Unusual Case of an Exophytic Leiomyoma of Rectum Mimicking Malignancy on 18F-FDG PET/CT

Uncommon Detection of Leiomyoma in the Penile Corpus Spongiosum Using FDG PET/CT: A Case Report

ABSTRACT

Primary tumors of the penile corpus spongiosum are rare. Hereby we describe the scintigraphic findings of a case of penile leiomyoma within the corpus spongiosum tissue, which was incidentally detected on FDG PET/CT. The benign neoplasm was growing in close proximity to the urethra showing increased focal FDG uptake on sequential PET/CT studies. Subsequently, the patient experienced obstructive urinary symptoms, and the tumor was resected. We concluded that the possibility of neoplasm should be kept in mind while evaluating a patient with persistent focal penile FDG uptake, which may be the first and only manifestation of the disease.

Comparison of 18 F-FDG and 68 Ga-FAPI PET/CT in a Rare Renal Leiomyoma

ABSTRACT

Renal leiomyoma is a rare benign mesenchymal tumor of the kidney, which mainly originates from the renal capsule or pelvis. We described 18 F-FDG and 68 Ga-FAPI PET/CT findings in a case of renal leiomyoma. The PET/CT findings showed that the left renal leiomyoma demonstrated intensively increased 68 Ga-FAPI uptake, whereas only inhomogeneously slightly increased 18 F-FDG uptake. This case illustrates that 68 Ga-FAPI PET/CT may be an effective tool for detecting renal leiomyoma.

Anorectal leiomyoma with GLUT1 overexpression mimicking malignancy on FDG-PET/CT

A 43-year-old female underwent pelvic magnetic resonance imaging for uterine myoma that incidentally revealed a 4.6 × 2.8 cm soft tissue mass in the anorectal region. Rectal endoscopy showed a submucosal tumor just above the anal canal. Fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) revealed an anorectal tumor with very high FDG uptake. Aspiration cytology and needle biopsy were inconclusive, and the patient underwent trans-perineal tumor resection. The excised tumor was a 4.6 × 3.5 × 2.7 cm gray-white bifurcated nodular tumor. Light microscopy revealed fenestrated growth of poorly dysmorphic short spindle-shaped cells with eosinophilic sporophytes. Immunohistochemical staining was positive for αSMA and desmin, negative for CD117 (KIT) and S100, and the patient was diagnosed with benign leiomyoma. Tumor cells were also positive for glucose transporter-1 (GLUT1) immunohistochemically. It is important to keep in mind that FDG-PET/CT may show false-positive results even in benign anal leiomyoma for various reasons, including GLUT1 overexpression.