Suture Granuloma With False-Positive Findings on FDG-PET/CT Resected via Laparoscopic Surgery

PET-positive suture granuloma of abdominal wall 56 years post-appendicectomy mimicking recurrence of lymphoma

We present a unique case of a positron emission tomography (PET)-positive suture granuloma deep to an appendicectomy abdominal wall scar from 56 years prior in a patient with treated lymphoma. The lesion was first detected 8 years ago on a PET scan for new diagnosis of follicular lymphoma, with stable appearances 6 and 7 years later at follow-up. Ultrasound-guided biopsy and flow cytometry of the specimen could not exclude an untreated or recurrent lymphoma; thus, the patient underwent resection of the right iliac fossa abdominal wall lesion. Histopathology results noted granulomatous inflammation surrounding foreign material. The patient had an uneventful postoperative recovery and was discharged from surgical services. In this paper, we review the current literature and discuss the dilemma involved in the diagnosis and management of suture granulomas.

Evaluation of a CD13 and Integrin αvβ3 Dual-Receptor Targeted Tracer 68Ga-NGR-RGD for Ovarian Tumor Imaging: Comparison With 18F-FDG

Ovarian cancer has the highest mortality rate of gynecologic malignancy. ¹⁸F-FDG positron emission tomography (PET) adds an important superiority over traditional anatomic imaging modalities in oncological imaging but has drawbacks including false negative results at the early stage of ovarian cancer, and false positives when inflammatory comorbidities are present. Aminopeptidase N (APN, also known as CD13) and integrin α_vβ₃ are two important targets overexpressed on tumor neo-vessels and frequently on ovarian cancerous cells. In this study, we used subcutaneous and metastatic models of ovarian cancer and muscular inflammation models to identify ⁶⁸Ga-NGR-RGD, a heterodimeric tracer consisting of NGR and RGD peptides targeting CD13 and integrin α_vβ₃, respectively, and compared it with ¹⁸F-FDG. We found that ⁶⁸Ga-NGR-RGD showed greater contrast in SKOV3 and ES-2 tumors than ¹⁸F-FDG. Low accumulation of ⁶⁸Ga-NGR-RGD but avid uptake of ¹⁸F-FDG were observed in inflammatory muscle. In abdominal metastasis models, PET imaging with ⁶⁸Ga-NGR-RGD allowed for rapid and clear delineation of both peritoneal and liver metastases (3-6 mm), whereas, ¹⁸F-FDG could not distinguish the metastasis lesions due to the relatively low metabolic activity in tumors and the interference of intestinal physiological ¹⁸F-FDG uptake. Due to the high tumor-targeting efficacy, low inflammatory uptake, and higher tumor-to-background ratios compared to that of ¹⁸F-FDG, ⁶⁸Ga-NGR-RGD presents a promising imaging agent for diagnosis, staging, and follow-up of ovarian tumors.

Suture granuloma extending intra-abdominally, detected five months postappendectomy

Objective:

Suture granulomas are localised inflammatory reactions that develop at the site of retained suture material. They are a rare surgical complication that is sometimes radiologically challenging to diagnose, especially if the intra-abdominal is communicating with the anterior abdominal wall.

Methods:

The case reported here was a 22-year-old female who presented with right iliac fossa pain 5 months post-appendectomy, which turned out to be due to a suture granuloma. Ultrasonography and CT with and without contrast misdiagnosed the lesion as an abscess or less likely as neoplasm. Conclusive diagnosis was based upon histopathological examination of tissue obtained by biopsy.

Conclusion:

When reviewing the images of patients who present with post-operative surgical complications, it is crucial to consider suture granuloma as a distinct possibility. A definitive diagnosis saves the patient from undergoing unnecessary extensive surgeries and improves the patient experience.

