Incidentally Detected Oropharyngeal Squamous Cell Carcinoma on 18F-Fluciclovine PET/CT

Risk of malignancy in incidental oropharyngeal lesions exhibiting fluorodeoxyglucose uptake which proceed to tissue biopsy

BACKGROUND

Utilization of positron emission tomography/computed tomography (PET/CT) with fluorodeoxyglucose is increasing in use for a variety of indications, including surveillance of cancer patients. There is a paucity of evidence pertaining to the significance of incidental PET-avid oropharyngeal lesions. This study aims to examine the clinical and radiological features of these incidental oropharyngeal lesions in patients undergoing PET for indications other than head and neck cancer.

METHODS

Retrospective cohort study of three Australian tertiary hospitals, from 2015 to 2021, on adult patients undergoing biopsy of incidental PET-avid oropharyngeal lesions. Primary outcome of interest was the incidence of malignancy. Patients with a previous history of, or undergoing investigations for, head and neck cancer were excluded.

RESULTS

Thirty-one patients were included, wherein 21 patients had tonsillar uptake, and 13 patients had base of tongue uptake. Tonsillar disease was mostly asymmetrical (n = 15/21), bilateral (n = 11/21), and had median SUVmax 9.35 (n = 12, IQR 7.4-11.15). Base of tongue was mostly asymmetrical (n = 7/13, 54%), bilateral (n = 8/13, 62%), and had median SUVmax 8.2 (n = 10, IQR 6.9-12.65). Seven patients had malignancy confirmed on tissue biopsy: five biopsies confirmed the tissue diagnosis of suspected lymphoma, and two incidental findings of unexpected malignancies: one p16 positive tonsillar squamous cell carcinoma, and one metastatic breast cancer.

CONCLUSION

In 31 patients undergoing tissue biopsy for incidental PET-avid oropharyngeal lesions, there were two unexpected malignancies. Our study results indicate that although unexpected malignancies are uncommon, a malignant diagnosis cannot be excluded from clinical features alone.

18F-FDG and 18F-Fluciclovine Uptake in Poorly Differentiated Lung Adenocarcinoma in the Setting of Biochemically Recurrent Prostatic Adenocarcinoma

ABSTRACT

A 64-year-old man with a history of Gleason 7 (3 + 4) pT2cN0 prostatic adenocarcinoma status post prostatectomy underwent a fluciclovine PET/CT that showed a tracer-avid right upper lobe spiculated solitary pulmonary nodule. Follow-up FDG PET/CT showed a hypermetabolic right upper lobe spiculated solitary pulmonary nodule. Fine-needle aspiration was consistent with primary lung adenocarcinoma. Subsequently, right upper lobectomy was performed, and poorly differentiated lung adenocarcinoma was confirmed.

18F-Fluciclovine-Avid Reactive Axillary Lymph Nodes After COVID-19 Vaccination

ABSTRACT

A 74-year-old man presenting with biochemical recurrent prostate cancer 9 months after robotic-assisted radical prostatectomy and pelvic lymphadenectomy underwent 18F-fluciclovine PET/CT for restaging to determine subsequent treatment strategy. Serum prostate-specific antigen was 0.7 ng/mL at the time of imaging. Images demonstrated foci of abnormal increased 18F-fluciclovine uptake corresponding to prominent round lymph nodes in the left axilla, some of which with fatty hila. Due to recent mRNA COVID-19 vaccination in the ipsilateral arm and the low likelihood of nodal metastases to the axilla from prostate cancer in this patient, the lymph nodes were considered to be benign, reactive to the vaccine.

PET/CT variants and pitfalls in prostate cancer: What you might see on PET and should never forget

2-deoxy-2-[¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET) gained an impressive role in the diagnostic management of many oncological diseases, even though its use in imaging prostate cancer (PC) is limited to selected cases, mostly advanced stage of PC and selection for prostate specific antigen membrane (PSMA) radioligand therapy (RLT). In the past years, several PET tracers have been developed for both staging and restaging PC. The three most employed PET molecules in daily practice are [¹¹C] or [¹⁸F]F-Choline, [¹⁸F]F-Fluciclovine (Anti-1- amino-3-[18F]Fluorocyclobutane-1-Carboxylic Acid, also known as (Anti-[¹⁸F]FACBC), [⁶⁸Ga]Ga-PSMA and recently FDA approved the first Fluorinated PSMA-based named [¹⁸F]F-DCFPyl. Each one has its own physiological and peculiarity which are worth exploring. Moreover, an increasing number of case reports and studies have reported tracers' variants, pitfalls, or even non-prostatic diseases (benign and malignant) incidentally detected. In prostate oncology, PET can be performed with several indications in different stages of disease, as highlighted in the EAU Guidelines on PC. A correct scan interpretation depends on the knowledge of both the physiological distribution of the tracers and the uptake of possible variants and pitfalls. The aim of this critical review is to provide a comprehensive knowledge of physiological distribution of these three tracers, as well as an updated overview of variants and pitfalls.

Giant pleomorphic sarcoma of the tongue base - a cured clinical case report and literature review

Pleomorphic sarcoma of the tongue base is an extremely rare pathology finding. Our review of current databases returned fewer than 10 articles available free full text on this subject. We review the current state of art management guidelines for this type of tumor. Our case presented surprisingly a favorable evolution despite the huge dimensions, the tumor type, and associated pathology. The patient received radiation therapy and oncological treatment followed by revision surgery consisting of partial glossectomy for the residual tumor. Histological examination of the operatory specimen showed a residual tumor of pleomorphic sarcoma type, with clear margins. The evolution was without relapse after 18 months.

