Summary
A 37-year-old man presented with a complaint of a rapidly enlarging testicular mass that had occurred over a 2-week period. There was no reported history of antecedent trauma, pain, or discomfort.
On physical examination, the patient was found be a healthy man with no palpable abdominal or inguinal masses. Upon examination of the left testicle, a moderate testicular mass was palpated. The contralateral right testicle and epididymis were normal.
Imaging Findings
Ultrasound revealed bilateral micro lithiasis of the testicles. The left testicle was found to have an underlying 4-cm solid, hypoechoic, mildly lobulated soft tissue mass that was most suggestive of a neoplasm in a sea of microlithiasis (Figure 1). CT of the abdomen was performed and showed a few small retroperitoneal lymph nodes of moderate suspicion (Figure 2).
Figure 1.(A) Sagittal ultrasound (US) image reveals a lobulated hypoechoic mass within the left testicle and peripheral microlithiasis. (B) Doppler US interrogation shows flow within the seminoma on this sagittal US image of the contralateral (right) testicle. (C) Sagittal US image of the contralateral (right) testicle depicts microlithiasis on a background of normal parenchyma.
Figure 2.This contrast-enhanced CT scan shows a retroperitoneal lymph node anterior to the left psoas muscle.
The specimen radiograph was quite extraordinary and confirmed innumerable microcalcifications throughout the specimen (Figure 3). Surgical pathology confirmed a classic seminoma of the left testicle. Associated pathologic findings indicated multiple foci of small, scattered, round calcifications (Figures 4 and 5). The differential diagnosis of an intratesticular mass includes neoplasm, especially given the patient's clinical history. However, an inflammatory or infectious process (such an abscess) or a granulomatous process (such as a sarcoid) may also be diagnostic possibilities. Correlation with appropriate clinical history would be helpful in differentiating among these entities.
Figure 3.The specimen radiograph of the left orchiectomy specimen reveals innumerable microliths.
Figure 4.This photograph of the bisected specimen reveals the testicular mass.
Figure 5.(A) Hematoxylin and eosin (H&E)-stained section shows a microlith surrounded by seminiferous tubules. (B) This H&E stained section indicates seminoma of the classic type.
Diagnosis
Testicular microlithiasis (TM) and classic seminoma
Discussion
It is estimated that in the United States in 2007 there were approximately 7920 newly diagnosed cases of testicular cancer, and approximately 380 men died of this disease.[1] In the 15- to 35-year-old age group, this is the most common cancer in young men and is one of the most responsive to treatment. Testicular cancer remains one of the most common causes of cancer mortality in young men. The only other causes of death that supersede testicular cancer in young men are trauma and suicide.
In 1970, Priebe and Garret[2] first described testicular microlithiasis in the X-ray of a healthy 4-year-old boy. In 1982, Ikinger et al[3] identified the association of microcalcifications with testicular cancer. Subsequent description via ultrasonography was described for the first time in 1987 by Doherty et al.[4] In 1988, Martin et al[5] reported the association of ultrasound diagnosis of microlithiasis with associated testicular neoplasia.
Testicular microlithiasis is an abnormality of uncertain etiology that is characterized pathologically by the accumulation of smooth round lamellated bodies within the seminiferous tubules.[6] The microliths are typically scattered diffusely throughout the parenchyma, and range in size from 1 to 3 mm. They typically do not exhibit shadowing, and symmetric involvement has been noted. Two classic categories of microlithiasis have been described. Classic testicular microlithiasis (CTM) is defined as having =5 microliths within a single ultrasound image.[7] This is in contradistinction to limited microlithiasis (LTM), which doesn't fit into this arbitrary classification.
The prevalence of TM in a referred population has been reported to be approximately 0.6%. A study of the prevalence of microlithiasis in an asymptomatic screening population illustrated that TM occurs in approximately 5% of asymptomatic men.[8] The association of microlithiasis with testicular cancer in select series has been as high as 40%.[9]
There are 2 histologic subtypes of microlithiasis reported. One type thought to be secondary to rapid cell turnover is a hematoxylin body consisting of amorphous calcified debris. This subtype is thought to have a greater association with germ cell tumor.[10] The second subtype is the classically described subtype, which is used throughout the literature and is composed of laminated calcifications that are reported to be associated with cryptorchid testes, germ cell tumors, and otherwise normal testicles. The pathogenesis of TM is unclear. Sertoli cells are responsible for the phagocytosis of intratubular debris. The microcalcifications are thought to result from a defect in this process. It is not known whether microlithiasis leads to subsequent tumor development or if it is part of a spectrum of abnormalities that eventually leads to carcinogenesis.[9]
There are a number of entities associated with TM, including cryptorchidism, Down's syndrome, infertility, pulmonary microlithiasis, and germ cell tumor. The known associations of microcalcifications in the presence of other known malignancies (such as breast cancer and thyroid cancer) make the association with testicular cancer valid. Intraepithelial germ cell neoplasia (which is also known as carcinoma in situ [CIS]), from which testicular cancer develops, has also been associated with TM. One series reported a 40-fold increase in CIS in men with bilateral TM microlithiasis compared with those patients without TM.[11] An additional study reported a high prevalence of CIS in a subset of patients with known microlithiasis and a contralateral testicular carcinoma.[12] Given the 50% probability that CIS will eventually progress into cancer, it is reasonable to perform biopsy of the contralateral testicle in patients with known microlithiasis who are already undergoing a radical orchiectomy for testicular carcinoma.[10]
Interestingly, Peterson and coworkers refute the theory that microlithiasis is associated with subsequent development of cancer in an asymptomatic screening population.[8] Their study reported an increased incidence in African American men, a population not at increased risk for testicular cancer in the absence of microlithiasis. Additionally, the rate of carcinoma found in association with TM did not exceed the rate at which it was found in patients who did not have TM.[8]
Despite the controversy, enough of an association has been established that physical examination with annual screening sonography is recommended. Other authors have recommended that an initial chest and abdominal CT be performed when TM is diagnosed, with continued annual sonographic surveillance.[13] In a screened population, in addition to excluding a focal mass, clinicians should be alerted to subtle alteration in the echotexture of the testicular parenchyma, which may suggest the early manifestations of germ cell neoplasia.
Conclusion
Testicular cancer is the most common cancer in young men aged 15 to 35 and is typically responsive to treatment. Although testicular microlithiasis is relatively rare, it is historically associated with testicular cancer. Controversy still exists on recommendations for future follow-up of incidental testicular microlithiasis. This radiologic case reinforces the importance of remaining cognizant of the association between the 2 conditions. Diligent sonographic interrogation of the testes in the setting of microlithiasis is essential, as illustrated by this case.
References
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