| Abstract|| |
Calvarial tuberculosis (TB) is a rare manifestation of extra-pulmonary TB, scantily reported in literature and accounting for 0.2% -1.3% of all cases of skeletal TB. The incidence of calvarial TB is rare, even in developing countries where TB is endemic. We describe a case of skull TB in a 16 year old male presenting as scalp swelling with a sinus in the occipital region. The diagnosis was established on histo-pathological examination with demonstration of Acid Fast Bacilli.
Keywords: Calvarial, scalp swelling, tuberculosis
|How to cite this article:|
Safia R, Zeeba J, Sujata J. Calvarial Tuberculosis: A rare localisation of a common disease. Ann Trop Med Public Health 2013;6:309-11
|How to cite this URL:|
Safia R, Zeeba J, Sujata J. Calvarial Tuberculosis: A rare localisation of a common disease. Ann Trop Med Public Health [serial online] 2013 [cited 2020 Jan 26];6:309-11. Available from: http://www.atmph.org/text.asp?2013/6/3/309/120991
| Introduction|| |
Mycobacterium tuberculosis infection is still endemic in developing countries. With the resurgence of immuno-compromised states like Human Immuno-deficiency Virus (HIV) infection, the incidence of TB is ever increasing. It can involve almost any part of human body. However, one such albeit rare extra-pulmonary manifestation is TB of calvaria. Involvement of the calvarium in tubercular disease is rare and even rarer is primary calvarial TB.  Tuberculosis affecting bones account for 1% of all tuberculosis infection  and of these, only 0.2% -1.3% comprise skull involvement.  This rarity may be attributed to deficiency of lymphatics in the calvarial bone, thereby lack of spread from primary focus. 
We discuss this in scantily described condition in a 16 year old male presenting with a scalp swelling and a discharging sinus.
| Case Report|| |
A 16 year old male presented to the surgical out-patient department with a painless scalp swelling and a discharging sinus in the occipital region. There was history of headache for the past one and a half month. However, no history of seizures suggestive of neurological symptoms was elicited. On examination, patient was afebrile, a soft, non-tender, non-pulsatile scalp swelling measuring 3×2cm was seen along with a discharging sinus, localized to the occipital region. Laboratory investigations indicated anemia hemoglobin 9.3 gm/dl, total leucocyte count was 7100/mm 3 alongwith an erythrocyte sedimentation rate of 60 mm/hr. Routine chest roentgenogram (PA view) was normal. Radiograph of the skull was nonspecific, erosion of the bone underlying the swelling was suspected. Computerized scan was advised, however due to paucity of funds the patient could not afford the investigation. Fine needle aspiration of the swelling yielded only necrotic debris with no viable cells.
Surgical intervention was indicated for diagnostic purposes and excision of the swelling with sinus along with bony debridement was done. Excised tissue and the curetting were sent for histopathological evaluation. Microscopic examination of soft tissue and bony curettings revealed areas of necrosis, diffuse infiltration by polymorphs and lympoplasmacytic infiltrate [Figure 1]. Presence of epitheloid cell granulomas with Langhan's giant cell [Figure 2] and necrotic material was diagnostic. Acid fast bacilli were demonstrated on Ziehl Nielson staining thereby confirming the diagnosis of tuberculosis. A definitive diagnosis of granulomatous lesion of tubercular etiology was made.
|Figure 1: Microsection from bony debridement showing marked areas of necrosis (H and E, ×10)|
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|Figure 2: Microsections showing numerous Langhan's giant cells, epitheloid cells and necrotic areas (H and E, ×40)|
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The patient was managed accordingly and anti-tuberculosis therapy was started. Patient has since been in follow up and has shown good clinical recovery.
| Discussion|| |
Calvarial tuberculosis constitutes a rare disorder even amongstthe communities withhigh incidence of TB infections.It was first described by Reid in 1842.  Primary event in the pathogenesis of most of the cases is lodging of infection secondary to haematogenous spread from an extra-calvarial focus. ,, However, isolated calvarial T.B. is seen rarely. In the present case also no evidence of a tubercular focus elsewhere was identified.
Trauma has also been incriminated as a possible cause of skeletal TB. The possible mechanisms include rich vascular supply of the skull bones or low resistance or un-masking of latent infection by trauma. , A detailed history of our case did not contribute to any evidence suggestive of trauma.
The younger population is at a higher risk of developing calvarial TB with majority of the patients (75%-90%) being under 20 years of age, , as it is in the present case. This condition is rarely seen in infancy possibly due to paucity of cancellous bone in the infants.  The disease is observed to affect both sexes equally with no sexual predilection.
Early clinical signs are usually absent in this disease and the appearance of a painless fluctuant swelling is the most common presentation and usually the first symptom. , A soft swelling of the scalp with erosion of the underlying bone is very characteristic.  The most common sites of involvement are frontal and parietal bones and less in the occipital bone.  The clinical finding suggestive of intracranial extension such as seizures, meningitis, venous sinus thrombosis are rarely observed. Our patient had presented with an occipital scalp swelling with a discharging sinus with no evidence of neurological findings.
Calvarial T.B. may present clinically as an isolated scalp swelling with paucity of systemic signs. Montoux test and raised erythrocyte sedimentation rate (ESR) are good markers and may give diagnostic clue to TB. However, Montoux test may be negative in 10%patients, while the ESR may be normal in similar number of patients.  Radiological findings which are very valuable tools to reach a diagnosis, are known to be variable and nonspecific, as seen in the present case, and are thought to be only suggestive but not diagnostic.  CT scan and magnetic resonance imaging are recommended to assess extent of bone involvement, scalp swelling and the degree of intracranial extension. Demonstration of acid fast bacilli (AFB) in the smears or biopsy specimens, is diagnostic, but due to severe necrosis in some specimens AFB may not be demonstrable in many cases, as seen in literature, when Mycobacterium tuberculosis PCR provides the definitive diagnosis. We arrived at the diagnosis of tuberculosis in our patient on the basis of clinical findings, raised ESR, suggestive radiological finding and conclusive histo-pathological evidence alongwith demonstration of AFB on biopsy tissue.
The management includes predominantly anti-tubercular therapy (ATT) and surgery. Surgical management by debridement and curettage alone showed good results before the advent of ATT.  Surgery is indicated for diagnosis, for removal of large sequestrations or epidural collections, for patients with discharging sinuses or large collections of caseating material leading to mass effect or increased intracranial pressure. Recent studies advocate that combination therapy (ATT and surgery) is better as extensive areas of diseased bone may be source of tubercle bacilli unless surgically excised. , Prognosis depends upon gravity of the associated tuberculous lesion and local extent of the disease.
To summarize, calvarial tuberculosis is a rare presentation of a common disease. Scalp swelling is the commonest clinical finding and evidence of systemic tuberculosis may not be present in all the cases. Laboratory and radiological findings serve as a good marker, especially when there is high index of suspicion. Definitive tissue diagnosis alongwith demonstration of AFB, however remains the gold standard.
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Associate Professor, Department of Pathology, Hamdard Institute of Medical Sciences and Research, New Delhi - 110062
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]