Segmental Testicular Infarction
Sonographic Findings and Pathologic Correlation
Department of Radiology, Beaumont Health System, Royal Oak, Michigan USA; and Oakland University, William Beaumont School of Medicine, Rochester, Michigan USA
Address correspondence to Syed Zafar Jafri, MD, Department of Radiology, Beaumont Health System, 3601 W 13 Mile Rd, Royal Oak, MI 48071 USA. E-mail: firstname.lastname@example.org
Segmental testicular infarction can mimic testicular carcinoma on sonography and can lead to unnecessary orchiectomy. This case series describes and correlates sonographic and histologic findings of 7 pathologically proven segmental testicular infarction cases. Segmental testicular infarction should be suspected on sonography when a geographic lesion with low or mixed echogenicity has absent or near-absent flow in a patient with scrotal pain. A hyperechoic rim and peripheral hyperemia correspond to interstitial hemorrhage and inflammatory changes. As an infarct evolves, it becomes more discrete and hypoechoic as ghost outlines replace seminiferous tubules. Follow-up or contrast-enhanced magnetic resonance imaging or sonography can increase diagnostic confidence in suspected cases and prevent unnecessary orchiectomy.
Segmental testicular infarction is a localized infarct of the testis. Case reports have described it in relation to epididymoorchitis, trauma, sickle cell disease, polycythemia, hypersensitivity angitis, intimal fibroplasia of the testicular artery, and as a complication of recent surgery.1–5 Most cases, however, have no clear etiology and are considered idiopathic.6
Scrotal pain is the predominant presenting symptom. Consequently, sonography with color Doppler is the initial imaging modality of choice. Wedge-shaped or round hypoechoic intratesticular lesions with absent or low flow on color Doppler sonography have been most often described in the literature.6–9 Perilesional hyperemia has also been described. Contrast-enhanced magnetic resonance imaging and sonography can increase confidence in the diagnosis of segmental testicular infarction by showing perilesional rim enhancement.10 In many cases, however, a definitive diagnosis is made histologically only after orchiectomy.
A few case series and case reports have been published, but there is a paucity of radiologic-pathologic correlation in the literature. To our knowledge, this is the most extensive clinical-pathologic and radiologic-pathologic series to date. The purpose of this series is to describe the sonographic features of pathologically proven cases of segmental testicular infarction and present the associated histologic findings.
Materials and Methods
This study was a single-center retrospective case series. The Human Investigations Committee reviewed and approved the study method. Cases were identified through a search of testicular pathology records between January 1, 1999, and December 31, 2010. Only cases with histologically proven segmental testicular infarction and pre-operative scrotal sonographic examinations were included in this study.
Available images were reviewed in consensus by 2 board-certified radiologists. The radiologists were not blinded to the final diagnosis. Sonographic characteristics evaluated included testicle side, size, location within the testicle, shape, echogenicity and presence of a color Doppler signal, hyperemic rim, and hyperechoic rim. Pathologic specimens were reviewed by a single board-certified pathologist. Sonographic and histologic images were reviewed independently within each department and concurrently in joint review sessions.
A total of 10 histologically proven cases of segmental testicular infarction were identified over the 12-year period. Sonograms for 3 cases were not available for review. The ages of the cases ranged between 18 and 77 years with a mean of 41 years. All cases were unilateral at the time of presentation. Multiple foci of infarction were reported in 1 patient.
Associated histories of remote torsion, mumps orchitis, and renal cell carcinoma were present in 1 case each. One patient with a previously unremarkable medical history had a diagnosis of granulomatous vasculitis based on the testicular pathologic findings. A patient with a family history of factor V Leiden deficiency was subsequently found to test negative for that disease but was found to have elevated levels of anticardiolipin immunoglobulin M antibodies. The remaining 5 cases were considered idiopathic.
Sonographic reports raised the suspicion of a neoplastic process or stated that a neoplastic process could not be excluded in 7 of 7 cases in which images were available for review. Infarction was mentioned as a diagnostic consideration in 2 studies, and follow-up study was recommended for one of these, although not performed.
