Troubleshooting Tips for Diagnosing Complex Fetal Genitourinary Malformations.

Fetal genitourinary anomalies can present a diagnostic challenge for the radiologist. The absence of a normally located kidney may represent agenesis or be secondary to a fusion or migration abnormality. A dilated renal pelvis should prompt evaluation for a specific cause, including ureteropelvic junction obstruction, reflux, or an obstructed duplicated system. Cystic parenchymal changes are characteristic of a multicystic dysplastic kidney but may also be seen in obstructive cystic dysplasia. There are numerous causes of megacystis including chromosomal (trisomy 18 syndrome), obstruction (posterior urethral valves, urethral atresia), or muscular dysfunction (prune belly syndrome, megacystis microcolon intestinal hypoperistalsis syndrome). Important mimics of a large bladder include hydrocolpos and urogenital sinus or cloacal malformation. Complications of genitourinary malformations are common and include oligohydramnios, urinary ascites, and urinoma. Making an accurate diagnosis often requires additional US views beyond those obtained in the standard fetal survey and occasionally performing fetal MRI. The appropriate use of orthogonal T2-weighted sequences, in conjunction with diffusion-weighted images for evaluation of the kidneys and gradient-recalled-echo sequences for evaluation of T1-hyperintense meconium in the colon, can play an integral role in diagnosis. Accurate diagnosis of fetal genitourinary malformations is vital to direct patient counseling and pregnancy management as outcomes are highly variable. Some conditions can be surgically corrected quite simply, some require multiple complex procedures, and some are lethal. The authors offer troubleshooting tips to narrow the differential diagnosis for four observations: unilateral absent kidney, dilated renal pelvis, cystic renal parenchyma, and megacystis and its mimics. ©RSNA, 2023 Test Your Knowledge questions are available in the Online Learning Center.

Neurological and clinical outcomes in infants and children with a fetal diagnosis of asymmetric ventriculomegaly, interhemispheric cyst, and dysgenesis of the corpus callosum.

OBJECTIVE: Advances in prenatal imaging have facilitated improvements in the fetal diagnosis of congenital anomalies. Asymmetric ventriculomegaly, interhemispheric cyst, and dysgenesis of the corpus callosum (AVID) is a constellation of congenital anomalies reported in fetal imaging. However, few data are available regarding postnatal outcomes of infants and children with a fetal diagnosis of AVID. The authors sought to report the neurodevelopmental outcomes of patients diagnosed with AVID before birth at a single institution. METHODS: An institutional fetal imaging database was queried to identify cases with ventriculomegaly, interhemispheric cyst, and dysgenesis of the corpus callosum over a 10-year study period from 2000 to 2019. Overall, 41 maternal-infant dyads who met imaging criteria for AVID were identified; medical records were reviewed for prenatal variables including gestational age at birth, perinatal complications including fetal demise, and postnatal variables including demographics, mortality, hydrocephalus diagnosis and management, epilepsy, and neurodevelopmental outcomes at 2 years or the last follow-up. RESULTS: Among 41 patients, 25 (61%) were male. A slight majority of patients (55%) were born before 36 weeks of gestational age, and 27 patients (68%) were delivered via cesarean section because their head size precluded vaginal delivery. There were 8 incidences of fetal demise, 1 pregnancy was terminated, and 32 patients were born alive. Neonatal or early infant death occurred in 5 patients. Two children died during follow-up after the neonatal period (ages 7 months and 7 years). Twenty-six children survived to at least the 2-year follow-up, all of whom required treatment for hydrocephalus. Of those 26 children, 12 (46%) had a diagnosis of epilepsy, 14 (54%) could sit independently, 4 (16%) were in mainstream school, 16 (62%) had expressive language, and 7 (28%) had near-normal development without seizures. CONCLUSIONS: Among 41 maternal-fetal dyads with AVID, a majority of children survived to the 2-year follow-up, although all developed hydrocephalus. Many continued to have seizures, but expressive language use, attendance at mainstream school, and near-normal development without seizures were not infrequent. These data are critical for prenatal counseling and to establish the natural history of a diagnosis with limited outcome data.

