Diffuse neurofibromas are ill-defined benign peripheral nerve sheath tumors with infiltrative growth. Although typically isolated, these tumors can occur in patients with neurofibromatosis type 1 (NF1), causing pain, restricted movement, and swelling. This abstract discusses three cases of these concurrent conditions.

Case 1: A 43-year-old female patient with a history of NF1 presented with steady growth of a plaque-like lesion in the left gluteal region. Pelvic MRI showed infiltrative soft tissue mass in subcutaneous space, extending into the superficial fascia of paraspinal musculature. She sought surgical intervention for cosmetic reasons.

Case 2: A 27-year-old male with a history of NF1 presented with increased right leg circumference. A pelvic MRI showed an enhancing lesion involving subcutaneous tissue and gluteus maximus muscle that was surgically resected. Histological findings revealed variable SOX10 expression and CD34-positive dendritic fibroblasts. Due to postoperative growth, Selumetinib, an MEK inhibitor, was recommended.

Case 3: A 32-year-old male with untreated NF1 presented with progressive left hip pain and new-onset numbness in the left leg. An MRI reported lumbar levoscoliosis, lumbar dural ectasia with aneurysmal dilation of right-sided nerve roots, myositis of the right iliopsoas and paraspinal muscles with severe right upper thigh subcutaneous edema, suggested progression of a diffuse neurofibroma.

Diffuse neurofibromas are infiltrative soft tissue tumors occurring in about 10% of patients with neurofibromatosis type 1 (NF1). NF1 mutations are identified in 20-50% of cases, leading to Ras pathway hyperactivation, with the AKT/mTOR and Raf/MEK/ERK pathways as potential therapeutic targets. Diagnosis relies on MRI, histology, and immunochemistry. Currently, effective treatments remain limited; however, selumetinib shows promise in reducing tumor volume and alleviating pain in plexiform neurofibromas, while surgical approaches are controversial. In many cases, supportive therapies may also be required.