Pott puffy tumor

Abstract

Pott puffy tumor is osteomyelitis of the frontal bone with associated subperiosteal abscess causing swelling and edema over the forehead and scalp. It is a complication of frontal sinusitis or trauma. We present the case of an 8-year-old girl with frontal swelling. Imaging evaluation showed frontal osteomyelitis as a complication of frontal sinusitis with associated epidural and subperiosteal abscess. The patient was treated surgically and recovered well. This case highlights the need for high clinical suspicion and early diagnosis and management to prevent life-threatening complications. Unfortunately, in our case the patient had to undergo surgery for this complication, which could have been prevented by earlier diagnosis.

Pott puffy tumor is a rare complication of sinusitis characterized by osteomyelitis of the frontal bone with subperiosteal abscess presenting as frontal swelling. It was first described by Sir Percival Pott in 1768 in relation to frontal head trauma. Later, it was established that this entity is more common in relation to frontal sinusitis (1). We report a case of an 8-year-old girl who presented with gradually increasing frontal swelling.

CASE REPORT

An 8-year-old girl was referred for persistent headaches and gradually increasing frontal swelling for 3 days. She had sinusitis 1 month earlier and was treated with azithromycin. She had multiple drug allergies to penicillin, cephalosporin, and cotrimoxazole. A computed tomography (CT) scan revealed frontal sinusitis with cortical erosions and frontal subperiosteal and epidural soft tissue swelling (Figure 1). Magnetic resonance imaging (MRI) revealed frontal sinusitis, frontal bone defect, and frontal epidural collection with peripheral rim enhancement suggestive of epidural abscess (Figure 2). A small subperiosteal abscess was also noted in the frontal soft tissues. The patient was started on intravenous antibiotics and underwent craniotomy with trephination and drainage of the brain abscess. Functional endoscopic sinus surgery with a left ethmoidectomy and frontal and maxillary antrostomy was also performed. Culture of the pus revealed Streptococcus intermedius. The follow-up MRI revealed resolution of subperiosteal and epidural abscesses (Figure 3).

Figure 1.

Sagittal CT of the brain with (a) bone window and (b) soft tissue window images shows erosion of the outer and inner cortices of frontal bone (arrow) with prefrontal soft tissue swelling (arrow).

Figure 2.

(a) Sagittal T2 fluid-attenuated inversion recovery and (b) axial contrast-enhanced T1-weighted images show frontal sinusitis (smaller arrow), frontal bone defect (curved arrow), and frontal epidural collection (longer arrow) with peripheral rim enhancement (larger double arrows) suggestive of epidural abscess. A small subperiosteal abscess is also noted in the frontal soft tissues (smaller double arrows).

Figure 3.

Postoperative postcontrast (a) axial and (b) sagittal MRI images show resolution of the extradural abscess and frontal sinus infection. The burr holes (arrows) are related to surgical evacuation of the abscess.

DISCUSSION

Pott puffy tumor is a rare clinical entity with the advancement in antibiotic treatment. Initially described with head trauma, now it is known to be associated with untreated or partially treated sinusitis; however, cases due to mastoid surgery, dental infections, wrestling injuries, and insect bites have been reported (2, 3). Pott puffy tumor can be found in all age groups, but occurs predominantly in adolescents (4). Frontal sinuses are often pneumatized by 2 years of age and are approximate adult size by the late teens. Venous drainage occurs through diploic veins that have communication with the dural venous sinuses, which can propagate septic emboli (4). These infections are often polymicrobial, with streptococci, staphylococci, and anaerobic bacteria, as they favor lower oxygen concentrations. Hence, antibiotic coverage should include gram-positive and anaerobes (5). In the present case, the organism was Streptococcus intermedius.

Symptoms include headache, periorbital swelling, fever, purulent rhinorrhea, vomiting, and signs of meningitis or encephalitis. Intracranial complications occur either due to direct extension or venous drainage. Complications include meningitis; epidural, subdural, or intraparenchymal abscess; and cavernous sinus and dural venous sinus thrombosis (5). If the inferior wall of the frontal sinus is involved, infection may spread to the orbits, causing either orbital cellulitis or intraorbital abscess (6).

Our patient presented with frontal swelling and headache in the emergency department and received a CT. Although CT scans have a higher radiation dose, at most centers like ours, MRI scanners are not available around the clock. Particular attention should be paid to decrease the radiation dose by strictly following the pediatric protocols for radiation dose reduction. A CT scan with contrast can be performed if there is a high suspicion of intracranial extension. Intracranial complications with or without direct erosion of the frontal bone have been observed in about 60% to 85% of these patients (5, 7). Tsai et al reported a 100% rate of intracranial complications in their six pediatric patients with Pott puffy tumor (8). Ketenci et al indicated that intracranial complications are often present during a regimen of antibiotics and are often asymptomatic when the abscess is localized in a silent area of the central nervous system (5, 9, 10).

CT scan can demonstrate sinusitis, bone erosion, subperiosteal collection, and intracranial extension. In our case, CT showed frontal sinusitis, bone erosion, subperiosteal collection, and extradural abscess. As with other intracranial pathologies, MRI is the modality of choice (11, 12). MRI can better delineate intracranial pathology, dural sinus thrombosis, and bone edema. Abscesses show restricted diffusion (13, 14) on diffusion-weighted sequences, indicating thick viscous pus. In this case, MRI showed frontal bone edema and extradural abscess, without dural venous sinus or meningeal involvement. MRI is helpful particularly in follow-up after medical or surgical management, reducing overall radiation exposure. Bone scintigraphy with Tc-mMP may be more sensitive than CT in detection of early osteomyelitis, but its sensitivity is poor in the setting of acute sinusitis (15).

Early diagnosis and treatment of Pott puffy tumor is necessary. Broad-spectrum antibiotics for 4 to 6 weeks, along with surgical drainage, is the standard of care. This patient underwent frontal craniotomy and functional endoscopic sinus surgery in addition to 4 weeks of antibiotics. Follow-up MRI showed complete resolution.