Fat-containing Retroperitoneal Lesions: Imaging Characteristics, Localization, and Differential Diagnosis.

The complex anatomy of the retroperitoneum is reflected in the spectrum of neoplastic and nonneoplastic conditions that can occur in the retroperitoneum and appear as soft-tissue masses. The presence of fat within a retroperitoneal lesion is helpful in refining the differential diagnosis. Fat is easily recognized because of its characteristic imaging appearance. It typically is hyperechoic at ultrasonography and demonstrates low attenuation at computed tomography (-10 to -100 HU). Magnetic resonance imaging is a more ideal imaging modality because it has better soft-tissue image contrast and higher sensitivity for depicting (a) microscopic fat by using chemical shift imaging and (b) macroscopic fat by using fat-suppression techniques. Whether a lesion arises from a retroperitoneal organ or from the soft tissues of the retroperitoneal space (primary lesion) is determined by examining the relationship between the lesion and its surrounding structures. Multiple imaging signs help to determine the organ of origin, including the "beak sign," the "embedded organ sign," the "phantom (invisible) organ sign," and the "prominent feeding artery sign." Adrenal adenoma is the most common adrenal mass that contains microscopic fat, while myelolipoma is the most common adrenal mass that contains macroscopic fat. Other adrenal masses, such as pheochromocytoma and adrenocortical carcinoma, rarely contain fat. Renal angiomyolipoma is the most common fat-containing renal mass. Other fat-containing renal lesions, such as lipoma and liposarcoma, are rare. Fatty replacement of the pancreas and pancreatic lipomas are relatively common, whereas pancreatic teratomas are rare. Of the primary retroperitoneal fat-containing lesions, lipoma and liposarcoma are common, while other lesions are relatively rare. (©)RSNA, 2016.

Holoprosencephaly: a survey of the entity, with embryology and fetal imaging.

Structural malformations of the brain are an important cause of childhood mortality and morbidity, with the latter having long-term financial and psychosocial implications for the affected child and family. Holoprosencephaly (HPE) is a severe brain malformation characterized by abnormal cleavage of the prosencephalon in the 5th gestational week. Aprosencephaly and atelencephaly occur earlier because of failure in the formation of the prosencephalon and telencephalon, respectively. The HPE holoprosencephaly spectrum classically includes alobar, semilobar, and lobar forms, although there are no clear-cut defining features. The middle interhemispheric variant (MIH), also known as syntelencephaly, is classified as a variant of HPE holoprosencephaly with midline interhemispheric fusion. Other conditions sometimes included in the spectrum of HPE holoprosencephaly include septo-optic dysplasia (SOD); "minimal" HPE holoprosencephaly , which is associated with subtle craniofacial malformations and mild developmental delay; and microform HPE holoprosencephaly , which by definition excludes brain involvement. The focus of this article will be on the spectrum of findings visible in fetal manifestation of the HPE holoprosencephaly spectrum. Brain embryology; the imaging characteristics, epidemiology, and embryology of HPE; and the more common associated anomalies, particularly those of the face ("the face predicts the brain") are reviewed. Recognition of these anomalies is important for accurate parental counseling, since the prognosis is poor but not invariably lethal; children with the milder forms may live well into their teens with severe developmental delays, endocrine dysfunction, and disrupted homeostasis. Available data on outcome in surviving children are summarized. Illustrative fetal ultrasonographic and magnetic resonance images are presented with clinical, autopsy, and postnatal imaging correlation.

Cloacal malformation: embryology, anatomy, and prenatal imaging features.

