Bladder Hernia Simulating Left Inguinal Metastasis on PET/CT

Case History: A 49-year-old man with a history of right pyriform sinus carcinoma was assessed every 6 months for evaluation of tumor recurrence.

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Figure 1. PET scan image showing intese uptake in left inguinal region. Uptake in mediastinal lymphnodes also seen.

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Figure 2 a. Axial fused FDG-PETCT image showing intense FDG uptake in left inguinal region due to herniated urinary bladder.

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Figure 2 b.

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Figure 2 c.

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Figure 3a. Coronal fused FDG-PETCT image Intense FDG uptake in left inguina region due to herniated urinary bladder.

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Figure 3b.

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Figure 3c.

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Figure 4 a. CT image showing herniation of anterior wall of bladder in to left inguinal region.

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Figure 4b.

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Figure 5. Fused PET-CT image showing FDG avid metabolically active nodule in middle lobe of right lung.

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Figure 6. Axial Fused PET CT image showing FDG avid lymphnode in right.

Diagnosis: Inguinal hernia of a portion of the bladder wall simulated a nodal metastasis.

Discussion: Whole body images (skull to midthigh) were acquired in 3D mode 60 minutes after IV injection of 370 MBq of 18 F-FDG using a dedicated Philips Gemini GXL 16 PET/CT scanner. Oral and IV contrast were administered. Reconstruction of the acquired data was performed so as to obtain fused. PET/CT images in transaxial, coronal and sagittal views. Standard uptake values (SUV) normalized to body surface area obtained over lesions. For the PET/CT, patients fasted at least six hours before the intravenous injection of 18F-FDG, with scanning beginning 60 minutes afterwards.

In our patient, PET showed intense FDG uptake seen in left inguinal canal region (Figure 1). Serial axial (Figure 2a-b) and coronal (Figure 3a-c) FDG PET showed an unexpected and intense FDG uptake in left inguinal region, which was considered to be inguinal nodal metastasis.

Subsequently, the PET/CT images were retrospectively reviewed together with the relevant CT anatomic data (Figure 4a-b). The lesion with intense FDG uptake was interpretated as a herniation of the left anterior wall of the bladder into the left inguinal canal rather than metastasis.

¹⁸FDG uptake by semiquantitative analysis using the maximum standardized uptake value (SUVmax) for each focus of urinary bladder, hernia SUVmax was 33.8 for urinary bladder, and 28.6 for hernial segment. The high SUVmax in the bladder and hernia was explained by accumulated intense radiotracer activity by urinary excretion of FDG.

It was later confirmed the patient had suffered for 8 years from a herniation in the left inguinal area that often extended to the scrotal region when he walked for long periods. The herniated segments were easily reduced by manual assistance and by changing positions from standing to supine. The patient was asymptomatic and had no difficulty in micturition even during the herniated status.

Fused images also show FDG avid metabolically active lung nodule in right lung in middle lobe (Figure 5) and enlarged FDG avid metabolically active mediastinal lymphnodes (Figure 6).

Our case report demonstrates the possibility of misinterpreting PET images without combining relevant CT data. In conclusion, this report describes a case in which an inguinal hernia of a portion of the bladder wall simulated a nodal metastasis.

Harpreet Singh, MD, JP Scan Private Diagnostic Center, Khanna, Punjab, India