Initial CT scan of the orbits
Head & neck imaging
Case TypeClinical Cases
Authors
Sofia Frade Santos, Alexandra Borges
Patient60 years, female
A 60-year-old woman presented with recurrent episodes of blepharitis and a painless hard lump in the medial canthus. There was no clinical improvement after treatment with several antibiotics and steroids. Fine-needle aspiration cytology revealed a granulocytic exudate. Ziehl-Neelsen stain was negative but cultures were positive for Mycobacterium tuberculosis.
An orbital CT scan showed a 2 cm soft-tissue mass in the inferomedial aspect of the right orbit, in a preseptal location, corresponding to the location of the lacrimal sac (figure 1a-d), accompanied by a diffuse thickening of the lower lid and minor dilation of the nasolacrimal duct (figure 1d), compared to the contralateral side. There was also faint stranding of the adjacent extraconal fat. The mass was isodense to muscle and relatively homogeneous on this non-enhanced CT scan. No changes were seen in the adjacent bone and there was no periosteal reaction. The nose and paranasal sinuses were normally aerated with no blockage of the inferior meatus. No enlarged lymph nodes were depicted.
Chest radiograph (figure 2) showed no relevant findings, particularly there were no signs of active pulmonary tuberculosis.
Background
Primary tuberculous dacryocystitis is a rare form of oculo-adnexal TB [1,2].
Tuberculosis of the lacrimal apparatus may be primary or secondary to haematogenous spread, direct spread from the sinonasal or orbital region or still by a hypersensitivity response. Therefore, exclusion of systemic TB, particularly pulmonary, is mandatory [1,3].
Tuberculous dacryocystitis presents as a non-tender or mildly painful medial canthus swelling and epiphora[1]. This clinical presentation is unspecific, shared by other infectious, inflammatory and neoplastic causes of nasolacrimal obstruction[3]. Diagnostic hints include an insidious onset, longstanding symptoms refractory to conventional treatment, previous history of TB or contact with a TB patient and the presence of fistulous/sinus tracts[1].
Diagnosis requires a high degree of suspicion. Cultures remain the gold-standard for diagnosis but their sensitivity in this extrapulmonary location is compromised by the paucibacillary nature of the disease [1,2]. Acid-fast bacilli staining (Ziehl–Neelsen), Mantoux and/or IGRA (interferon-gamma release assay) test and PCR (polymerase chain reaction) also have variable sensitivities. Histopathology typically shows a chronic granulomatous inflammation with caseating necrosis. In difficult cases, diagnosis can be corroborated by a favourable response to antibacillary agents [2-4].
Treatment of tuberculous dacryocystitis is with a 6-18 months course of anti-tubercular therapy [4-7].
Imaging Perspective
Cross-sectional imaging is mandatory to assess the exact location and extent of the disease and to differentiate the 5 different forms of orbito-adnexal TB: classical periostitis, orbital soft tissue tuberculoma without bone destruction, orbital TB with bone involvement, orbital spread from the paranasal sinuses and TB of the lacrimal apparatus [4, 8-10]. Imaging is crucial to depict disease extent. Intravenous contrast should be given to highlight the inflammatory changes, depict abscess formation and fistulous tracts [9]. Chest radiograph or CT of the chest is mandatory to rule out signs of pulmonary TB [1].
Outcome
Anti-bacillary treatment was initiated, including four antibiotics (isoniazid, rifampicin, pyrazinamide, and ethambutol) for the initial phase followed by isoniazid plus rifampicin for the maintenance phase. There was a good clinical and radiological response to treatment (figure 3).
Take-Home Message
Written informed patient consent for publication has been obtained.
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URL: | https://www.eurorad.org/case/17591 |
DOI: | 10.35100/eurorad/case.17591 |
ISSN: | 1563-4086 |
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