Cloacal malformation is a rare but important anomaly. Prenatal diagnosis is possible with knowledge of the distinctive imaging features. The purpose of this case series is to illustrate characteristic prenatal sonographic and magnetic resonance imaging features of cloacal malformation using imaging from 6 cases seen at a single academic center to augment published data. The imaging feature common to all cases was a central cystic pelvic mass containing a characteristic fluid-fluid level. Additional anomalies include uterine and vaginal duplication, hydronephrosis, and lumbosacral anomalies. Prenatal magnetic resonance imaging showed the absence of the normal T1-hyperintense meconium-filled rectum in all cases. Prenatal diagnosis may affect immediate neonatal care (eg, immediate drainage of hydrocolpos) with an ultimate improved outcome.

Testicular epidermoid cysts: sonographic features with clinicopathologic correlation.

OBJECTIVE: The purpose of this series was to describe the sonographic features of intratesticular epidermoid cysts with clinicopathologic correlation. METHODS: A retrospective review of the sonographic features of all intratesticular epidermoid cysts within the radiologic pathology archive of the Armed Forces Institute of Pathology with correlation with clinical, surgical, and pathologic data was performed. On sonograms, intratesticular epidermoid cysts were evaluated for shape, borders, and the presence of characteristic features, including alternating hypoechoic and hyperechoic rings, mural calcifications, and echogenic central core. Color Doppler imaging was evaluated for the presence of internal flow. RESULTS: Of 21 cysts seen in 20 male patients (mean age, 24 years; range, 11-52 years), the most common finding was mural calcifications, which were seen in 18 lesions (86%). Concentric rings of alternating echogenicity were shown in 13 lesions (62%), and 7 cysts (33%) had an echogenic central core. No cysts showed internal vascularity. CONCLUSIONS: Testicular epidermoid cysts are uncommon solid-appearing testicular masses that usually present as palpable masses and are benign. Knowledge of the sonographic and pathologic features may help differentiate these lesions from malignancy and possibly prevent unnecessary orchiectomy.

The cavum septi pellucidi: why is it important?

OBJECTIVE: The cavum septi pellucidi (CSP) is routinely imaged in the fetal brain during obstetric sonography; in fact, for well over a decade, assessment of the CSP has been considered part of the required elements of a standard examination of fetal morphology in guidelines developed by multiple specialty societies. Our objective is to present the 4 reasons why all practicing sonologists and sonographers should be familiar with this anatomic structure. METHODS: Prenatal sonograms and magnetic resonance imaging examinations are used to review the following topics: terminology, embryology, and anatomy of the CSP; pitfalls in its identification; and a wide variety of abnormalities (predominantly relating to nonvisualization) associated with the CSP. RESULTS: Embryologic development of the CSP is intimately associated with the corpus callosum (CC); thus, correct identification of the CSP essentially excludes complete agenesis of the CC. Absence of the CSP is associated with an extremely wide spectrum of neuroanatomic malformations: these range from the lethal entities of hydranencephaly and alobar holoprosencephaly; to the potentially serious but nonlethal entities of schizencephaly, porencephaly, basilar encephaloceles, severe hydrocephalus, and the less severe prosencephalic cleavage disorders (including syntelencephaly); to the normal variant, the rare and somewhat controversial entity of isolated septal deficiency. The value of noting that the absent CSP allows diagnosis of very subtle and easily overlooked abnormalities such as septo-optic dysplasia is presented. CONCLUSIONS: Correct recognition of the CSP provides welcome reassurance of proper development of the central forebrain.

Early invasive cervical cancer: CT and MR imaging in preoperative evaluation - ACRIN/GOG comparative study of diagnostic performance and interobserver variability.

