Nasofrontal heterotopic ossification following lymphangioma resection

Heterotopic ossification (HO) is the formation of mature lamellar bone in soft tissues. Heterotopic ossification can occur locally following surgical trauma, most commonly after total hip arthroplasty. Periosteal stripping, organizing hematoma, and extensive soft tissue dissection have been associated with subsequent HO. Craniomaxillofacial HO is rare and almost always associated with injury to the muscles of mastication. We present a report of biopsy-established HO of the cranium. An 18-month-old boy presented with a soft, compressible mass in the forehead midline, which did not extend intracranially on computed tomography scan. Surgical exploration revealed a poorly marginated lymphangioma infiltrating the periosteum of the nasofrontal region. This was debulked to restore nasofrontal contour. Two months postoperatively, after minor accidental trauma, the patient developed a subperiosteal hematoma that was evacuated in the clinic. Eight months postoperatively, the patient returned with a visible nasofrontal prominence overlying a firm immobile mass. Computed tomography scan revealed a 3-cm horn-like osseous structure extending inferiorly from the frontal bone across the nasofrontal junction. The bony mass was resected via a coronal approach and confirmed as HO with hematopoietically active marrow.