Palpable Lumps after Mastectomy: Radiologic-Pathologic Review of Benign and Malignant Masses

Patients who have undergone mastectomy, with or without reconstruction, are not universally screened with mammography or US. Therefore, clinical breast examination by the physician and patient-detected palpable abnormalities are crucial for detecting breast cancer or recurrence. Diagnostic US is the first-line modality for evaluation of postmastectomy palpable masses, with occasional adjunct use of diagnostic mammography for confirming certain benign masses. In the setting of a negative initial imaging evaluation with continued clinical concern, diagnostic MRI may aid in improving sensitivity. Knowledge of the typical multimodality imaging appearances and locations of malignant palpable abnormalities-such as invasive carcinoma recurrence, cancer in residual breast tissue, radiation-induced sarcoma, and metastatic disease-is crucial in diagnosis and treatment of these entities. In addition, familiarity with the range of benign palpable postmastectomy processes-including fat necrosis, fat graft, seroma, granuloma, neuroma, fibrosis, and infection-may help avoid unnecessary biopsies and reassure patients. The authors review common and rare benign and malignant palpable masses in mastectomy patients, describe multimodality diagnostic imaging evaluation of each entity, review radiologic and pathologic correlation, and acquaint the radiologist with management when these findings are encountered. ^©RSNA, 2021.

Differentiation between suture recurrence and suture granuloma after pulmonary resection for lung cancer by diffusion-weighted magnetic resonance imaging or FDG-PET / CT

There has been no publication which supports the usefulness of DWI differentiating for suture recurrence and suture granuloma after resection for lung cancer. We presented efficacy of DWI or FDG-PET/CT for an assessment of suture lesions after resection for lung cancer. Thirteen suture recurrences and 15 suture granulomas were examined. There were 24 adenocarcinomas and 4 squamous cell carcinomas, and 26 partial resections and 2 segmentectomies. The period of time (907±907 days) between surgery and suture recurrence was not significantly longer than that (546±547 days) between surgery and suture granuloma. Diffusion detectability scores (a 5-point scale) of suture recurrences was significantly higher than that of suture granulomas. The ADC value (1.35±0.24 × 10^-3mm²/sec) of suture recurrences was significantly lower than that (1.85±0.60 × 10^-3mm²/sec) of suture granulomas. The SUVmax (6.1 ± 5.0) of suture recurrences was not significantly higher than that (4.2 ± 2.5) of suture granulmas. The sensitivity of 85% (11/13) with DWI was not significantly higher than 69% (9/13) with FDG-PET/CT for suture recurrences. The specificity of 73% (11/15) with DWI was not significantly higher than the 60% (9/15) with FDG-PET/CT for suture granulomas. The accuracy of 79% (22/28) with DWI was not significantly higher than that of 64% (18/28) with FDG-PET/CT for suture recurrences and granulomas. DWI can differentiate suture granuloma from suture recurrence after resection of lung cancer. DWI is more useful than FDG-PET/CT for the differentiation between suture recurrence and suture granuloma after resection for lung cancer.

Large Idiopathic Mesenteric Necrotizing Granuloma Mimicking Metastatic Disease on FDG PET/CT

On restaging FDG PET/CT for an 81-year-old man with oral cavity cancer, a large FDG-avid mesenteric mass suspicious for either metastasis or second primary was incidentally noted. Surgical pathology showed necrotizing granulomatous inflammation without evidence of tumor. All stains were negative for microorganisms. An elastin stain was negative as well, which excluded an origin of damaged blood vessels or vasculitis. The patient had no prior abdominal surgery or known gastrointestinal disease. Granuloma always poses a dilemma in the interpretation of PET/CT, due to its high FDG avidity and mass-like appearance which mimics neoplastic disease.

A case of Schloffer tumor with rapid growth and FDG-PET positivity at the port site of laparoscopic sigmoidectomy for colon cancer

Background

Schloffer tumor is a foreign body granuloma in the abdominal subcutaneous layer that develops due to a foreign body such as suture from several months to years postoperatively. Herein, we report a case of a rapidly growing Schloffer tumor with F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) positivity at the port site of laparoscopic sigmoidectomy for colon cancer.

