Volume 2, Issue 4 , Pages 218-221, December 2007
Calvarial tuberculosis: A rare complication of tuberculous mastoiditis
Article Outline
Summary
Tuberculous mastoiditis is a well-documented entity, but tuberculous osteitis of the skull is a rare phenomenon. The majority of cases of calvarial tuberculosis (TB) are secondary to pulmonary TB. The most common routes of infection are via the haematogenous or lymphatic route, but direct extension can also occur. We present a rare case of a 17-year-old male patient who presented with tuberculous osteitis of the skull complicated with sigmoid sinus thrombosis and an extradural abscess, following direct extension from tuberculous mastoiditis. Only one similar case has been reported in the literature. We review the world literature regarding this rare phenomenon.
Keywords: Mastoiditis, Osteitis, Tuberculosis
Introduction
Mycobacterium tuberculosis infection is a serious infection affecting about one-third of the world's population [1], and is the world's leading cause of death from a single infective agent [2]. Tuberculosis (TB) is an endemic illness in South Africa. The rising incidence in recent times is due to a number of factors of which poverty and HIV infection is the most important [2]. Tuberculous mastoiditis is a well-documented entity, but tuberculous osteitis of the skull is a rare phenomenon. Only one case report of tuberculous osteitis of the skull developing from direct extension from tuberculous mastoiditis has previously been reported [3]. Here we present a case of a 17-year-old male patient who presented with TB osteitis of the skull following direct extension from TB mastoiditis. We review the world literature regarding this rare phenomenon.
Case study
A 17-year-old boy presented to our department with a 2-week history of progressive right post-auricular swelling. He complained of minimal otalgia and slight hearing impairment. He had no otorrhoea, vertigo, headaches or previous otological problems.
On examination he was pyrexial (temperature 38.5
°C), with a fluctuant mass extending from the right post-auricular area to the occiput. There was mild tenderness over the affected area and his auricle was not displaced. On otoscopy his right tympanic membrane was inflamed with no evidence of a perforation. His facial nerve function was normal. He had a normal neurological examination and no evidence of meningitis.
Various special investigations were performed which included a normal white cell count, normal electrolytes and a negative HIV test. A contrast enhanced computed tomography (CT) scan demonstrated a right occipital scalp abscess infiltrating the muscle (Fig. 1). The abscess extended deep to the muscular layer with resultant osteitis and destruction of the occipital bone (Fig. 2, Fig. 3). The mastoid air cell system was opacified and there were signs of thrombosis of the right sigmoid sinus with a small extradural collection (Fig. 1). His brain was normal and there was no sign of raised intracranial pressure.
Fig. 1.
A contrast enhanced axial computed tomography (CT) scan demonstrating a right occipital scalp abscess (white arrow) with right sigmoid sinus thrombosis and an extradural collection (black arrow).
Fig. 2.
A coronal computed tomography (CT) scan demonstrating osteitis and destruction of the right occipital bone (white arrow) due to calvarial tuberculosis.
Fig. 3.
An axial CT scan demonstrating destruction of the right occipital bone due to calvarial tuberculosis.
The scalp abscess was drained through a post-auricular approach and a cortical mastoidectomy was performed. The mastoid air cells were filled with granulation tissue and there was a small amount of thick mucopus in the middle ear with an intact ossicular chain. The sigmoid sinus was exposed and the peri-sinus abscess was drained. The bony sequestra and osteitic bone were debrided. Biopsies of the mastoid granulation tissue and infected bone showed the presence of prominent granulomas but no acid fast bacilli were identified (Fig. 4, Fig. 5). Pus from the scalp abscess, mastoid cavity and sigmoid sinus abscess all confirmed the presence of TB bacilli. No other organisms were isolated.
Fig. 4.
Histology slide of tuberculous osteitis demonstrating a prominent granuloma in association with bone (H&E staining).
Fig. 5.
Tuberculous osteitis demonstrating a granuloma (H&E staining).
The diagnosis of tuberculous osteitis of the skull was made and the patient was started on anti-tuberculous treatment for 6 months. The patient was followed up at 1, 2, and 6 months and made a full recovery with normal hearing.
Discussion
Tuberculosis (TB) is the oldest documented infectious disease. Whilst once a common form of ear disease the incidence of TB otitis media and mastoididtis has declined since the turn of the previous century [4]. This is due to a number of measures, including the eradication of TB from milk; effective anti-TB therapy and BCG vaccination [4]. Although TB remained endemic in developing countries TB has emerged as a public health problem in developed countries as well, mainly as a result of human immunodeficiency virus (HIV) co-infection [5]. The incidence of pulmonary TB in the Western Cape of South Africa was 430/100,000 in 1998, but has risen to 832/100,000 in 2002, due mainly to the rising incidence of HIV infection [6]. The incidence of HIV infected individuals in 2002 in the local population was 12%. A study by Schaaf et al. showed that TB otitis media was more common in HIV-infected than in HIV-uninfected children [7].
TB affecting the bone occurs in approximately 1% of patients with mycobacterial infection [8]. Calvarial TB is a relatively unusual condition, with a reported incidence varying between 0.1% and 3.7% of all cases of skeletal TB [3], [8]. It is mainly a disease of children with 50% of patients below 10 years of age and 75–90% involving patients below 20 years of age [3], [8], [9].
