Schwannoma, typically a non-cancerous tumor originating from Schwann cells, seldom occurs in the retroperitoneal area. Its clinical manifestation varies, often remaining asymptomatic for an extended period until it enlarges, exerting pressure on neighboring organs. This article presents a unique instance of retroperitoneal pelvic schwannoma in a 75-year-old woman, initially presenting with unusual lower back discomfort. Imaging was used to characterize the tumor, and anatomopathological examination established the preoperative diagnosis of pelvic schwannoma and its benign nature. The clinical, imaging, and anatomopathological aspects of this pelvic schwannoma case are elucidated herein.

Retroperitoneal chyloma is a rare entity that presents with non-specific symptoms. Although benign, it can cause complications due to the mass effect. In this case report, we present the case of a 24-year-old woman who presented with a complaint of left-sided colicky abdominal pain and mild dysuria for one year. On physical examination, there was only mild abdominal tenderness. Computed tomography (CT) revealed a thick-walled cystic retroperitoneal mass with a small amount of fat in the superior part and a displaced left hydronephrotic kidney. Magnetic resonance imaging (MRI) confirmed the findings and also revealed a fat-fluid level in the cyst. A laparotomy was performed, and the cystic mass, containing milky fluid, was excised. Histopathology showed a pseudocyst with chronic inflammation and a xanthomatous reaction, with no evidence of infection or malignancy. The patient recovered without complications and has not had a recurrence so far. Retroperitoneal chyloma is difficult to diagnose preoperatively. A definitive diagnosis is usually made only after surgery and a histopathological examination. The treatment of choice is a complete excision. Other approaches, such as marsupialization or drainage, will likely result in a recurrence. However, surgery in the retroperitoneal space is associated with a risk of injury to major vessels or organs. In conclusion, retroperitoneal chyloma is a rare entity that is best treated by complete excision. For small lesions, a wait-and-watch approach may be advisable.

Retroperitoneal cavernous hemangioma, a rare vascular tumor, has only 30 PubMed cases. Preoperative diagnostic criteria are unclear and often present asymptomatically until complications such as rupture or compression arise. We present a 73-year-old with chronic abdominal pain and a giant retroperitoneal tumor. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed an irregular space-occupying mass in the retroperitoneum, suggesting a retroperitoneal chronic expanding hematoma. Total surgical resection confirmed the diagnosis as retroperitoneal cavernous hemangioma.

BACKGROUND: Robot-assisted partial nephrectomy (RAPN) can be performed either by a transperitoneal (TP) or a retroperitoneal (RP) approach. However, the superiority of one approach over the other is not established. Hence, the primary aim of this review was to compare perioperative outcomes between these two surgical approaches.
METHODS: Literature was systematically searched to identify studies reporting perioperative outcomes following TP RAPN and RP RAPN. The study protocol was registered with PROSPERO (CRD42023399496). The primary outcome was comparing complication rates between the two approaches.
RESULTS: This review included 22 studies, 5675 patients, 2524 in the RP group, and 3151 in the TP group. The overall complications were significantly lower in the RP group [Odds ratio (OR) 0.80 (0.67, 0.95), p = 0.01]. However, the rate of major complications was similar between the two groups. The operative time was significantly shorter with the RP group [Mean Difference (MD)-16.7 (- 22.3, - 11.0), p =  < 0.0001]. Estimated blood loss (EBL) and need for blood transfusion (BT) were significantly lower in the RP group. There was no difference between the two groups for conversion to radical nephrectomy [OR 0.66 (0.33, 1.33), p = 0.25] or open surgery [OR 0.68 (0.24, 1.92, p = 0.47] and positive surgical margins [OR 0.93 (0.66, 1.31, p = 0.69]. Length of stay (LOS) was shorter in the RP group [MD - 0.27 (- 0.45, - 0.08), p =  < 0.00001].
CONCLUSIONS: RP approach, compared to TP, has significantly lower complication rates, EBL, need for BT and LOS. However, due to the lack of randomized studies on the topic, further data is required.

Ancient schwannomas are a rare variation of schwannomas, with the distinction being based on histopathological examination of the excised specimen. On histopathological examination, ancient schwannomas exhibit degenerative changes such as calcification, hyalinization, and cystic necrosis, along with S100 positivity. Complete surgical excision is the mainstay treatment for ancient schwannomas and carries a favorable prognosis. Recurrence is the most common complication, often arising from incomplete surgical excision. Herein, we present a case of a 41-year-old male who presented to our center as a case of a retroperitoneal mass for further investigations and diagnostic workup. Imaging showed a retroperitoneal mass in the right iliac fossa. We proceeded with ultrasound guided needle biopsy, and examination of the specimen confirmed the diagnosis of ancient schwannoma. Subsequently, the patient underwent surgery, and complete surgical excision was achieved. On follow-up 3-months later, the patient is doing well, and no signs of recurrence were found.