Case presentation

An 85-year-old man, who underwent laparoscopic sigmoidectomy for stage IIIa sigmoid colon cancer 10 months ago, was referred to our hospital with complaints of a growing mass in the abdominal wall. The tumor was palpable at the right-sided abdominal wall corresponding to the port site of laparoscopic sigmoidectomy. The tumor rapidly grew for 2 months. Computed tomography showed a ring-enhanced mass at the right-sided abdominal wall. PET examination revealed high accumulation of FDG in the tumor. Tumor resection was performed due to suspected port site recurrence. The pathological diagnosis was inflammatory granuloma, so-called Schloffer tumor.

Conclusion

In the era of laparoscopic surgery, Schloffer tumor may be one of the differential diagnoses for rapidly growing tumor with FDG-PET positivity at the port site in postoperative patients with advanced colorectal cancer.

The value of using fludeoxyglucose positron-emission tomography scan with respect to colorectal abnormalities-a cross-sectional study

Background

Fludeoxyglucose positron-emission tomography (FDG-PET) shows colic uptake regularly. Complementary colonoscopy is done. Aim: study the findings of colonoscopy.

Methods

All consecutive scans in 5 years were studied. Focal FDG uptake in colon and/or rectum were scored as + or ++. Clinical files and endoscopy reports were studied for final diagnosis.

Results

Focal FDG uptake was noted in 173 out of 2,075 scans (8.4%). Focal FDG activity was judged ++ in 73 patients (42.2%) and + in 100 (57.8%). The majority of colorectal cancers scored ++. Patients with ++ activity underwent or had undergone significantly more often a colonoscopy compared with patients with + activity, 82% versus 65% (P=0.02). FDG PET/CT was false positive with respect to polyp(s) or cancer in 13 cases (22%) of ++ FGD activity and in 38 cases of + FDG (P<0.001). In 25 patients a total of 69 polyps were not FDG avid.

Conclusions

FDG-PET scanning is a useful tool in oncology. However, false-positive and false-negative findings with respect to colonic uptake are present in a significant number of patients. If the clinical condition and the potential prognosis allows the performance of colonoscopy this procedure should be done.

Diagnostic value of integrated ¹⁸F-fluoro-2-deoxyglucose positron emission tomography/computed tomography in recurrent epithelial ovarian cancer: accuracy of patient selection for secondary cytoreduction in 134 patients

Objective

The aim of this study was to evaluate the diagnostic value of integrated ¹⁸F-fluoro-2-deoxyglucose-positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) for suspected recurrence of epithelial ovarian cancer (EOC) with non-disseminated lesions.

Methods

We retrospectively reviewed the medical records of recurrent EOC patients who underwent secondary cytoreduction from January 2000 to December 2013. A total of 134 patients underwent secondary cytoreduction after imaging with either ¹⁸F-FDG-PET/CT or contrast-enhanced computed tomography (CECT).

Results

In a patient-based analysis of 134 patients, 124 (92.5%) were confirmed to be positive for malignancy. Among 72 patients with suspected non-disseminated recurrence on ¹⁸F-FDG-PET/CT, 65 (89.0%) were confirmed to have recurrence, giving 98.5% sensitivity, 87.7% accuracy, and 88.9% positive predictive value (PPV). In the 65 patients with recurrence, residual tumor remained in 14 patients, giving an accuracy of patient selection for secondary cytoreduction of 69.4% (50/72) and it is higher than that of CECT (64.0%). In 169 lesions removed from patients who underwent preoperative ¹⁸F-FDG-PET/CT, 135 (79.9%) were confirmed to be positive for malignancy and 124 were accurately detected by ¹⁸F-FDG-PET/CT, giving 91.9% sensitivity, 81.1% accuracy, and 85.5% PPV. Foreign body granuloma was found in 33.3% of 21 lesions with false-positive ¹⁸F-FDG-PET/CT findings (7/21). The mean preoperative cancer antigen 125 (CA-125) level in false-positive patients was 28.8 U/mL.

Conclusion

Compared with CECT, ¹⁸F-FDG-PET/CT shows higher sensitivity in lesion-based analysis and better accuracy of patient selection for secondary cytoreduction. However, there is still a need for integration of the results of ¹⁸F-FDG-PET/CT, CECT, and CA-125 levels to aid treatment planning.

Silk suture granuloma with false-positive findings on PET/CT accompanied by peritoneal metastasis after colon cancer surgery

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Suture granuloma is relatively rare.

