Rare Mesenchymal Tumors of the Pelvis: Imaging and Pathologic Correlation

Unveiling the swirl sign: A radiologic-pathologic correlation in deep angiomyxoma

Deep angiomyxoma (DA) is a rare, slow-growing soft tissue tumor typically affecting women of reproductive age. Despite its benign histology, it poses significant clinical challenges due to local invasiveness and high recurrence. Accurate diagnosis through radiologic imaging, particularly MRI, is essential for guiding treatment. One key imaging feature of DA is the "swirl sign," a distinctive pattern on T2-weighted images. However, its histological basis remains unclear. Here, we present a case of DA in a 46-year-old woman, highlighting the correlation between radiologic and histopathologic findings. MRI showed the characteristic swirl sign, which histologically corresponded to straight-running blood vessels aligned with the tumor's long axis, supported by collagen fibers within an edematous stroma. This case offers novel insight into the origins of the swirl sign and provides research questions on this sign. Further research is needed to explore its potential as a biomarker for tumor growth and aggressiveness.

Multimodality Imaging Features of Papillary Renal Cell Carcinoma

Objectives: To describe the US, CEUS, CT, and MRI features of papillary renal cell carcinoma (PRCC) and to underline the imaging characteristics that are helpful in the differential diagnosis. Methods: Patients with histologically proven papillary renal cell carcinoma who underwent at least two imaging examinations (US, CEUS, CT, and MRI) were included in the study. Tumor size, homogeneity, morphology, perilesional stranding, contrast enhancement locoregional extension were assessed. A comparison and the characteristics of the imaging features for each imaging modality were analyzed. Results: A total of 27 patients with an histologically confirmed diagnosis of PRCC were included in the study. US was highly accurate in distinguishing solid masses from cystic masses, supporting the differential diagnosis of PRCC, as well as in patients with a poor representation of the solid component. CEUS significantly increased diagnostic accuracy in delineating the solid intralesional component. Furthermore, when using CEUS, in the arterial phase, PRCC exhibited hypo-enhancement, and in the late phase it showed an inhomogeneous and delayed wash-out compared with the surrounding renal parenchyma. At MRI, PRCC showed a marked restiction of DWI and was hypointense in the T2-weighted compared to the renal parenchyma. Conclusions: In our study, the characteristic hypodensity and hypoenhancement of PRCC make CT the weakest method of their recognition, while US/CEUS and MRI are necessary to reach a definitive diagnosis. Knowledge of the appearance of PRCC can support an early diagnosis and prompt management, and radiologists should be aware that PRCC, when detected using CT, may resemble spurious non-septate renal cyst.

Cellular Angiofibroma of the Perineal Region With Tortuous Vessels: A Report of Three Cases

Cellular angiofibroma (CA) is a slow-growing, painless benign soft tissue tumor that commonly arises in the superficial soft tissue of the vulvovaginal or inguinoscrotal regions. Since CA shares many pathological and imaging similarities with angiomyofibroblastoma and aggressive angiomyxoma, its preoperative imaging diagnosis can be challenging. To the best of our knowledge, this is the first report describing tortuous vessels around the tumor as imaging findings to assist in diagnosing CA and distinguishing it from angiomyofibroblastoma and aggressive angiomyxoma in the perineal region.

Imaging the Female Urethra: US and MRI in Cystic and Solid Pathologic Conditions

The female urethra can be affected by numerous pathologic conditions, many of which are infrequent and often underdiagnosed, particularly before the introduction of MRI. Diagnosing urethral pathologic conditions is challenging due to ambiguous signs and symptoms, nonspecific physical examinations, atypical presentations (such as benign conditions mimicking malignant disorders), and large lesions. Various imaging techniques, including transperineal or transvaginal US and MRI, are essential for accurate anatomic and tissue characterization. Female urethral pathologic conditions can be categorized into cystic lesions (with urethral diverticulum as the most common), benign and malignant solid urethral lesions, and iatrogenic lesions. Defining the location of the pathologic finding is the first step in radiologic diagnosis. By analyzing tissue characteristics (cystic versus noncystic), shape, morphology, and location (including urethral dependence and relationship to the pubic symphysis), an accurate diagnosis can often be achieved. Identifying whether a lesion is urethral-dependent helps distinguish between urethral and other conditions, such as Bartholin gland and Gartner duct cysts. Radiologists must recognize these features to determine the most appropriate diagnostic and therapeutic strategies. ©RSNA, 2025 Supplemental material is available for this article.

