Abstract
Background
A case of bisphosphonate related osteonecrosis of calvarial bone has not been reported.
Methods
The clinical, imaging, and histopathological findings of the patient are presented. A 72-year-old female treated with bisphosphonates for osteoporosis presented with an open wound of her scalp. CT, MRI and bone scan suggested lytic and sclerotic changes with inflammation.
Results
Surgical debridement was performed and final pathology was consistent with osteonecrosis and osteomyelitis.
Conclusions
This case illustrates that bisphosphonates can induce osteonecrosis of calvarial bone.
1
Introduction
Unfortunately, bisphosphonates have been shown to induce osteonecrosis of the jaw that has been a well-known entity since it was first described in 2003 . The American Society for Bone and Mineral Research defines bisphosphonate-related osteonecrosis of the jaw as an area of exposed bone in the maxillofacial region that has not healed within 8 weeks after identification by a healthcare provider in a patient who is receiving or has been exposed to a bisphosphonate and has not had radiation therapy to the craniofacial region . There have been many case reports of jaw (mandible or maxilla) involvement, few of the external auditory canal and at least one of the skull base though no reported cases of calvarial bone .
2
Case report
A 72-year-old female with a past medical history significant for hypertension, hyperlipidemia, anxiety, GERD, atrial fibrillation, DVT and osteoporosis (had been taking denosumab injections) was initially seen in the office with a complaint of a small lesion over the scalp. She states that the lesion began to develop over the last 4–5 months, which started as a small ulcerative lesion that progressed to exposed bone. She did not have any history of radiation treatments or trauma. Prior to the original office visit, she had been seen by her PCP and another surgeon who obtained a biopsy. The original biopsy was suggestive of inflammatory tissue. The patient had been treated with bactrim as previous cultures grew methicillin sensitive Staphylococcus aureus . On physical exam, the patient had an open wound over the left side near the vertex which measured 4 × 5 cm with exposed skull and no periosteum ( Fig. 1 ). There was an additional lesion over the left side of forehead with ulceration, induration and erythema. CT revealed a large defect involving the left frontal scalp with heterogenous pattern suggestive of inflammation ( Fig. 2 ). MRI revealed enhancement of the scalp, calvarium and epidural space with supratentorial pachymeningeal enhancement ( Fig. 3 ). Bone scan revealed increased radiotracer uptake within a large area of lytic and sclerotic change. In the operating room the PT was found to have an open frontal scalp lesion with purulent drainage, the skull was soft and nonviable ( Fig. 4 ). Frozen sections showed no signs of malignancy, only inflammatory process. The patient subsequently underwent radical scalp resection with craniectomy of frontal-parietal bone and occipital vessel rotational flap reconstruction and split thickness skin graft with placement of wound VAC. Intraoperative cultures revealed rare growth of staph and strep. She was then seen by infectious disease who recommended cefazolin three times per day for 6 weeks. Finally pathologic diagnosis was granulation tissue and inflammation consistent with osteonecrosis and osteomyelitis.