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After tumor resection, positive PET/CT findings could indicate suture granuloma.

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Postoperative PET/CT surveillance might give false-positive findings.

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PET/CT cannot detect small peritoneal metastatic lesions.

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A surgical examination should be performed when metastases are suspected.

Introduction

Suture granuloma is a rare benign tumor caused by suture material, which usually appears several months or years after surgery.

Presentation of case

A 71-year-old man underwent sigmoidectomy and partial hepatectomy (S6) for sigmoid colon cancer and synchronous liver metastasis at a previous hospital. At 4 postoperative months, surveillance computed tomography (CT) revealed a suspicious tumor at the hepatic resection stump. He was referred to our hospital for further examinations and treatments. Positron emission tomography/CT (PET/CT) revealed abnormal hepatic F-18 fluorodeoxyglucose (FDG) uptake below the diaphragm at the S5/S8 surface. Peritoneal metastasis was suspected and surgery was performed. White nodules were found in the Douglas pouch. A diagnosis of adenocarcinoma was confirmed by frozen section analysis of the nodules. He underwent a partial hepatectomy (S5/S8) and partial resection of the diaphragm. Pathological examination showed that the liver tumor was a foreign body granuloma that included silk suture material.

Discussion

Although postoperative PET/CT surveillance is useful following malignant tumor resection, it is important to note that PET/CT false-positive findings are possible. Furthermore, PET/CT cannot detect small peritoneal metastases, necessitating a thorough abdominal examination.

Conclusion

In cases of malignancy, the possibility of postoperative suture granuloma should be considered. In addition, a thorough surgical examination of the abdomen should be performed in cases of suspected recurrence.

18F-FBPA as a tumor-specific probe of L-type amino acid transporter 1 (LAT1): a comparison study with 18F-FDG and 11C-Methionine PET

PURPOSE

The purpose of this study was to evaluate the usefulness of L-4-borono-2-¹⁸F-fluoro-phenylalanine (¹⁸F-FBPA) as a tumor-specific probe, in comparison to ¹⁸F-FDG and ¹¹C-methionine (Met), focusing on its transport selectivity by L-type amino acid transporter 1 (LAT1), which is highly upregulated in cancers.

METHODS

Cellular analyses of FBPA were performed to evaluate the transportablity and K_m value. PET studies were performed in rat xenograft models of C6 glioma (n = 12) and in rat models of turpentine oil-induced subcutaneous inflammation (n = 9). The kinetic parameters and uptake values on static PET images were compared using the one-tissue compartment model (K₁, k₂) and maximum standardized uptake value (SUVmax).

RESULTS

The cellular analyses showed that FBPA had a lower affinity to a normal cell-type transporter LAT2 and induced less efflux through LAT2 among FBPA, Met, and BPA, while the efflux through LAT1 induced by FBPA was similar among the three compounds. The K_m value of ¹⁸F-FBPA for LAT1 (196.8 ± 11.4 μM) was dramatically lower than that for LAT2 (2813.8 ± 574.5 μM), suggesting the higher selectivity of ¹⁸F-FBPA for LAT1. K₁ and k₂ values were significantly smaller in ¹⁸F-FBPA PET (K₁ = 0.04 ± 0.01 ml/ccm/min and k₂ = 0.07 ± 0.01 /min) as compared to ¹¹C-Met PET (0.22 ± 0.09 and 0.52 ± 0.10, respectively) in inflammatory lesions. Static PET analysis based on the SUVmax showed significantly higher accumulation of ¹⁸F-FDG in the tumor and inflammatory lesions (7.2 ± 2.1 and 4.6 ± 0.63, respectively) as compared to both ¹⁸F-FBPA (3.2 ± 0.40 and 1.9 ± 0.19) and ¹¹C-Met (3.4 ± 0.43 and 1.6 ± 0.11). No significant difference was observed between ¹⁸F-FBPA and ¹¹C-Met in the static PET images.

CONCLUSION

This study shows the utility of ¹⁸F-FBPA as a tumor-specific probe of LAT1 with low accumulation in the inflammatory lesions.