Spheno-Orbital Tuberculosis: A Rare Case

Abstract

A 9-year-old girl presented with progressive, painless protrusion of the right eye for 2 months. She also complained of multiple bilateral neck swellings for 2 months. On examination, there was proptosis of the right eye with the eyeball displaced downwards and forwards. The extra ocular movements of the right eye showed limitation of abduction. The vision was normal in both eyes. A detailed clinical evaluation with investigations led to a diagnosis of spheno-orbital tuberculosis. Prompt initiation of anti-tubercular therapy (ATT) led to resolution of the lesion.

Introduction

Spheno-orbital tuberculosis is a rare site of extra pulmonary tuberculosis. It may be due to direct spread from paranasal sinuses or by hematogenous spread 1. Its diagnosis is challenging and often delayed, especially in the absence of pulmonary and systemic signs or symptoms typical of tuberculosis 2. This article describes a rare case of spheno-orbital tuberculosis in a young girl.

Case Presentation

A 9-year-old girl presented with progressive, painless protrusion of the right eye for 2 months. On examination, there was proptosis of the right eye with the eyeball displaced downwards and forwards, with normal overlying skin (Fig. 1). The extra ocular movements of the right eye showed limitation of abduction. The vision was normal in both eyes. Neck examination revealed bilateral multiple enlarged cervical lymph nodes.

Fig. 1.

Proptosis of the right eye with the eyeball displaced downwards and forwards

Complete blood count, kidney function test, and liver function test were normal. Erythrocyte sedimentation rate (ESR) was 30 mm in first hour. Chest radiography revealed mediastinal lymphadenopathy. HIV (human immunodeficiency virus) test was non-reactive.

Computed tomography (CT) of the paranasal sinuses (Fig. 2) revealed permeative destruction of right sided sphenoid wing and squamous part of right temporal bone. An ill-defined lesion measuring 28 × 15 × 25 mm was seen in the extraconal compartment in supratemporal region of right orbit, reaching up to orbital apex and causing its widening. It showed lost fat planes with lateral rectus muscle and displaced it medially. It was extending into infratemporal fossa and showed loss of fat planes with muscles of mastication. Few necrotic lymph nodes were seen along left lower internal jugular vein and supraclavicular region, largest measuring 2.1 × 1.4 cm.

Fig. 2.

Computed tomography of the orbit: ill-defined soft tissue lesion in extraconal compartment in supratemporal region of right orbit, with the lesion reaching up to orbital apex, with destruction of right sided sphenoid wing and squamous part of right temporal bone

In view of suspicion of malignancy, the patient was advised whole body ¹⁸ F-fluorodeoxyglucose positron emission tomography computed tomography (FDG PET CT) scan. This revealed a partially necrotic heterogeneously enhancing FDG avid lesion in right infratemporal fossa with involvement of temporalis muscle and erosion of adjacent sphenoid bone (Fig. 3). It showed erosion of right lateral boy orbit with ipsilateral intra orbital extraconal extension. Few necrotic FDG avid lymph nodes were seen along left lower internal jugular vein and supraclavicular region, largest measuring 2.1 × 1.4 cm. multiple discrete and confluent necrotic and FDG avid lymph nodes were seen along right upper para tracheal, bilateral lower paratracheal, anterior mediastinal, subcarinal and right perihilar regions, largest measuring 3 × 2.4 cm.

Fig. 3.

Whole body PET CT scan of the patient

Fine needle aspiration cytology (FNAC) of the cervical lymph nodes showed caseating granulomatous lesion. The Ziehl-Neelsen stain was positive for acid fast bacilli (Fig. 4). Nucleic acid amplification test confirmed the presence of rifampicin-sensitive Mycobacterium tuberculosis. The patient was started on Category 1 Anti-tubercular therapy (ATT). After 10 months of ATT, the proptosis regressed with complete recovery of the extra ocular movements. On follow up CT scan, the patient showed complete resolution of the lesion (Fig. 5).

Fig. 4.

FNAC of the cervical lymph node

Fig. 5.

Follow up CT scan showing complete resolution of the lesion

Discussion

Due to its anatomical location, even benign lesions of the sphenoid can have significant morbidity and mortality. Sphenoidal tuberculosis can extend to the orbit, brain as well as cavernous sinus, and present with multiple cranial nerve palsies. Optic, oculomotor and abducens nerve palsies have been reported in literature 3. It is commonly associated with pulmonary tuberculosis. In our case, it was associated with tubercular cervical lymphadenitis.

Spheno-orbital tuberculosis may cause sclerotic and lytic changes in the sphenoid bone leading to skull base tubercular osteitis, or soft tissue involvement or both 3. As per literature, skull base tubercular osteitis as well as orbital tuberculosis is more commonly seen in children 3. It has a varied clinical presentation and there is difficulty in obtaining tissue samples, making its diagnosis a challenge. Furthermore, the sites of extra pulmonary tuberculosis are frequently paucibacillary, which complicates the identification of tubercle bacilli in the sample 4. In these cases, spheno-orbital tuberculosis may be misdiagnosed as malignancy. Its diagnosis is often based on high clinical suspicion, rather than a definite diagnosis and the response to treatment is often taken as confirmatory 5. In our patient, the skull base osteitis or orbital tissue was not investigated for direct evidence of tubercle bacilli. However, the detection of acid fast bacilli in cervical lymph nodes and nucleic acid amplification test confirmed the diagnosis of tuberculosis. The complete resolution of the symptoms following ATT further confirmed the diagnosis.

On computed tomography scan, it appears as a heterogeneously enhancing lesion with bone erosion and extension to surrounding areas. Magnetic resonance imaging 3 (MRI) may show a contrast enhancing mass lesion, isointense on T1, hyperintense on T2. Malignant and benign lesions such as invasive fungal sinusitis, eosinophilic granuloma, may produce similar clinical and radiological features and must be included in the differential diagnosis. Diagnosis of sphenoidal tuberculosis is based on high clinical suspicion and biopsy is confirmatory.

The management of spheno-orbital tuberculosis is ATT over a prolonged period of time. Duration of ATT ranges from 6 to 18 months as per literature 6. Surgery may be indicated for diagnosis or may be therapeutic or both.

Funding

No source of funding.

Declarations

Ethical statement

The study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki.

Informed Consent

Not required.

Conflict of Interest

No conflict of interest (for all authors).