Inguinal Endometriosis Visualized on I-131 Whole Body Scan

Radioiodine whole body scan pitfalls in differentiated thyroid cancer

PURPOSE

whole body scan (WBS) performed following diagnostic or therapeutic administration of I-131 is useful in patients with differentiated thyroid carcinoma. However, it can be falsely positive in various circumstances. We aimed to report a series of pitfalls in a clinical perspective.

METHODS

A search in the database PubMed utilizing the following terms: "false radioiodine uptake" and "false positive iodine 131 scan" has been made in January 2023. Among the 346 studies screened, 230 were included in this review, with a total of 370 cases collected. Physiological uptakes were excluded. For each patient, sex, age, dose of I-131 administered, region and specific organ of uptake and cause of false uptake were evaluated.

RESULTS

370 cases of false radioiodine uptake were reported, 19.1% in the head-neck region, 34.2% in the chest, 14.8% in the abdomen, 20.8% in the pelvis, and 11.1% in the soft tissues and skeletal system. The origin of false radioiodine uptake was referred to non-tumoral diseases in 205/370 cases (55.1%), benign tumors in 108/370 cases (29.5%), malignant tumors in 25/370 cases (6.7%), and other causes in 32/370 cases (8.7%).

CONCLUSIONS

WBS is useful in the follow-up of patients with differentiated thyroid carcinoma, however it can be falsely positive in various circumstances. For this reason, it is critically important to correlate the scintigraphic result with patient's medical history, serum thyroglobulin levels, additional imaging studies and cytologic and/or histologic result.

Inguinal endometriosis: Ten case reports and review of literature

BACKGROUND

To describe the characteristics, diagnosis and surgical treatment of inguinal endometriosis (IEM).

CASE SUMMARY

We retrospectively analyzed 10 patients diagnosed with IEM at Beijing Chao-Yang Hospital from 2011 to 2019. Relevant features, symptoms, images, surgical treatment, hormonal therapy and follow-up were collected and discussed. A total of 10 cases of IEM diagnosed by surgery and pathology were characterized by a lesion on the right side (9/11); five patients had symptoms related to the menstrual cycle, and only 3 patients were clearly diagnosed before surgery. Ultrasonography was of little assistance in confirming the diagnosis, but magnetic resonance imaging showed specific, high-intensity patterns. Anatomically, most of the IEM lesions were located in the extraperitoneal ligament (10/11); nine patients had inguinal hernias (IH), five had concurrent or prior pelvic endometriosis, and four had infertility. The clinical results from extensive resection were satisfactory.

CONCLUSION

IEM is an extremely rare condition that can easily be misdiagnosed prior to surgery. A right IH may contribute to the formation of right-sided IEM, and extensive resection involving the round ligament and hernia sac is essential to prevent recurrence.

Endometriosis of the Inguinal Canal Mimicking a Hydrocele of the Canal of Nuck

Isolated presentation of endometriosis of the inguinal canal is infrequent, and the clinical and imaging findings may be misleading in such patients. We describe an otherwise healthy female with isolated inguinal endometriosis presenting as a hydrocele of the canal of Nuck. Surgeons should consider such unusual presentations and obtain imaging and histological evaluations in doubtful instances. Complete excision was curative in our patient with no evidence of recurrence.

Unexpected False-positive I-131 Uptake in Patients with Differentiated Thyroid Carcinoma

Objective:

Radioiodine is the most specific radionuclide for differentiated thyroid carcinoma (DTC) imaging. Despite its high specificity and sensitivity, false-positive I-131 uptake could be seen on whole body scan (WBS) that may lead to misdiagnosis and unnecessary radioiodine treatment. In this study, we aimed to present the I-131 WBS and concomitant single photon emission computed tomography/computed tomography (SPECT/CT) images of unexpected false-positive radioiodine uptake along with the patients’ clinical outcomes and the contribution of SPECT/CT imaging.

Methods:

I-131 WBSs of 1507 patients with DTC were retrospectively reviewed, and anticipated I-131 uptakes (like in breasts or thymus) were excluded from the study. The unexpected false-positive I-131 uptakes with concomitant SPECT/CT imaging were included in the study.

Results:

Twenty-one patients had 23 unexpected I-131 uptakes on WBS and concomitant SPECT/CT imaging. The vast majority (87%) of these cases were seen on post-therapeutic I-131 WBS. Most of the false-positive I-131 uptakes could be explained by SPECT/CT and radiologic findings, and were secondary to non-thyroid conditions (bronchiectasis, lung infection, subcutaneous injection into gluteal fatty tissue, aortic calcification, benign bone cyst, vertebral hemangioma, recent non-thyroid surgical procedure site, rotator cuff injury, mature cystic teratoma and ovarian follicle cyst). However, the possible reasons of 9 false-positive I-131 uptakes could not be explained by radiologic findings.

Conclusion:

We suggest that false-positive I-131 uptake and its underlying mechanisms (inflammation, trapping, increased perfusion, etc.) must be kept in mind in patients with thyroid cancer and unexpected findings must be considered together with serum thyroglobulin levels, SPECT/CT and radiologic findings in order to avoid misdiagnosis and unnecessary radioiodine treatment.