PURPOSE: To retrospectively compare diagnostic performance and interobserver variability for computed tomography (CT) and magnetic resonance (MR) imaging in the pretreatment evaluation of early invasive cervical cancer, with surgical pathologic findings as the reference standard. MATERIALS AND METHODS: This HIPAA-compliant study had institutional review board approval and informed consent for evaluation of preoperative CT (n = 146) and/or MR imaging (n = 152) studies in 156 women (median age, 43 years; range, 22-81 years) from a previous prospective multicenter American College of Radiology Imaging Network and Gynecologic Oncology Group study of 172 women with biopsy-proved cervical cancer (clinical stage > or = IB). Four radiologists (experience, 7-15 years) interpreted the CT scans, and four radiologists (experience, 12-20 years) interpreted the MR studies retrospectively. Tumor visualization and detection of parametrial invasion were assessed with receiver operating characteristic curves (with P < or = .05 considered to indicate a significant difference). Descriptive statistics for staging and kappa statistics for reader agreement were calculated. Surgical pathologic findings were the reference standard. RESULTS: For CT and MR imaging, respectively, multirater kappa values were 0.26 and 0.44 for staging, 0.16 and 0.32 for tumor visualization, and -0.04 and 0.11 for detection of parametrial invasion; for advanced stage cancer (> or =IIB), sensitivities were 0.14-0.38 and 0.40-0.57, positive predictive values (PPVs) were 0.38-1.00 and 0.32-0.39, specificities were 0.84-1.00 and 0.77-0.80, and negative predictive values (NPVs) were 0.81-0.84 and 0.83-0.87. MR imaging was significantly better than CT for tumor visualization (P < .001) and detection of parametrial invasion (P = .047). CONCLUSION: Reader agreement was higher for MR imaging than for CT but was low for both. MR imaging was significantly better than CT for tumor visualization and detection of parametrial invasion. The modalities were similar for staging, sharing low sensitivity and PPV but relatively high NPV and specificity.

From the archives of the AFIP: Inflammatory and nonneoplastic bladder masses: radiologic-pathologic correlation.

Although the vast majority of bladder tumors are epithelial neoplasms, a variety of nonneoplastic disorders can cause either focal bladder masses or diffuse mural thickening and mimic malignancy. Some of these entities are rare and poorly understood such as inflammatory pseudotumor, which produces ulcerated, bleeding polypoid bladder masses. These masses may be large and have an extravesical component. Bladder endometriosis manifests as submucosal masses with characteristic magnetic resonance imaging features consisting of hemorrhagic foci and reactive fibrosis. Nephrogenic adenoma has no typical features, and pathologic evaluation is required for diagnosis. Although imaging features of malacoplakia are also nonspecific, characteristic Michaelis-Gutmann bodies are found at pathologic evaluation. The various types of cystitis (cystitis cystica, cystitis glandularis, and eosinophilic cystitis) require pathologic diagnosis. Bladder infection with tuberculosis and schistosomiasis produces nonspecific bladder wall thickening and ulceration in the acute phase and should be suspected in patients who are immunocompromised or from countries where these infections are common. The diagnosis of chemotherapy cystitis and radiation cystitis should be clinically evident, but imaging may be used to determine severity and to assess complications. Extrinsic inflammatory diseases such as Crohn disease and diverticulitis may be associated with fistulas to the bladder and focal bladder wall abnormality. The extravesical findings allow the diagnosis to be made easily. Finally, extrinsic masses arising from the prostate or distal ureter may cause filling defects, which can be confused with intrinsic bladder masses.

From the Archives of the AFIP: neoplasms of the urinary bladder: radiologic-pathologic correlation.

In the United States, primary bladder neoplasms account for 2%-6% of all tumors, with bladder cancer ranked as the fourth most common malignancy. Ninety-five percent of bladder neoplasms arise from the epithelium; the most common subtype is urothelial carcinoma, which accounts for 90% of cases. Squamous cell carcinoma accounts for 2%-15%, with rates varying widely according to geographic location. Adenocarcinoma (primary bladder, urachal, or metastatic) represents less than 2%. Bladder cancer typically occurs in men aged 50-70 years and is related to smoking or occupational exposure to carcinogens. Most urothelial neoplasms are low-grade papillary tumors, which tend to be multifocal and recur but have a relatively good prognosis. High-grade invasive tumors are less common and have a much poorer prognosis. Squamous cell carcinoma and adenocarcinoma occur in the setting of chronic bladder infection and irritation. Mesenchymal tumors represent the remaining 5% of bladder tumors, with the most common types being rhabdomyosarcoma, typically seen in children, and leiomyosarcoma, a disease of adults. Rarer mesenchymal tumors include paraganglioma, lymphoma, leiomyoma, and solitary fibrous tumor. Although imaging findings are not specific for these tumors, patterns of growth and tumor characteristics may allow differentiation. For accurate staging, computed tomography and magnetic resonance imaging are the modalities of choice.