The age of the infarct at histologic examination was determined by the presence of specific findings. Acute infarcts had findings of acute coagulative necrosis, red cell and fibrin extravasation, and mild or no thickening of the basement membranes of the seminiferous tubules. Subacute infarcts had seminiferous tubules composed mostly of Sertoli cells, early maturation arrest, and variable but generally markedly thickened basement membranes. Chronic infarcts showed foci of entirely sclerosed seminiferous tubules with hyalinized interstitial fibrosis.
The patient presented with a 1-day history of left testicular pain. Sonography performed on the same day showed a round lesion with heterogeneous echogenicity in the superior pole of the left testicle. A hyperechoic rim and perilesional hyperemia were present (Figure 1A). A scant color Doppler signal was shown within the lesion.
Segmental Testicular Infarction
Orchiectomy was performed on the same day. Red blood cells and neutrophils were noted at the periphery of the lesion on representative histologic sections, relating to extravasation from interstitial hemorrhage (Figure 1B). Ischemic changes, neutrophils, and edema were noted centrally within the lesion. An early organizing thrombus with lines of Zahn was present in a feeding vessel. Histologic findings were consistent with an acute segmental testicular infarct.
The patient presented with the sensation of a left testicular mass for less than 1 week. His medical history was notable for testicular torsion 7 years earlier. Sonography was performed on the same day and showed a large round discrete hypoechoic area in the mid to lower pole of the left testicle extending to the periphery (Figure 2A). There was no hyperechoic rim. Interrogation with color Doppler sonography was not performed.
Ancient segmental testicular infarct in a 34-year-old man. A, Grayscale sonogram showing a discrete hypoechoic area in the mid to lower pole of the left testicle. B, Hematoxylin-eosin–stained section showing outlines of completely hyalinized acellular tubules in the bottom half of the image with a band of viable tubules above.
The patient underwent left orchiectomy 6 days after presentation. There was a well-defined focal area composed of completely sclerosed seminiferous tubules and hyalinized interstitial fibrosis. Adjacent testicular parenchyma showed viable seminiferous tubules with evidence of spermatogenesis (Figure 2B). These findings were consistent with an ancient segmental testicular infarct.
The presenting symptom was 3 days of left testicular pain. Initial scrotal sonography performed on the day of presentation showed an irregularly shaped area of heterogeneous echogenicity in the inferior pole of the left testicle. The lesion was hypovascular with a single flow signal seen centrally on power Doppler sonography. A mild hyperemic rim was present, but there was no hyperechoic rim (Figure 3A).
Images from a 22-year-old man with left testicular pain. A, Power Doppler sonogram showing an irregular heterogeneous lesion in the inferior pole of the left testicle with a hyperemic rim and intralesional flow. B, Follow-up color Doppler sonogram showing the lesion to be more discrete, again with intralesional flow. C, Hematoxylin-eosin–stained section showing a very acute phase of testicular infarction on the left, subacute and chronic ischemic changes in the middle, and uninvolved testicular parenchyma on the right.
Orchiectomy was performed 29 days after initial presentation. Representative histologic sections showed acute ischemic necrosis centrally within the lesion with scattered areas of viable seminiferous tubules (Figure 3C). An acute organizing thrombus was present with evidence of organization and recanalization. Peripherally, chronic ischemic changes were also noted, including seminiferous tubules with thickened basement membranes and partial loss of germ cells. It was postulated that the organized and recanalized thrombus led to reestablishment of some degree of vascular flow, resulting in a subsequent increased intralesional Doppler signal.
The patient’s history was not available for review. Scrotal sonography showed a discrete round lesion of heterogeneous echogenicity in the inferior pole of the right testicle (Figure 4A). There was no echogenic or hyperemic rim. A color Doppler signal was mildly present at the periphery of the lesion.
Images from an 18-year-old man, history unknown. A, Color Doppler sonogram showing a heterogeneous round lesion in the inferior pole of the right testicle with mild peripheral flow. B, Hematoxylin-eosin–stained section showing a large area of circumscribed infarction with central organizing hemorrhage and peripheral fibrosis containing completely sclerosed seminiferous tubules (arrow). Normal testicular parenchyma is shown on the left.
