QUIZ: No. 30, 11/10/2025

X ray

CT

MRI

ANS – Plexiform neurofibroma arising along the superficial peroneal nerve in the distal leg with thick calcifying subperiosteal haemorrhage showing peripheral calcification in NF1.

Findings – Well-defined, hypodense lesion with thick peripheral calcification in subperiosteal plane adjacent to distal fibula without cortex erosion.

Fusiform T1 hypointense, T2 hyperintense lesion, showing mild patchy enhancement, without necrosis or marrow invasion.

MRI brain – FASI; Spine – posterior vertebral scalloping in lumbar spine → consistent with NF1.

In Neurofibromatosis Type 1 (NF1):

1.     Plexiform neurofibromas arise from multiple nerve fascicles, often involving long segments of peripheral nerves (in this case superficial peroneal nerve).

2.     NF1 is associated with mesodermal dysplasia and vascular fragility — the small vessels within the lesion and adjacent periosteum are abnormal and fragile.

3.     Even minor trauma or spontaneous bleeding may lead to subperiosteal hemorrhage.

4.     Over time, this hemorrhage organizes and calcifies, producing a thick peripheral rim of dystrophic calcification.

P.S – Biopsy confirmed as plexiform neurofibroma