The management of indeterminate incidental findings detected at abdominal CT.

Abdominal computed tomography (CT) scans often have findings that are incidental to the reason the study was ordered. Several recent studies and reviews have addressed how these findings should be managed. This article summarizes current management strategies for several types of lesions that are commonly encountered. Some of these findings can be characterized without additional imaging (including simple renal cyst, angiomyolipoma, hepatic steatosis). Other findings are indeterminate. While some of these indeterminate incidental findings can be ignored based on statistical arguments (for example, a sharply circumscribed homogeneous low-attenuation renal lesion under 1 cm in patients without a predisposition to develop renal cell carcinoma), many may need additional imaging studies to either characterize them or demonstrate stability over time. Adhering to these strategies will hopefully reduce overutilization of imaging services while directing attention to those findings which need diagnostic or therapeutic interventions.

From the archives of the AFIP: a comprehensive review of fetal tumors with pathologic correlation.

Fetal tumors are a diverse group of neoplasms, which are unique in their histologic characteristics, anatomic distribution, and pathophysiology. The biologic behavior of tumors in the fetus may differ dramatically compared with that of the same tumor detected later in life. Teratomas are the dominant histologic type and constitute the majority of both extracranial and intracranial neoplasms. Although often histologically mature, they may prove lethal because of their location and metabolic demands on the fetus. Large solid tumors may lead to cardiovascular compromise and hydrops fetalis. Extracranial teratomas are most commonly located in the sacrococcygeal area, followed by the head and neck, chest, and retroperitoneum. Fetuses with intracranial tumors have a poor prognosis regardless of histologic type. There are, however, two notable exceptions: lipomas and choroid plexus papillomas, both of which have a more favorable outcome. Neuroblastoma is the most common fetal malignancy. It may be either solid or cystic and is more often located on the right side. It typically has favorable biologic markers and stage at presentation. The prognosis for prenatally diagnosed cases is excellent. Other fetal neoplasms include soft-tissue tumors (both benign and malignant), leukemia, mesenchymal hamartoma of the kidney, and liver tumors (hemangioendothelioma, mesenchymal hamartoma, and hepatoblastoma).

Computed tomographic appearance of urachal adenocarcinomas: review of 25 cases.

Twenty-five cases of surgically proven urachal carcinomas were retrospectively reviewed. The radiological archives at the Armed Forces Institute of Pathology were searched for cases of surgically proven urachal carcinomas that had a computed tomographic (CT) scan as a part of their radiologic evaluation. CT images from all cases were evaluated to determine tumor morphology, presence and localization of calcification, extent of bladder invasion and metastases. Tumor size at presentation averaged 6 cm. Twenty-one of 25 (84%) were mixed cystic solid lesions and 4/25 (16%) were completely solid. Calcifications were present in 18/25 (72%), with 11 peripherally located, 3 central only and 4 both. Bladder wall invasion was present in 23/25 (92%), but was seen as an intraluminal mass in only 13/25 (52%). The bulk of the mass was extravesicular in 22/25 (88%). Metastases were present in 12/25 (48%). Our series supports observations from other smaller series that a midline, calcified, supravesicular mass is highly suspicious, if not pathognomonic, for urachal carcinoma.

From the archives of the AFIP: radiologic staging of ovarian carcinoma with pathologic correlation.

