QUIZ: No. 26, 06/08/2025

CT

ANS – Duodenal Gastrointestinal Stromal Tumor (GIST) in a patient with Neurofibromatosis type 1 (NF1)

Findings – Dumbbell-shaped, well-defined enhancing duodenal mass with exophytic and endophytic component, small necrotic area and air lucency. Associated cutaneous neurofibromas, suggestive of NF1. No significant lymphadenopathy or metastatic deposits.

GISTs occur in 5–25% of patients with NF1, much higher than in the general population.

NF1 patients are predisposed to GISTs, especially in the small bowel (duodenum, jejunum).

GISTs in NF1 cases typically present as well-defined, enhancing masses involving the bowel wall—often with a dumbbell shape (both intra- and extraluminal components).

Larger lesions may show central low attenuation due to necrosis or hemorrhage, and may even demonstrate intratumoral gas if ulcerated into the lumen.

NF1-associated GISTs often lack KIT/PDGFRA mutations, making them less responsive to imatinib and surgical resection remains the primary treatment for localized GISTs.

Take home points

1.     In a patient with NF1 and a duodenal mass, always consider GIST.

2.     Distinguishing from adenocarcinoma is vital since GISTs typically do not show lymphadenopathy and are managed differently.