•Key anterior approaches differences in LSTV include vascular (aortic bifurcation/iliocaval confluence), muscular (psoas) and osseus anatomy (inter-crestal tangent/pubic symphysis), when compared to non-LSTV.•There are increased surgical deviations but not significantly greater complications for anterior approaches in LSTV.•Vascular awareness while accessing L45 will be in the presence of a more cephalad ABF and ICC with sacralized L5, and access to the deeper L56 level will be in the presence of a more caudal ABF and ICC in lumbarized S1.

UNASSIGNED: Actinomycosis is an uncommon subacute or chronic suppurative bacterial granulomatous infectious disease with clinical heterogeneity. The majority of actinomycosis cases were of extra-abdominal origin, with oro-cervico-facial cases representing 55%, abdominopelvic representing 20%, and thoracic representing 15% of total reports. Currently, abdominal actinomycosis incidence is approximately 1 case per 119,000 people, being found three times more frequently among males. We report two rare clinical presentations of abdominal actinomycosis affecting the mesentery and the retroperitoneum, respectively.
UNASSIGNED: A 58-year-old Caucasian male presented to our clinic with abdominal pain in the right upper quadrant. Pre-operative evaluation, although inconclusive, showed a mesocolic mass infiltrating the right and transverse colon. The patient underwent exploratory laparotomy. After partial resection of the mass, the histopathology report demonstrated mesenteric actinomycosis.
UNASSIGNED: A 40-year-old Caucasian male presented to our clinic complaining about a mucopurulent material from an orifice at the right inguinal region. After appropriate work-up, a large abdominopelvic, stellate mass (75 x 22.8 mm) in the retroperitoneum was revealed. Surgery along with the appropriate antibiotics was used to treat the patient.
UNASSIGNED: Preoperative suspicion and diagnosis of actinomycosis are very challenging, with a high rate of misdiagnosis often resulting in delayed treatment. Our case reports highlight that abdominal actinomycosis should always be part of differential diagnosis, especially when there is involvement of multiple organs. The gold standard treatment of actinomycosis is surgical excision with prolonged antibiotic treatment.

UNASSIGNED: Anastomotic hemangioma is a rare subtype of capillary hemangioma primarily found in the genitourinary tract. We present a case of a patient with an anastomotic hemangioma located in the retroperitoneal space; then, we explore and summarize the imaging features from previously reported cases for accurate diagnosis.
UNASSIGNED: A 57-year-old woman complained of left lower back pain. Contrast-enhanced ultrasound revealed a hypoechoic mass with \"slow-in and slow-out\" enhancement. Abdominal CT scan displayed a well-defined, round soft tissue mass in the right retroperitoneal region with obvious enhancement. MRI indicated low signal on T1-weighted imaging, high signal on T2-weighted imaging and diffusion-weighted imaging, and progressive enhancement after enhancement. Surgical removal of the tumor was performed. Histopathological examination exhibited a distinct tumor border with interconnected blood vessels and a cavity lined by a single layer of cubic endothelial cells. Immunohistochemistry confirmed the presence of CD31[+] and CD34[+]. The final pathological diagnosis was anastomotic hemangioma. No recurrence was observed during a 40-month follow-up.
UNASSIGNED: Retroperitoneal anastomotic hemangioma is a rare and benign neoplasm that may be misdiagnosed as ectopic pheochromocytoma or angiosarcoma. This case report presents and analyzes the imaging characteristics of a series of retroperitoneal anastomotic hemangiomas, which can be valuable for future diagnoses and help prevent unnecessary surgeries.

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Ganglioneuroma is a rare, benign, well-differentiated neurogenic tumor most commonly located in the posterior mediastinum or retroperitoneum. Giant ganglioneuromas are even less common; this is only the 19th reported case in literature to date. We present a case of a giant retroperitoneal ganglioneuroma in a five-year-old child, which on imaging mimicked a mesenteric cyst and posed various challenges in its management. Histopathology later confirmed our misdiagnosis and revealed the tumor to be a ganglioneuroma. This unique case serves as a lesson for clinicians to not operate before receiving histopathological confirmation of their diagnosis.