Case Report: Appendiceal neurofibroma associated with neurofibromatosis type 1: a rare case and systematic review of the literature.

Abstract

<h4>Background</h4>Appendiceal neurofibroma is exceedingly rare, with fewer than 20 cases reported globally to date. It is most commonly observed in patients with neurofibromatosis type 1 (NF1), and both clinical and imaging characteristics lack specificity.<h4>Case summary</h4>A 31-year-old male presented with a 10-day history of fever; a right-lower-quadrant mass was detected during outpatient evaluation, prompting hospital admission. Abdominal CT revealed a 6.9 × 4.2 cm mass in the appendiceal region, and ultrasound showed the lesion was connected to the appendiceal lumen. The patient underwent appendectomy, partial cystectomy, and partial omentectomy. Histopathological examination revealed spindle cell bundles, with positive S-100 and SOX-10 staining, and Ki-67 expression <2%. The final diagnosis was appendiceal neurofibroma with focal atypical hyperplasia.<h4>Literature search method</h4>A systematic search of PubMed and Embase was conducted to identify previously reported cases of appendiceal neurofibroma.<h4>Results</h4>A total of 16 cases of appendiceal neurofibroma were identified from the English-language literature through PubMed and Embase (excluding the present case). Among the 16 cases reporting gender, 11 were male and 5 were female. The median age of the 16 cases with reported ages was 51 years (range, 19-74 years). Of the 16 cases, 14 were associated with NF1, and 2 were isolated cases of appendiceal neurofibroma. At least 12 cases (75%) presented with right lower quadrant pain or acute appendicitis-like symptoms, while the remaining cases were characterized by abdominal masses, gastrointestinal bleeding, or incidental findings on imaging.<h4>Conclusion</h4>This case of appendiceal neurofibroma presented primarily with persistent fever and lacked typical abdominal pain. Imaging revealed an appendiceal mass closely associated with the bladder. After appendectomy combined with partial cystectomy, the diagnosis of neurofibroma was confirmed by pathology. The patient recovered well postoperatively, and at 6-month telephone follow-up no symptoms suggestive of recurrence were reported; however, no interval imaging was performed.