Intraperitoneal pelvic leiomyoma with atypical location in an old man: The role for MRI in the differential diagnosis

Primary pelvic peritoneal masses, not arising from major organs, are uncommon in adults. Leiomyomas are a group of benign smooth muscle tumors, most commonly found in the uterus in premenopausal women (70-80%). Extra-uterine locations are very rare and more frequent in women. We highlighted the role of MRI due to its capability in soft tissue characterization, that may positively impact the therapeutical decision-making process. Herein, we present the case of a 66-year-old man with a peritoneal solid mass suspicious for a leiomyoma at Magnetic Resonance Imaging and confirmed at histologic specimen in order to discuss the crucial imaging findings that could raise suspicion of such a rare pathology in man.

Cystic Angiomyofibroblastoma of the Uterus Mimicking Ovarian Cancer

Angiomyofibroblastoma (AMFB) is an exceedingly rare mesenchymal tumor of the lower genital tract. AMFB primarily affects the pelviperineal region, especially the vulvar in premenopausal women. Typically, AMFB is a benign disease and does not have the potential for metastasis or recurrence, requiring complete surgical excision. Its accurate differentiation from aggressive angiomyxoma is critical due to varying prognoses. A 51-year-old woman, diagnosed with mucinous carcinoma of the breast, presented with a 12 cm abdominopelvic mass identified during breast cancer staging. Imaging suggested an ovarian origin; however, surgical exploration revealed a stalk-attached cystic mass in the anterior body of the uterus. Histopathology confirmed AMFB. Immunohistochemical analysis showed positivity for estrogen and progesterone receptors and smooth muscle actin. The patient continued breast cancer treatment postoperatively without pelvic mass recurrence or complications for a postoperative follow-up period of one year. This case highlights AMFB's potential uterine body origin, expending known tumor sites and complicating diagnosis due to overlapping features with other mesenchymal tumors. Accurate diagnosis using immunohistochemical markers and pathological features is essential to avoid unnecessary aggressive treatments. The uterine location in this case suggests a possible shared pathogenesis with uterine myomas, warranting further research into their connection. Reporting the first case of AMFB originating in the uterine body enhances understanding of this rare condition and underscores the importance of clinical awareness and precise diagnostic strategies to guide management and improve outcomes.

Radiology-Pathology Correlation of Peri-Anal Aggressive Angiomyxoma and Cellular Angiofibroma: Two Case Reports

Aggressive angiomyxoma and cellular angiofibroma are uncommon mesenchymal tumors. Imaging plays an important role in suggesting their diagnosis and in delineating the extent of the lesion. Additionally, histopathological examination provides the definite diagnosis. An understanding of their histological features and correlating that with the key imaging features on radiology helps in narrowing the differential diagnosis, and thereby aids in management and outcome. We herein present a case of both entities in patients presenting with history of a palpable peri-anal mass. We describe the radiological and histological features of aggressive angiomyxoma and cellular angiofibroma and highlight the similarities and differentiating factors between them.

Extracranial Meningioma-Pelvic Bone on FDG PET/CT: A Rare of the Rarest Site

ABSTRACT

Meningiomas are benign extra-axial tumors of the central nervous system. Extracranial meningiomas are extremely rare (2%) and can develop as a direct extension from a primary intracranial meningioma or as a true primary extracranial meningioma originating from ectopic arachnoid cells. We report an extremely unusual case of a 61-year-old woman who was diagnosed with pelvic meningioma with the help of PET/CT and PET/CT-guided biopsy. The clinicopathological features of the patient and immunoprofile of the tumor are presented.

Misleading clinical and imaging features in atypical aggressive angiomyxoma of the female vulvovaginal or perianal region: report of three cases and review of the literature

Objectives

Aggressive (deep) angiomyxoma (AAM) is a rare mesenchymal tumor that typically originates from the vulvovaginal region, perineum, and pelvis in adult women. The objective of this case report and literature review is to comprehensively analyze the clinical, imaging, and pathological characteristics of atypical AAM in the female lower genital tract and pelvic floor in order to minimize preoperative misdiagnosis or missed diagnosis and ultimately optimize the clinical management strategy.

