First Acute Case of Ossifying Subperiosteal Hematoma After Plexiform Neurofibroma Resection in NF-1: Case Report and Systematic Review.

Background: Plexiform neurofibromas (PNs) are observed in approximately 30-50% of patients with neurofibromatosis type 1 (NF-1) and can occasionally present with rare complications such as subperiosteal hemorrhage (OSH). Methods: We report the first documented case of an acute, massive ossifying subperiosteal hematoma requiring drainage following PN excision. A systematic review of the literature identified six similar pediatric cases with gradual-onset OSH. Results: A 17-year-old male with NF-1 underwent surgical resection of a large neurofibromatous mass in the left ankle. Postoperatively, he developed sudden pain, swelling, and fever due to a rapidly expanding hematoma, which required surgical drainage. Histology revealed PN with ossification and hemorrhagic elements. Most similar cases, included in this review, required surgery due to symptom severity. Conclusion: Our findings suggest that adolescent NF-1 patients with large PNs in the lower limbs are at risk for acute OSH and require close monitoring, particularly during the perioperative period. This case underscores the importance of early recognition and tailored intervention for this rare but potentially severe complication.