A Rare Case of Malignant Granular Cell Tumor of the Colon Incidentally Detected by 18 F-FDG Positron Emission Tomography/Computed Tomography

Abrikossoff tumor, also called granular cell tumor (GCT), is a neoplasm of the soft tissues which is most commonly a solitary, painless, and benign tumor. However, 2% of Abrikossoff tumors can be malignant. We report here the case of a 75-year-old male who presented a local recurrence of Abrikossoff tumor of the left thigh. The anatomopathological analysis concluded to a malignant GCT, and the F-18 fluorodeoxyglucose positron emission tomography showed multiple lesions in the lymph nodes and bones. The potential conversion to malignancy should alert practitioners because of the extremely poor prognosis. The diagnosis of malignant granular cell tumor should be based on a bundle of clinical and histological features and not solely on histologic features because of the challenging distinction between malignant and benign tumors due to the lack of well-defined criteria for the diagnosis of malignancy. Large size and recurrence are the most important clinical features predicting malignant behavior. Patients with a history of Abrikossoff tumor should be followed closely to monitor recurrence and malignant transformation. The apparent originality of our observation – which could lie in the evolution of a GCT tumor, initially considered as benign, to a malignant form – has to be challenged regarding the issue of classifying some cases according to the classical “benign” and “malignant” dichotomy.

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Performance characteristics of 18F-fluciclovine positron emission tomography/computed tomography prior to retroperitoneal lymph node dissection

Canadian Urological Association Journal ◽

10.5489/cuaj.7317 ◽

2021 ◽

Vol 16 (3) ◽

Author(s):

Solomon L. Woldu ◽

Xiaosong Meng ◽

Daniel Wong ◽

Fady Baky ◽

Vitaly Margulis ◽

...

Keyword(s):

Computed Tomography ◽

Positron Emission Tomography ◽

Cell Tumor ◽

Emission Tomography ◽

Retroperitoneal Lymph Node Dissection ◽

Node Dissection ◽

Retroperitoneal Lymph Node ◽

Positron Emission ◽

Pet Ct ◽

18F Fdg

Introduction: We aimed to determine whether anti-1-amino-3-18F-fluorocyclobutane-1-carboxylic acid (18F-fluciclovine) positron emission tomography/computed tomography (PET/CT) can accurately detect residual non-seminomatous germ cell tumor (NSGCT) prior to retroperitoneal lymph node dissection (RPLND). There is no reliable way to differentiate between fibrosis/necrosis, teratoma, and viable germ cell tumor in patients receiving post-chemotherapy RPLND. Functional imaging, including 18F-fludeoxyglucose (18F-FDG) PET/CT, has been disappointing. Due to the need for better imaging modalities, our prospective, pilot study aims to investigate the accuracy of 18F-fluciclovine PET/CT in detecting residual tumor prior to RPLND. Methods: From March 2018 to May 2019, 10 eligible patients underwent preoperative 18F-fluciclovine PET/CT prior to undergoing bilateral, full-template RPLND or excision of mass (for one re-do RPLND) in a prospective, phase 2 study. Correlation between 18F-fluciclovine PET/CT and RPLND pathology were evaluated on a per-patient level. Results: A total of 10 patients (mean age 29±7.6 years) underwent 18F-fluciclovine PET/CT prior to surgery. Nine of 10 patients received chemotherapy prior to RPLND. Correlation between 18F-fluciclovine PET/CT and RPLND pathology was seen in 3/10 (30%) patients. Five of 10 patients (50%) with negative 18F-fluciclovine PET/CT were found to have residual disease/teratoma on RPLND. Compared to the reference standard of RPLND, 18F-fluciclovine PET/CT demonstrated 29% sensitivity and 33% specificity. No patients experienced any adverse events due to 18F-fluciclovine PET/CT. Conclusions: Despite a different mechanism of action from 18F-FDG, 18F-fluciclovine has low sensitivity and specificity for residual teratoma in the retroperitoneum.

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