Rationale:Interdigitating dendritic cell sarcoma (IDCS) is an extremely rare disease. It commonly occurs in middle-aged males and mainly involves the lymph nodes. Pathological examination plays an important role in differentiating from other tumors, but far less published literature focuses on the imaging characteristics of IDCS.Patient concerns:Here, we reported a case of IDCS in a 52-year-old male involving the pelvis with medical imaging and pathologic findings.Diagnoses:Preoperative unenhanced CT scan revealed a 6.0 × 6.3 × 8.0 cm mass with density equal to that of adjacent muscle, located in the pelvis. On contrast-enhanced CT images, the tumor presented apparent homogeneous enhancement. CT angiography showed that the tumor was supplied by the branches of inferior mesenteric artery. Pelvic magnetic resonance imaging manifested a lobulated solid mass with low signal on T1-weighted and intermediate to high signal on T2-weighted images. Simultaneously, significantly high signal intensity was exhibited on the diffusion-weighted images. This patient underwent operative resection of the tumor. The pathologic diagnosis was IDCS.Interventions:This patient underwent operative resection of the tumor. The resection margins were negative for the neoplastic proliferation and no distant metastases were found. The patient did not receive advanced radiotherapy or chemotherapy.Outcomes:Three months after surgery, the follow-up CT scan did not reveal any recurrence or metastases.Lessons:This case adds to the experience with IDCS by summarizing its characteristics as well as reviewing the literature.

The aim of the study was to investigate dynamic contrast enhanced MRI (DCE-MRI) as a potential marker to assess the therapeutic responses of fecal microbiota transplantation (FMT) in patients with Crohn's disease (CD) and to determine the parameter or combination of parameters most strongly associated with changes in clinical indicators after treatment.In 22 CD patients, DCE-MRI was performed with a 3.0T scanner. Parameters of DCE-MRI (vascular transfer constant [Ktrnas] and blood volume [BV]) in the terminal ileum were compared between before and day 90 after FMT treatment. The differences of clinical indicators (C-reactive protein [CRP], Harvey–Bradshaw index [HBI]) and DCE-MRI parameters (Ktrnas, BV) between pre- and post-treatment was calculated by Student's 2-tailed, paired t-test. The correlations between percent change of clinical indicators (ΔCRP, ΔHBI) with DCE-MRI parameters (ΔKtrnas, ΔBV) were analyzed by Pearson's correlation coefficients. A logistic regression model was used to identify the changes of DCE-MRI parameters related to the treatment outcomes. Receiver operating characteristic curves (ROCs) were generated to assess which DCE-MRI parameter showed the best accuracy for evaluation of therapeutic response.After treatment, mean values of clinical indicators decreased significantly (CRP: 62.68 ± 31.86 vs 43.55 ± 29.63 mg/L, P = .008; HBI: 7.18 ± 2.10 vs 5.73 ± 2.33, P = 0.012). Both DCE-MRI parameters showed prominent differences before and after treatment: Ktrans (1.86 ± 0.87 vs 1.39 ± 0.83 min−1, P = .017), BV (61.02 ± 28.49 vs 41.96 ± 22.75 mL/100 g, P = .005). There were significant correlations between ΔCRP or ΔHBI and percent change of CDE-MRI parameters (ΔKtrans to ΔCRP: 0.659; ΔKtrans to ΔHBI: 0.496; ΔBV to ΔCRP: 0.442; ΔBV to ΔHBI: 0.476). Compared to ΔKtrans and ΔBV individually, the combination of both parameters performed best in assessment of therapeutic response with an area under the ROCs (AUC) of 0.948.Ktrans and BV parameters derived from DCE-MRI have the potential to assess for therapeutic response after FMT treatment for CD. The combination of Ktrans and BV measurements improved the predictive capability compared to the individual parameters.