Calvarial tuberculosis: A rare localization of a common disease

Dear Sir,

We read an article entitled “Calvarial tuberculosis: A rare localization of a common disease” by Safia et al. ^[1] with great alacrity. Though tuberculosis is rampant in developing countries like India, calvarial tuberculosis is a rare entity and rarer still is primary calvarial tuberculosis.

We also came across a case of primary calvarial tuberculosis who presented to us with recurrent fluctuant, painless scalp swelling with sticky creamish discharge for 19 years, not amenable to antibiotic treatments and surgical excision. Nine years later, he developed generalized tonic clonic seizure (GTCS), which responded well to carbamazepine 300 mg bid. His neurological examination was within the normal limits, erythrocyte sedimentation rate (ESR) was raised (80 mm), mantoux test (MT) was strongly positive (25 mm × 20 mm), cerebrospinal fluid (CSF) showed lymphocytic pleocytosis and raised protein and magnetic resonance imaging (MRI)-brain showed osteolytic lesions with soft tissue components of right temporal, parietal and occipital bones with ring enhancing lesions in the occipital and parietal cortices and diffuse bony and meningeal enhancement [Figure 1]. Magnetic resonance spectroscopy showed a large lactate peak at 0.9 ppm and decreased N-acetyl-aspartate and creatine peak. Histopathological examination of deep mastoid bone was suggestive of chronic osteomyelitis. However, no acid-fast bacillus was demonstrated. Based on the above clinico-historical, radiological and histopathological features, raised ESR and strongly positive MT, possibility of calvarial tuberculosis with intracranial tuberculomas were kept and patient was started on standard antituberculous treatment. Further, as no primary focus was found on detailed work-up, possibility of primary calvarial tuberculosis with intracranial affection seemed more likely. The patient showed marked clinical and radiological improvement on follow-up [Figure 2], which further supported our diagnosis.

In the case discussed by author, patient had primary calvarial tuberculosis with discharging sinuses. Though patient did not have any neurological symptoms unlike ours, yet brain imaging, ideally MRI or at least contrast enhanced computed tomography-brain, should have been done not only to look for the extent of calvarial involvement but also to rule out intracranial pathologies, e.g., parenchymal granulomas or meningeal enhancement. Because, even in our case, the initial presentation was recurrent, painless, secreting scalp lesions for good nine years, only later to be followed by GTCS. Hence, this underlines the importance of early brain imaging. CSF examination is also important to pick up any occult meningeal infection.

Isolated calvarial tuberculosis is rare due to paucity of lymphatic and cancellous components in the calvarial bones. ^[2],[3] Frontal and parietal bones are more vulnerable owing to greater diploic space and cancellous component; ^[4] however, in our case temporal and occipital bones were the worst affected. Further, the association of intracranial tuberculoma with calvarial tuberculosis, like in our case, is very rare.

Isolation of tubercle bacilli is the gold standard for the diagnosis, but it is not always feasible. Hence recurrent, painless, secreting scalp swellings, not amenable to antibiotics and surgical treatments, are important clue to the diagnosis of calvarial tuberculosis; ^[5] especially if supported by imaging and other ancillary tests and a satisfactory therapeutic response, as in our case.

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1755-6783.146453

[Figure 1], [Figure 2]