Contrast-enhanced ultrasound (CEUS) was successfully used to percutaneously biopsy a multirecurrent rectal gastrointestinal stromal tumor (GIST), according to a case study published in Radiology Case Reports.

The patient had a local recurrence of the rectal GIST in the presacral and precoccygeal space after multiple resections and treatment with imatinib mesylate. CEUS-guided biopsy was used to obtain a sample of the lesion to avoid the necrotic portion at the center of the mass and achieve higher accuracy for histological sampling.

Subsequent pathological examination confirmed the tumor as GIST and found positivity for CD117, DOG1, and CD34, along with negativity for SMA and desmin. Molecular examination revealed negative results for PD-L1 and PDGFRA but a positive mutation of exon 11 in c-kit.


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“Magnetic resonance and computed tomography are the main imaging techniques for diagnosis and follow-up, while ultrasound and contrast-enhanced ultrasound may be useful to perform a percutaneous biopsy, as in the case presented,” the authors said.

The patient was initially diagnosed with rectal GIST in 2000 after a perineal mass was found during a routine gynecological checkup. Biopsy of the mass confirmed GIST, and the tumor was removed using a laparoscopic anterior rectal resection.

A local recurrence was found in 2001, and the patient was started on immunotherapy with imatinib, which led to progressive volume reduction of the mass. Excision surgery to remove the tumor in 2003 was complicated by a recto-vaginal fistula. The fistula was surgically removed in 2005.

Regular follow-up showed no recurrence until 2008, when there was a new recurrence, and the patient was started on another round of imatinib. MRI was performed in 2020, and it revealed a richly vascularized solid mass in the precoccygeal region with expansion into the fat tissue of the ischio-rectal fossae.

Imatinib was initiated once again, but imaging 6 months later revealed that the tumor had grown from a previous mean diameter of 3.9 cm to 4.5 cm. CEUS-guided biopsy was then initiated to differentiate the presence of a different mesenchymal tumor and also evaluate the potential to start a new targeted biological therapy since imatinib proved unsuccessful.

Reference

Andresciani F, Vertulli D, Pacella G, et al. CT, MR, and CEUS imaging features of recurrent GIST of the pre-sacral space: a case report. Radiol Case Rep. Published online October 31, 2022. doi:10.1016/j.radcr.2022.09.098