Incidental 18F-Fluciclovine Uptake in a Desmoid Tumor Detected in a Patient Undergoing PET/CT Imaging for Prostate Cancer

ABSTRACT

A 74-year-old man with biochemical recurrent prostate cancer underwent 18F-fluciclovine PET/CT for restaging to determine subsequent treatment strategy. 18F-fluciclovine PET/CT imaging demonstrated incidental focal heterogeneous increased 18F-fluciclovine uptake corresponding to a soft tissue nodule within the musculature of the left anterior abdominal wall. Subsequent ultrasound-guided biopsy of the lesion revealed histopathology compatible with a desmoid tumor. Consequently, the patient underwent surgical resection with wide local excision of the lesion.

Gastrointestinal Stromal Tumor Incidentally Detected on 18F-Fluciclovine PET/CT

ABSTRACT

We present a case of metastatic gastrointestinal stromal tumor incidentally detected on 18F-fluciclovine PET/CT. A 68-year-old man with history of intermediate-risk prostate cancer (Gleason score 4 + 3 = 7; pT2cN0M0) previously treated with retropubic radical prostatectomy, adjuvant whole pelvis radiation, and androgen deprivation therapy (leuprolide) presented with slowly rising serum prostate-specific antigen over 3 years, concerning for recurrent prostate cancer. To identify potential sites of recurrent disease, an 18F-fluciclovine PET/CT was obtained. Multiple tracer-avid mesenteric masses and enlarged lymph nodes were found throughout the abdomen and pelvis, later biopsy-proven to reflect metastatic gastrointestinal stromal tumor.

Incidental Detection of Urothelial Carcinoma on 18F-Fluciclovine PET/CT

ABSTRACT

18F-Fluciclovine PET/CT has become a common diagnostic imaging study used in the evaluation of biochemical recurrence in prostate cancer since its approval in 2016. We present a case report of an 82-year-old man with history of both prostate and bladder cancer who presented for a fluciclovine study due to rising PSA levels. There was incidental detection of focal penile activity, and a subsequent urethral biopsy performed showed urothelial carcinoma, which was also seen on a subsequent MRI study.

18F-Fluciclovine Uptake in a Ureterocele

A 60-year-old man with prostate adenocarcinoma status post radical prostatectomy and bilateral pelvic lymph node dissection referred for restaging F-fluciclovine PET/CT due to rising serum prostate-specific antigen levels (1.1 ng/mL at that time of imaging). PET/CT images were obtained from the proximal thighs to the vertex of the skull approximately 3 to 5 minutes after the IV administration of 347.8 MBq (9.4 mCi) of F-fluciclovine. PET/CT imaging demonstrated a focus of abnormally increased F-fluciclovine uptake at the right ureterovesical junction. Subsequent MRI of the pelvis revealed that this focus corresponded to a benign ureterocele.

PET/CT in Surgical Planning for Head and Neck Cancer

Fluorine-18 (¹⁸F)-fluorodeoxyglucose (FDG) positron emission tomography fused with computed tomography (PET/CT) is a valuable tool in surgical planning for head and neck squamous cell carcinoma (HNSCC). If performed prior to biopsy or other surgical intervention, FDG-PET/CT has high sensitivity for the detection of the primary site in patients with cervical lymph node metastases from unknown primary origin and can be used to direct the surgical workup. FDG-PET/CT is superior to CT alone for detection of nodal metastases outside the expected pattern or distant metastases or second primary cancers and can greatly affect determination of appropriate management including surgical eligibility. Prior to the advent of PET/CT, many patients undergoing (chemo)radiation-based therapy had planned post-treatment neck dissection; FDG-PET/CT now has a proven role in the evaluation of recurrent or persistent disease amenable to salvage surgery and enables safe avoidance of planned postradiation neck dissection with a high negative predictive value. Specifically for this important application, two standardized reporting metrics may be used in the head and neck anatomic region: the "Hopkins criteria" and the "Neck Imaging Reporting and Data System"; both systems produce a formalized evaluation and recommendation based on PET/CT findings. The role of PET/CT as a replacement for elective neck dissection or examination under anesthesia remains controversial but deserves further study. FDG-PET/CT has a wide-ranging impact on the surgical management of patients with HNSCC and should be used routinely in patients with unknown primary nodal disease and those presenting with advanced-stage cancers at initial staging and to assess treatment response.

Synchronous Malignancies Identified by 18F-fluciclovine Positron Emission Tomography for Prostate Cancer: Case Series and Mini-Review

Positron emission tomography using the fluorine-18 (¹⁸F) fluciclovine radiotracer has been approved for use in recurrent prostate cancer and is a useful tool for clinical decision making. However, ¹⁸F-fluciclovine is not specific for prostate cancer tumor cells, and false-positive results have been reported. In the present study, we have reported our experience with synchronous malignancies identified using ¹⁸F-fluciclovine and reviewed other reported cases, with a special emphasis on highlighting the clinical decisions that led to the correct diagnosis.

Extraprostatic Uptake of 18F-Fluciclovine: Differentiation of Nonprostatic Neoplasms From Metastatic Prostate Cancer

OBJECTIVE. Fluciclovine is a synthetic radiolabeled amino acid analog used for imaging of biochemical recurrent prostate cancer. Uptake of fluciclovine is mediated by several amino acid transporters, including alanine-serine-cysteine transporter 2 and large neutral amino acid transporters, which are known to be overexpressed in other malignancies. CONCLUSION. Knowledge of the common patterns of prostate cancer recurrence, in addition to what other neoplasms can show uptake, is critical for accurate study interpretation.