There is a paucity of existing literature centering on the magnetic resonance (MR) imaging features of pancreatic schwannomas, due to the neoplasm's nonspecific presentation and its rarity. We aimed to identify the characteristic imaging features of pancreatic schwannoma.

This retrospective search was conducted for histologically confirmed pancreatic schwannoma in multi-institutional database of pathology. Abdominal magnetic resonance imaging (MRI) was performed before histologic examination and their MR imaging studies were independently reviewed. The search yielded six adults (mean age, 46 years) with a definitive histologic postoperative diagnosis of single pancreatic schwannoma each. Additionally, a comprehensive English and Chinese literature review for pancreatic schwannoma and reported MR-imaging findings since 1961 was also conducted. MR imaging features of those cases in the literature were analyzed, summarized and compared with our case series.

This rare entity appeared to be a well-circumscribed, exophytic, oval or round pancreatic mass with a mean greatest diameter of 3.7 cm. Five schwannomas were located in the pancreatic head-neck and one in the pancreatic tail. On MRI, all cases appeared hypointense on T1-weighted images, inhomogeneous hyperintense on T2-weighted images, and hyperintense on diffusion-weighted images. The mean apparent diffusion coefficient (ADC) values of pancreatic schwannoma were 1.11 ± 0.29 × 10- 3 mm2/s and significantly lower than the surrounding pancreas. The lesion-to-pancreas signal intensity ratio (SIR) at unenhanced T1-weighted images was 0.53 ± 0.07. On dynamic contrast-enhanced MRI, most of the lesions (67%, 4/6) showed homogeneously iso- or hypointense on arterial and portal venous phases, and hyperenhancement on delayed phase compared with the surrounding pancreas. In our analysis of the time intensity curves, all cases exhibited a gradual enhancement pattern.

A well-circumscribed mass displaying inhomogeneous hyperintensity on T2, marked hypointensity on T1, hyperintensity on DWI, and with early slight enhancement at arterial phase and progressive enhancement at portal venous and delayed phase, may suggest the diagnosis of pancreatic schwannoma.

This is a clinical case of a 48-year-old patient with chronic abdominal pain in association with a mesenteric tumor of neurogenic strain. Intra-abdominal schwannomas are an infrequent entity, characterized by presenting a larval and paucisymptomatic clinic and may even be a casual finding. Malignant degeneration is uncommon. Surgical excision is the gold standard to achieve definitive healing.

Schwannomas (or neurilemmomas) are slow-growing mesenchymal neoplasms of the peripheral nerve sheath that may arise at almost any anatomical site. Mesentery schwannoma is extremely rare, with less than ten previously described cases. We present the case of a 38-year-old woman with arterial hypertension and chronic kidney disease with an abdominal painless mass of two years duration and an inconclusive pre-operative clinical diagnosis; she was successfully treated by complete surgical resection of the mass. The aim of this report is to recognize the possibility of schwannomas in the differential diagnosis of abdominal slowly growing tumors.

Neurilemmoma, also known as schwannoma, is an uncommon benign neoplasm that is most commonly found in the trunk and head and neck regions. The present study reports the case of a 67-year-old female with schwannoma localized in the anterior abdominal wall and analyzes the ultrasound and computed tomography (CT) imaging observations of the schwannoma. A dynamic time-intensity curve was also recorded in the study. A well-defined, elliptic low echo level, heterogeneous mass was observed during ultrasound examination. The CT scan revealed a solid, heterogeneous, low-density mass in the abdominal wall. Contrast-enhanced scans showed a heterogeneously enhanced mass during the arterial and venous phase. Centripetal fill-in was demonstrated and the mass was markedly, homogenously enhanced relative to the muscles during the delayed phase. Peak enhancement was observed during the venous phase and then slowly declined. However, the mass was hyperattenuated during the delayed phase. The lesion was completely excised and no evidence of recurrence has been identified during the 3 months of follow-up. The present study suggested that a diagnosis of schwannoma should be considered for certain patients with masses in the abdominal wall. Peripheral enhancement during the arterial and venous phases and homogeneous enhancement in the delayed phase are the significant imaging findings of a schwannoma.