Imaging features of calvarial tuberculosis: a study of 42 cases

Abstract

Background and purpose: Tuberculosis of the calvaria is a rare entity, and only anecdotal reports describing its imaging features have been previously published in the literature. We report the role of conventional radiography and CT findings on in the evaluation of calvarial tuberculosis in 42 cases.

Methods: Forty-two cases of pathologically verified calvarial tuberculosis were analyzed retrospectively by using conventional radiography and CT imaging. The patients included 28 male and 14 female subjects ranging in age from 5 to 48 years (mean age, 16 years). Surgery was performed in 28 patients, and the remaining 14 patients underwent fine needle aspiration cytology. The histologic findings were consistent with the diagnosis of tuberculosis. At follow-up after 2 years, all patients had completely recovered.

Results: The male-to-female ratio was 2:1 (28 male and 14 female). The maximum number of patients affected by calvarial tuberculosis ranged in age from 11 to 20 years (61.2%). The average duration of symptoms was 2.5 months. Thirty-nine (92.8%) patients had subgaleal soft tissue swelling, whereas 31(73.8%) patients had a well-defined lytic lesion in the calvaria. The parietal bone was most commonly affected site of the calvaria (ie, in 22 patients [52.4%]). These lesions were detected at conventional radiography in 34 (80.95%) patients. CT depicted bone destruction in 36 patients (85.7%) cases. Extradural lesions and intraparenchymal pathologies were detected in 22 (52.3%) patients and 5 (11.9%) patients, respectively.

Conclusion: In calvarial tuberculosis, conventional radiographs of the skull show focal bone destruction often with accompanying soft tissue opacity. CT helps in assessing the extent of bone destruction, scalp swelling, and degree of intracranial involvement. Surgery involving bone debridement is resorted to only in cases where bone destruction is extensive.

Fig 1.

Lateral radiograph shows large circumscribed lytic lesion in frontal bone.

Fig 2.

Anteroposterior radiograph demonstrates a large frontoparietal lytic lesion suggestive of diffuse spreading type.

Fig 3.

Frontal radiograph shows a lytic lesion with a sclerotic margin.

Fig 4.

A, Contrast-enhanced axial CT scan shows peripherally enhancing epidural collection in left frontal region with bone defect and scalp swelling. B, Axial CT with a bone window shows left frontal calvarial defect destroying both inner and outer tables. Note the bony sequestration.

Fig 5.

Contrast-enhanced coronal CT scan shows right frontal epidural collection with subgaleal soft tissue. Note the circumscribed area of encephalomalacia of CSF attenuation.

Fig 6.

A, Coronal CT scan demonstrates a peripherally enhancing epidural collection over parietal region, crossing the midline associated with subgaleal soft tissue. On subsequent imaging, superior sagittal sinus showed no evidence of filling defect. The sinus tract is seen. B, Coronal bone window demonstrates destruction of right parietal bone.

Fig 7.

A, Axial T1- weighted MR image shows a predominantly isointense lesion in the right parietal bone. The hypointensity within it is suggestive of sinus tract. A streak of hyperintensity is also seen in the epidural region. B, Axial T2-weighted MR image shows the hypointense lesion in the right parietal bone. The epidural collection is hyperintense. C, Axial T1-weighted contrast-enhanced MR image shows diffuse enhancement of the calvarial lesion.

Fig 8.

Histopathologic analysis (Ziehl Nelsen stain) of surgical specimen obtained from the lesion showing multiple epitheloid granulomas with central caseation and palisade epitheloid cells (white arrowhead) with Langerhans giant cells (white arrow). Magnification ×100.