PMC9927005_01
MRI, US and CEUS findings of the periurethral mass on admission. (A, B) Coronal and sagittal MRI of the pelvis, showing a well-defined mass around the urethra (arrows). (C, D) Transvaginal ultrasonography scan revealed a heterogeneously low echoic mass encasing urethra and color Doppler imaging indicated abundant blood flow signals in the lesion. (E) CEUS image obtained at the 18 sec after contrast injection indicating an overall heterogeneously high enhancement of the mass in the arterial phase. (F) CEUS image obtained at the 27 sec showed quick wash-out of the contrast in the lesion.
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Pelvic gadolinium-enhanced magnetic resonance imaging (MRI) done at the local institution revealed 3.5x3.3x3.7 cm sized periurethral mass which extended from the distal urethra to the bladder neck ( Figures 1A, B ). Then, the patient underwent transvaginal ultrasonography which revealed a large well-defined heterogeneous hypoechoic mass in front of the anterior vaginal wall, measuring 3.7x3.1x3.5 cm ( Figure 1C ). Color Doppler examination demonstrated abundant blood flow signals inside the mass ( Figure 1D ). It turned out that the contrast agent began to wash into the mass in 15 seconds after injection and the mass appeared overall heterogeneously high enhanced and displayed a fast-forward and fast-out pattern ( Figures 1E, F ).
Histopathological examination of the periurethral mass. (A) Hematoxylin and eosin staining (x200) showed fibrous tissue with abundant infiltration of lymphocytes, plasma cells and eosinophils. (B) Immunohistochemical staining (x200) of IgG4-positive plasma cells. (C) Immunohistochemical staining (x400) showed that IgG4-positive plasma cells were above 50 per high power field (arrows). (D) Immunohistochemical staining (x400) revealed the infiltration of IgG-positive cells (arrow heads). IgG4/IgG ratio was 55.6%.
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Figure 2A ). Further immunohistochemistry staining revealed that IgG4-positive plasma cells count was over 50/high power field (HPF) and the IgG4+/IgG ratio was approximately 55.6% ( Figures 2B-D ). In addition, the tissue was stained positive for Ki-67 (30%+), CD34 and CD31 but negative for cytokeratin (CK), anaplastic lymphoma kinase (ALK), smooth muscle actin (SMA), myogenin and myogenic differentiation 1 (MyoD1).
Radiological manifestations of the salivary glands and pancreas and significant improvement of periurethral mass after treatment. (A) An ultrasound image of the right submandibular gland showing numerous patchy hypoechoic regions inside the glandular parenchyma. (B) Contrast-enhanced CT scan of the abdomen showed the pancreas appears diffusely enlarged with a hypodense peripancreatic rim (white arrows). (C) After 3 months of treatment, MRI of the pelvis revealed marked decrease in size of the periurethral mass (white arrows).
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The results of submandibular glands ultrasound showed that the echoes were uneven and there were numerous patchy hypoechoic regions inside the glandular parenchyma ( Figure 3A ). Contrast-enhanced computed tomography (CT) scan of the abdomen showed diffuse enlargement of the pancreas with delayed rim enhancement, which was in accordance to the radiologic manifestations of autoimmune pancreatitis ( Figure 3B ). The serum level of IgG4 was reduced to 608 mg/dL and follow-up pelvic MRI showed the periurethral lesion decreased in size substantially after 3 months of therapy ( Figure 3C ).