidism, infertility, pulmonary alveolar microlithiasis, and intratubular germ cell neoplasia. Eighteen percent to 75% of patients are at risk for testicular cancer, primarily nonseminomas.[4] The relation of the number of calcifications to cancer risk has not been well established, but in the absence of a focal mass, annual follow-up is recommended in all patients with TM.[12] Fibrous septae in normal testes can mimic the foci of TM, but normal septae disappear when scanned at a 90º angle.

Testicular microlithiasis. Note multiple punctate highly echogenic foci scattered throughout the testicle.


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