Histologic examination from a right orchiectomy specimen obtained 7 days after sonography showed seminiferous tubules with variably thickened basement membranes, including foci of completely sclerosed seminiferous tubules, which were associated with chronic granulation tissue with hemosiderin deposition, fibrosis, and a small microscopic focus of organizing hemorrhage. These features likely accounted for the heterogeneous echogenicity, and the discreteness of the lesion was due to the presence of a zone of pale fibrosis peripherally (Figure 4B).
The patient presented with left testicular pain of unknown duration. Scrotal sonography performed on the day of presentation revealed a large round hypoechoic lesion in the inferior pole of the left testicle (Figure 5A). There was no echogenic rim or peripheral hyperemia.
Segmental Testicular Infarction
Ancient segmental testicular infarct in a 57-year-old man. A, Grayscale sonogram showing a round hypoechoic lesion in the inferior pole of the left testicle. B, Hematoxylin-eosin–stained section showing normal testicular parenchyma on the left and a large area of eosinophilic hyalinized fibrosis on the right, consistent with an ancient infarct.
Orchiectomy was performed 22 days after initial presentation. Histologic sections showed an area of chronic infarction composed of extensive hyalinized fibrosis with some peripheral areas showing outlines of completely sclerosed seminiferous tubules. Rare scattered viable tubules were seen in the area of infarction. Blood vessels were also seen coursing through the lesion but displayed marked intimal thickening and fibroplasia (Figure 5B).
The patient presented to the emergency department with a 1-day history of left testicular pain. Scrotal sonography performed the same day showed a round lesion with heterogeneous echogenicity in the superior pole. An echogenic rim was not present, but there was marked peripheral hyperemia. A mild color Doppler signal was noted internally (Figure 6A).
Images from a 47-year-old man with left testicular pain. A, Color Doppler sonogram showing a heterogeneous lesion in the superior pole of the left testicle with marked peripheral hyperemia and rare intralesional flow. B, Follow-up study showing decreased peripheral hyperemia. The lesion appears more discrete and hypoechoic. C, Hematoxylin-eosin–stained section showing acute infarction of seminiferous tubules in the top right half of the image with associated interstitial edema and hemorrhage. The bottom left portion of the image shows subacute and chronic ischemic changes in seminiferous tubules. An organizing thrombus (arrow) is shown just outside area of acute infarction.
Follow-up sonography performed 26 days after the initial study showed persistent but decreased peripheral hyperemia and absence of a color Doppler signal within the lesion. The lesion now appeared more well defined and hypoechoic (Figure 6B).
Thirty-three days after initial presentation, the patient underwent left orchiectomy. Representative histologic sections showed subacute and chronic ischemic changes peripherally with an area of acute ischemic necrosis centrally. Organizing thrombi were seen in the surrounding vasculature (Figure 6C). The area of central ischemic necrosis appeared relatively new, of likely less than 2 to 3 days’ duration, and was not seen on the sonographic examination performed 7 days previously.
The patient presented with 2 days of testicular pain. Scrotal sonography on the day of presentation showed an irregularly shaped hypoechoic lesion in the inferior pole of the right testicle. The lesion was hypovascular on Doppler interrogation. A hyperechoic rim and perilesional hyperemia were present (Figure 7, A and B).
Granulomatous vasculitis in a 29-year-old man. A, Grayscale sonogram showing an irregular hypoechoic lesion in the inferior pole of the right testicle with a hyperechoic rim. B, Color Doppler sonogram showing perilesional hyperemia. C, Hematoxylin-eosin–stained section showing an irregularly shaped pale area of subacute and chronic infarction with surrounding lobular aggregates of viable seminiferous tubules. Centrally within this area is a small focus of acute infarction (arrow). Inset, Peripheral medium-sized artery with vasculitis.
Orchiectomy performed 36 days after presentation showed neovascularity peripherally surrounding an area of subacute and chronic infarction. Embedded within the region of subacute and chronic infarct was a small area of hyperacute infarction with red cell extravasation (Figure 7C). The pathologic findings represented disease evolution since the time of the radiologic examination.
