A 14-year-old boy with cerebral palsy and severe global developmental impairment secondary to congenital rubella infection presented to a community hospital with new-onset mid-frontal forehead swelling. There was no associated fever, irritability or decreased energy. He had a one-month history of purulent nasal discharge, for which he was started on oral clindamycin and an antihistamine. The swelling progressed despite six days of treatment, and he was subsequently transferred to a tertiary care centre for further investigation and management.
On physical examination, the patient was afebrile and generally appeared well. A 3 cm by 4 cm fluctuant mass was evident on the mid-frontal forehead with no overlying erythema. Due to the patient’s underlying cognitive delay, it was difficult to assess whether the lesion was painful on palpation. Periorbital erythema and edema were also noted, although there was full range of motion of the extraocular muscles and no evidence of proptosis. Initial investigations included a complete blood count showing a white blood cell count of 9.1 ×109/L with a normal differential and an erythrocyte sedimentation rate of 49 mm/h.
Imaging studies confirmed the diagnosis.
A computed tomography scan of the head showing a defect in the left frontal sinus bone and an overlying abcess 135 mm × 135 mm in size (arrow)
CASE 2 DIAGNOSIS: POTT’S PUFFY TUMOUR
A computed tomography scan of the brain revealed opacified frontal sinuses with a bony defect of the left frontal sinus wall extending into an abscess overlying the frontal bone. These findings confirmed the diagnosis of Pott’s puffy tumour (PPT) suspected from the history and physical examination.
PPT is a rare but serious complication of acute bacterial rhinosinusitis (ABRS). First described by Sir Percival Pott in 1760, PPT refers to frontal bone osteomyelitis with an associated sub-periosteal abscess (1). Believed to be largely eradicated in the postantibiotic era, recent case series have highlighted that PPT remains a clinically serious entity that should prompt urgent intervention to prevent further clinical complications.
The ‘puffiness’ of the lesion is a result of the sinus infection spreading through the anterior table of the frontal bone and creating an abscess encapsulated between the bone and the periosteum (2). The spread of the infection is facilitated by the diploic veins, the vessels that drain the frontal sinuses, allowing for regional hematogenous spread to the frontal bone. The frontal sinuses approach adult size at between 12 and 13 years of age, while the vascularity of the diploic veins further develops during adolescence, leading to a peak incidence of PPT at this time (3). Reviews of the literature suggest a male predominance in the incidence of PPT (1,4). Although the phenomenon is most commonly associated with frontal sinusitis, PPT has been described in association with trauma, mastoiditis, malignancy, insect bites and acupuncture (3).
Presenting signs and symptoms are often indolent and, in addition to the classic frontal swelling, commonly include fever, cough, rhinorrhea and headache. Nausea, vomiting, lethargy or focal neurological deficits may suggest raised intracranial pressure secondary to intracranial spread of the underlying infection (1). Early diagnostic imaging with either computed tomography scanning or magnetic resonance imaging is vital in determining the extent of disease, as well as detecting additional intracranial complications of ABRS that can be associated with PPT such as subdural and epidural empyemas, brain abscesses and sinus thromboses.
Laboratory investigations are consistent with a bacterial infection including an elevated white blood cell count with neutrophilia. Inflammatory markers, such as erythrocyte sedimentation rate and C-reactive protein levels, are also elevated, but nonspecific. Cultures from the abscess in the setting of PPT may be polymicrobial and include Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae and Staphylococcus species, but may also grow microaerophilic Streptococcus species and other anaerobes due to the relatively hypoxic environment in the sinus and abscess (1).
Initial management of PPT generally involves incision and drainage and surgical debridement of infected bone and granulation tissue. More extensive sinus surgeries, such as endoscopic sinusotomies, may be required. Broad-spectrum intravenous antibiotics should be initiated and subsequently tailored to the sensitivities of the causative organisms. The total duration of antibiotic therapy is often based on the treatment of local osteomyelitis (approximately four to six weeks); however, the response to treatment and presence of additional intracranial complications must be taken into consideration (4).
Our patient was admitted to the hospital and taken to the operating room, where he underwent an incision and drainage of his frontal abscess. An indwelling catheter was inserted into the left frontal sinus and remained in situ during his admission. The patient was started empirically on vancomycin, levofloxacin and metronidazole because he had previously experienced severe adverse reactions to both penicillin and cephalosporins. Intraoperative cultures grew Streptococcus anginosus group and Parvimonas micra. The patient improved clinically and was discharged after one week, and was continued on levofloxacin and metronidazole to complete a total of six weeks of antibiotic treatment.
CLINICAL PEARLS
PPT is a rare but serious complication of ABRS.
Although the presenting signs and symptoms are nonspecific and indolent, the diagnosis of PPT should be suspected when frontal forehead swelling is observed in the setting of ABRS.
Diagnostic imaging is required to evaluate the extent of the disease because PPT may be associated with intracranial extension of the infection.
Management of PPT can involve a combination of surgery and antibiotic treatment tailored to the causative organisms.