It is thought that calvarial TB occurs via the haematogenous or lymphatic modes of transmission [3], [9]. The lymphatic route would appear to be the most likely as the skull has poor lymphatic supply and generous blood supply. This might explain the rarity of this condition [3], [9], [10], [11], [12]. Calvarial TB most commonly occur secondary to spread from a primary focus elsewhere in the body, usually pulmonary TB [3], [5], [8], [9]. Other primary sites include hilar, cervical, renal, gastrointestinal or central nervous system TB [8], [9]. In many cases no primary site can be found [9]. Direct extension from adjacent sites, for example orbit, paranasal sinuses, nasal mucosa and face has been described [10], [11], [13]. Only rarely has calvarial TB been described to result from direct extension from tuberculous mastoiditis, as in this case [3]. It has been postulated that minor trauma my be a predisposing factor in the development of bony lesions, due possibly to the unmasking of a latent infection, increased vascularity, decreased resistance, or the attraction of inflammatory cells to the area of trauma [3], [5], [8], [9].
Calvarial TB usually involves the frontal and parietal bones, followed by the occipital and sphenoid bones [5], [8], [9]. This is because of the greater amount of cancellous bone with diploe channels at these sites [5], [8], [9]. In the present case the occipital bone was mainly involved. Cranial sutures do not prevent the spread of infection and therefore considerable bony destruction may occur before a sinus or swelling occurs [8]. The tuberculous lesions begin in the diploe and can destroy both outer and inner tables of the skull [3]. The periosteum is usually spared. The lesions may be single or multiple and are pathologically divided into three types [5], [8], [9]. The circumscribed or perforating type which are small, circumscribed, punched out lesions of the skull that have little tendency to spread in the bone surrounding the defect. In the diffuse type there is widespread destruction of the inner table of the skull and when this is associated with extensive granulation tissue it is redefined as spreading-type lesions. The last and least common type is the circumscribed sclerotic type.
Calvarial TB usually present as a painless scalp swelling or a discharging sinus when the outer table is involved. [3], [9], [10], [11], [14]. Involvement of the inner table leads to the formation of extradural granulation tissue which may cause the development of neurological deficits [5], [8]. Despite the dura mater, which is an effective barrier to the spread of infection, calvarial tuberculosis with intradural involvement is occasionally observed in the form of meningitis, subdural empyemas, and cerebral tuberculomas [5], [8]. A recent case has been reported of calvarial tuberculosis causing sagittal sinus thrombosis, apparently the first case of this nature to be reported in the literature [5].
The present case demonstrates calvarial tuberculosis causing the rare complications of an extradural collection and sigmoid sinus thrombosis. The usual classic symptoms associated with tuberculous otitis media is painless discharging ears, severe conductive hearing loss, profuse granulation tissue on otoscopic examination and the presence of a facial paralysis associated with chronic otitis media in the absence of choleasteatoma [2], [4].
The isolation of acid fast bacilli (AFB's) from pus or tissue at the site of the lesion is diagnostic. These bacilli can be very difficult to isolate [14]. Occasionally if there is strong clinical suspicion without identification of TB bacillus, the patient can be started on anti-tuberculous treatment. A good response to anti-TB treatment will confirm the diagnosis. CT scans will demonstrate soft tissue swelling, destruction of one or both skull tables and the presence of bony sequestra. It will also demonstrate any intracranial spread of disease [9].
Treatment of calvarial TB includes both surgery and anti-tuberculous therapy. Anti-tuberculous therapy alone is sufficient for early localised lesions and improvement is usually seen after the second month of treatment [3], [5]. Surgery is indicated for obtaining tissue for histological analysis or for removal of bony sequestra. Other surgical indications include cases with large extradural collections causing neurologic deficits, associated sinus formation, large pockets of caseating material, associated fulminant secondary infection, or lack of response to treatment [5], [8], [9]. During surgery the involved bone and the extradural granulation tissue should be excised until normal bone is encountered. The dura mater should be left undisturbed [5], [8], [9].
The diagnosis of calvarial TB occurring as a result of spread from TB mastoiditis requires a high index of suspicion. It should be considered in any patient with an unusual presentation of mastoiditis, especially in patients living in an area where TB is endemic. Clinical suspicious features may include a painless post-auricular swelling or abscess and/or fistula formation. Bony destruction of the inner and/or outer tables of the skull, with or without intracranial complications are suspicious features on CT scan.
References
- . Tuberculosis in the upper aerodigestive tract and human immunodeficiency virus coinfections. J. Otolaryngol. 2003;32:320–323
- . Mycobacterium marches back. J. Laryngol. Otol. 1995;109:5–13
- . Radiology in focus, extensive calvarial tuberculosis: rare complication of tuberculous mastoiditis. J. Laryngol. Otol. 2004;118:65–68
- . Tuberculous mastoiditis: when is surgery indicated?. Int. J. Pediatr. Otorhinolaryngol. 2002;65:59–63
- . Superior sagittal thrombosis caused by calvarial tuberculosis: case report. Neurosurgery. 2007;60:E776
- South African Demographic and Health Survey, 1998, pp. 178.
- . Culture-positive tuberculosis in human immunodeficiency virus type 1-infected children. Pediatr. Infect. Dis. J. 1998;17:599–604
- . Calvarial tuberculosis. Neurosurgery. 1999;45:1345–1349
- Imaging features of calvarial tuberculosis: a study of 42 cases. Am. J. Neuroradiol. 2004;25:409–414
- . Tuberculous osteitis of the skull. Annals Trop. Paediatr. 1989;9:40–42
- . Tubercular osteitis of skull. Indian Paediatr. 1993;30:1119–1123
- . Tuberculous osteitis of the skull mimicking histiocytosis X. J. Pediatr. 1984;105:269–271
- . Multifocal skeletal tuberculosis presenting as osteitis and atlantoaxial dislocation. Indian Pediatr. 1995;32:1214–1219
- . Calvarial tuberculosis. J. Paediatr. Child Health. 1999;35:221–222
PII: S1871-4048(07)00051-2
doi:10.1016/j.pedex.2007.06.003
© 2007 Elsevier Ireland Ltd. All rights reserved.
Volume 2, Issue 4 , Pages 218-221, December 2007