Segmental testicular infarction affects patients in a wide age range. The most common presenting symptom is acute testicular pain. Consistent with other studies, most cases in this series were of idiopathic etiology. As shown here, however, segmental testicular infarction may be related to prior testicular torsion or may be a symptom of an underlying systemic process such as a vasculitis or hypercoagulable disorder. Consequently, segmental testicular infarction should be considered in the differential diagnosis in patients from whom such histories can be elicited.
The sonographic appearance of the segmental testicular infarctions shown in this case series supports the findings of previous studies. The cases in this series were depicted as peripherally located, round, or irregularly shaped lesions of low or mixed echogenicity. Flow within the lesions is typically absent or minimal on color Doppler interrogation.
The echogenicity and discreteness of the lesion on sonography appear to relate to the age of the infarct. In the acute phase, heterogeneous echogenicity was most often seen and, as shown in case 1, corresponded to the mixed presence of edema, hemorrhage, and scattered viable and nonviable testicular parenchyma within the area of infarction. Similar to previous reports, short-term follow-up sonography performed in 2 cases showed that the infarcted areas became progressively more homogeneously hypoechoic and discrete with time.10 The conspicuous appearance and hypoechogenicity seen in chronic/ancient infarcts corresponded well with the homogeneous areas of sclerosed seminiferous tubules and hyalinized interstitial fibrosis seen on histologic specimens. Of note, cases of chronic infarcts presented in this series did show a rare intralesional Doppler signal. Whether these rare vessels represent neovasculature as hypothesized in other studies or residual vascularity cannot be determined.10
A hyperechoic rim and perilesional hyperemia were shown in several cases in this series, similar to other reported cases. In case 1, the hyperechoic rim corresponded to a peripheral rim of red blood cell and neutrophil extravasation secondary to interstitial hemorrhage seen on histologic specimens. The inflammatory changes in the perilesional vasculature leading to the extravasation are suspected to account for the associated observed perilesional hyperemia on sonography. Prior studies have speculated that perilesional hyperemia may reflect bundling of perilesional parenchymal vessels, but it was not shown.7
Bertolotto et al10 theorized that the perilesional rim enhancement observed on contrast-enhanced sonography represents changes related to subacute infarction. Contrast-enhanced sonography was not performed in any of the cases in this series. Areas of subacute segmental testicular infarction, however, were captured on histologic specimens and indeed showed evidence of granulation tissue and neovasculature.
This series was limited by its small sample size. The delay between imaging and pathologic evaluation was also a limiting factor, as only in 1 case were the sonographic examination and orchiectomy performed the same day. The histologic findings and clinical symptoms were correlated to understand the ages of the infarcts. These findings were extrapolated to the sonographic appearances and correlations attempted, and the findings were concordant.
Differentiating a segmental testicular infarct from other conditions on sonography is difficult. Knowledge of the dynamic sonographic appearance of a segmental testicular infarct and the histologic basis of these findings may help with diagnosis. Contrast-enhanced magnetic resonance imaging and sonography can increase confidence in the diagnosis in suspected cases. On T1-weighted images, a segmental infarct may appear isointense to testicular parenchyma or may show foci of high signal intensity if hemorrhagic. Although variable, the signal on T2-weighted images usually appears low in the area of infarction. Rim enhancement may be present on gadolinium-enhanced images.11,12 Similarly, contrast-enhanced sonography may show perilesional enhancement during the subacute phase. Identification of lobular morphologic characteristics of ischemic testicular lobules and centripetal testicular arteries may also help distinguish segmental a testicular infarct from a hypovascular tumor.10
Segmental testicular infarction should be suspected on sonography when a geographic hypoechoic or heterogeneous area has absent or near-absent flow as shown by the color Doppler signal in a patient with scrotal pain. An acute segmental infarct may show a hyperechoic rim or peripheral hyperemia corresponding to interstitial hemorrhage and inflammatory changes at the periphery of the infarct. As the infarct evolves, it may become more discrete and homogeneously hypoechoic as the seminiferous tubules are replaced by ghost outlines. Intralesional flow is reduced but may be shown. Segmental testicular infarction is an important consideration when clinically appropriate to prevent unnecessary surgical intervention. Although the cases in our series did not have other imaging evaluation, increased confidence in the diagnosis of segmental testicular infarction may be possible by using contrast-enhanced sonography or magnetic resonance imaging.10–12
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