Methods

The data of three cases with atypical AAM, which demonstrate similarities with other lesions observed in the female lower genital tract over the past 1.5 years, were retrospectively described. This description included clinical management, images and reports of ultrasonography (US) and magnetic resonance imaging (MRI), clinicopathological features, follow-up, and outcomes. In the Discussion section, a review of the literature on MEDLINE (PubMed) and Web of Science from the past 50 years was conducted.

Results

The three cases all underwent preoperative ultrasonography, and two of them also underwent preoperative MRI examination. Complete resection of the lesions was performed in all three cases, followed by postoperative pathological examination. The histopathology of these three cases revealed invasive angiomyxoma, as confirmed by immunohistochemical staining, which demonstrated positive expression of desmin, vimentin, estrogen, and progesterone receptors. The patients experienced a smooth postoperative recovery. Ultrasound had a diagnostic accuracy rate of 100% (3/3) for locating and determining the extent of the lesions; however, its specific diagnostic accuracy rate for identifying the pathological type was only 33% (1/3). In contrast, MRI had a diagnostic accuracy rate of 100% (2/2) for locating and determining the extent of lesions but did not show any specific diagnostic accuracy for identifying the pathological types.

Conclusions

Our findings indicate that even if a vulvovaginal lesion presents with a superficial location, small size, limited scope, and regular shape, suspicion of atypical AAM should arise when palpation reveals toughness, tensility, and deformability under pressure. US reveals a well-defined hypoechoic to anechoic mass with uniformly distributed coarse dot echoes, with or without detectable intratumoral blood flow signal. MRI shows prolonged T1 and T2 signals with inhomogeneous enhancement and evident diffusion restriction on diffusion-weighted imaging (DWI).

Imaging of Castleman Disease

Castleman disease (CD) is a group of rare and complex lymphoproliferative disorders that can manifest in two general forms: unicentric CD (UCD) and multicentric CD (MCD). These two forms differ in clinical manifestation, imaging appearances, treatment options, and prognosis. UCD typically manifests as a solitary enlarging mass that is discovered incidentally or after development of compression-type symptoms. MCD usually manifests acutely with systemic symptoms including fever and weight loss. As a whole, CD involves lymph nodes throughout the chest, neck, abdomen, pelvis, and axilla and can have a wide variety of imaging appearances. Most commonly, lymph nodes or masses in UCD occur in the chest, classically with well-defined borders, hyperenhancement, and possible characteristic patterns of calcification and/or feeding vessels. Lymph nodes affected by MCD, while also hyperenhancing, tend to involve multiple nodal chains and manifest alongside anasarca or hepatosplenomegaly. The polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes (POEMS) subtype of MCD may demonstrate lytic or sclerotic osseous lesions in addition to features typical of MCD. Since a diagnosis of CD based solely on imaging findings is often not possible, pathologic confirmation with core needle biopsy and/or surgical excision is necessary. Nevertheless, imaging plays a crucial role in supporting the diagnosis of CD, guiding appropriate regions for biopsy, and excluding other potential causes or mimics of disease. CT is frequently the initial imaging technique used in evaluating potential CD. MRI and PET play important roles in thoroughly evaluating the disease and determining its extent, especially the MCD form. Complete surgical excision is typically curative for UCD. MCD usually requires systemic therapy. ^©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Multimodality Imaging Assessment of Desmoid Tumors: The Great Mime in the Era of Multidisciplinary Teams

Desmoid tumors (DTs), also known as desmoid fibromatosis or aggressive fibromatosis, are rare, locally invasive, non-metastatic soft tissue tumors. Although histological results represent the gold standard diagnosis, imaging represents the fundamental tool for the diagnosis of these tumors. Although histological analysis represents the gold standard for diagnosis, imaging represents the fundamental tool for the diagnosis of these tumors. DTs represent a challenge for the radiologist, being able to mimic different pathological conditions. A proper diagnosis is required to establish an adequate therapeutic approach. Multimodality imaging, including ultrasound (US), computed tomography (CT) and Magnetic Resonance Imaging (MRI), should be preferred. Different imaging techniques can also guide minimally invasive treatments and monitor their effectiveness. The purpose of this review is to describe the state-of-the-art multidisciplinary imaging of DTs; and its role in patient management.