Ovarian cancer is the deadliest gynecologic malignancy, with approximately 70% of patients having peritoneal involvement at the time of diagnosis. It spreads predominantly by direct invasion and intraperitoneal dissemination. The staging system is surgically based, with stage I disease being limited to one or both ovaries. In stage II disease, there is extraovarian spread of tumor, but it does not extend beyond the pelvis. Stages III and IV disease are considered advanced, with stage III ovarian cancer including diffuse peritoneal disease involving the upper abdomen and stage IV disease having distant metastases including hepatic lesions. Common sites of intraperitoneal seeding include the omentum, paracolic gutters, liver capsule, and diaphragm. Thickening, nodularity, and enhancement are all signs of peritoneal involvement. Although computed tomography is the most common imaging modality used to stage ovarian cancer, magnetic resonance imaging has been shown to be equally accurate. Currently, however, no imaging modality allows microscopic spread of disease to be ruled out, and a full staging laparotomy is always required. Early ovarian cancer is treated with comprehensive staging laparotomy, whereas advanced but operable disease is treated with primary cytoreductive surgery (debulking) followed by adjuvant chemotherapy. Patients with unresectable disease may benefit from neoadjuvant (preoperative) chemotherapy before debulking.

From the archives of the AFIP: extratesticular scrotal masses: radiologic-pathologic correlation.

The extratesticular scrotal contents consist of the epididymis, spermatic cord, and fascia derived from the embryologic descent of the testis through the abdominal wall. As opposed to intratesticular masses, most extratesticular masses are benign. Cystic masses (including hydroceles, epididymal cysts, and varicoceles) are easily diagnosed with ultrasonography (US) and are benign. Epididymitis is a common extratesticular lesion as well as the most frequent cause of an acute scrotum. It may be either acute or chronic and can be potentially complicated by epididymo-orchitis or scrotal abscess. Findings include epididymal enlargement, skin thickening, hydroceles, and hyperemia. The epididymis can also be affected by sarcoidosis, a noninfectious granulomatous disorder. The most common extratesticular neoplasms are lipomas (most often arising from the spermatic cord) and adenomatoid tumors (most often found in the epididymis). Despite their relative rarity, malignant neoplasms do occur and include rhabdomyosarcoma, liposarcoma, leiomyosarcoma, malignant fibrous histiocytoma, mesothelioma, and lymphoma. These tumors are often large at the time of presentation. The US findings of solid masses are often nonspecific. Magnetic resonance imaging can be very helpful in the evaluation of some of these disorders, allowing for a more specific diagnosis in cases of lipoma, fibrous pseudotumor, and polyorchidism.

From the archives of the AFIP: tumors and tumorlike lesions of the testis: radiologic-pathologic correlation.

Testicular carcinoma represents only 1% of all neoplasms in men, but it is the most common malignancy in the 15-34-year-old age group. Germ cell tumors constitute 95% of all testicular tumors. Germ cell tumors are a varied group of neoplasms whose imaging features reflect their underlying histologic characteristics. Seminomas are generally well-defined homogeneous lesions, whereas the nonseminomatous tumors (embryonal carcinoma, yolk sac tumor, choriocarcinoma, teratoma, and mixed germ cell tumor) have a much more varied appearance. Germ cell tumors follow a predictable pattern of spread via the lymphatic drainage to the retroperitoneal nodes. Choriocarcinoma, which has a proclivity for early hematogenous spread, is a notable exception. Testicular tumors may also arise from the sex cords (Sertoli cells) and stroma (Leydig cells). Although 90% of these tumors are benign, there are no reliable imaging criteria to differentiate them from malignant masses. Some benign testicular masses can be recognized, obviating an unwarranted orchiectomy. A dilated rete testis is a normal variant and appears as a series of small tubules near the mediastinum testis. Other benign lesions that can be suspected on the basis of imaging findings and history include intratesticular cysts, epidermoid cysts, congenital adrenal hyperplasia, and sarcoidosis.