| Abstract|| |
Orbital pseudotumors are inflammatory lesions of the orbit of unknown etiology, which clinically and radiologically mimic an orbital neoplasm. Fine needle aspiration cytology (FNAC) is a useful tool in evaluating patients with presumed pseudotumors. We are presenting here a case of an orbital pseudotumor that was diagnosed with the aid of FNAC. A 43 year-old male presented with a complaint of unilateral proptosis in the right eye that had developed a year ago. Differential diagnoses of lymphoproliferative disorder and malignancy were considered after radiological evaluation. FNAC revealed features suggestive of reactive lymphoid hyperplasia and a diagnosis of an orbital pseudotumor was suggested that was confirmed later by histopathological examination. We report this case to emphasise the usefulness of FNAC in providing invaluable diagnostic information for proper clinical management. Thus, FNAC may save the patient the inconvenience of unnecessary exploratory orbital surgery.
Keywords: Fine needle aspiration cytology; orbital pseudotumor, inflammatory.
|How to cite this article:|
Agarwal A. Orbital pseudotumor: Diagnosis on fine needle aspiration cytology. J Cytol 2008;25:67-9
| Introduction|| |
Orbital pseudotumor, also known as idiopathic orbital inflammation, is defined as a nonspecific inflammatory process of the orbit without any identifiable local or systemic causes. This is a rare disease that simulates a neoplasm both clinically and radiologically. Fine needle aspiration cytology (FNAC) is a useful tool in evaluating patients with presumed pseudotumors. The procedure is simple, requires only topical anesthesia and provides invaluable diagnostic information that is very useful for proper clinical management. FNAC may save the patient the inconvenience of unnecessary exploratory orbital surgery. We present here a case of an orbital pseudotumor that was diagnosed with the aid of FNAC.
| Case Report|| |
A 43 year-old male presented with a complaint of unilateral proptosis in the right eye that had developed a year ago [Figure 1]. There were no associated ocular or systemic symptoms. Results of initial investigations to find a cause for the proptosis were within normal limits; his thyroid functions were essentially normal.
A computed tomography (CT) scan of the orbit was performed which revealed ill-defined intra and extraconal lesions in the right orbit with diffuse enlargement of the left lacrimal gland and mild thickening of the extraocular muscles [Figure 2a]. A diagnosis of lymphoproliferative disorder-lymphoma was considered.
A magnetic resonance imaging (MRI) scan of the orbit revealed an infiltrative retrobulbar lesion in the right orbit with ill-defined outlines of the right superior rectus, superior oblique and inferior oblique muscles, and was in proximity to (but not involving) the optic nerve [Figure 2b]. Differential diagnoses of lymphoma and malignancy with pansinusitis were offered.
Fine needle aspiration cytology of the orbital lesion revealed highly cellular aspirates, showing a mixed population of lymphoid cells comprising of small lymphocytes, centrocytes, centroblasts, and plasma cells. No epithelioid cells or granuloma were seen. The features were suggestive of reactive lymphoid hyperplasia [Figure 3] and hence, a diagnosis of inflammatory pseudotumor of the orbit was made.
The patient was put on steroid therapy. He responded initially to the therapy but subsequently developed steroid-induced diabetes. He later underwent right lateral orbitotomy surgery at Sankara Nethralaya, Chennai. Exploration of the orbit was performed but revealed no well-defined masses. Multiple biopsies were taken whose histopathological investigation was suggestive of an idiopathic orbital inflammation, confirming our diagnosis of an inflammatory pseudotumor of the orbit made with the aid of FNAC.
| Discussion|| |
An inflammatory orbital pseudotumor is a nongranulomatous inflammatory process in the orbit with no known local or systemic cause,  the condition being first described in 1905 by Birch-Hirschfeld.  After Grave's disease and lymphoproliferative disorders, an inflammatory orbital pseudotumor is a common ophthalmologic disease among orbital disorders.  The disease usually occurs in adults but may also affect children. Pediatric orbital pseudotumors account for 6–16% of orbital pseudotumors. 
Clinical symptoms are primarily proptosis, diplopia, decreased ocular mobility, and pain. The symptoms are a reflection of the inflammatory response and the location of the inflammatory tissue. Mechanisms ranging from autoimmunity, infections to poor wound healing have all been proposed to account for the development of pseudotumors. The end effect is an inflammatory infiltrate occupying space and compressing tissues, vessels, and nerves with a mass-lesion effect similar to a true tumor. The disease is believed to be self-limiting and benign in nature but can cause serious ocular damage and severe visual deterioration may occur in approximately 5% of the cases due to optic nerve compression.  The disease is typically unilateral and may be recurrent. However, this condition may be commonly bilateral in children. The differential diagnoses include orbital cellulitis, thyroid ophthalmopathy, sarcoidosis, lymphoid tumor, lymphangioma, and metastatic carcinoma.
Orbital pseudotumors have no distinctive characteristics, either clinically or radiologically. The radiological evaluation consists of CT and MRI scans. CT reveals orbital pseudotumors as a nonspecific focal or diffuse soft tissue mass, which is poorly demarcated and enhances variably after administration of iodinated contrast material.  MRI shows a hypointensity on T1– and T2–weighted images, with marked gadolinium enhancement. 
Fine needle aspiration biopsy is useful in evaluating patients with presumed orbital pseudotumors. The procedure can be performed under ultrasound or CT guidance. In experienced hands, the success rates have been high and the complications rare and minor. FNAC can also be used if recurrence of orbital tumor is suspected and a new mass is seen on a CT scan. In a case series, 38 patients with orbital lesions underwent FNAC under CT guidance. No false-positive results were observed. Negative results were observed in 10% of fine needle aspiration biopsies. Lymphomas could be differentiated from pseudotumors in all patients in this series. Flow cytometry or Southern blot analysis could be performed on these cytopathologic specimens and was useful in selected cases. 
Histologically, orbital pseudotumors are divided into acute, subacute, and chronic forms. These divisions are based on the degree of inflammatory and fibrovascular responses. In the acute form, there is a polymorphous inflammatory infiltrate composed of lymphocytes, plasma cells, macrophages, eosinophils, and rarely neutrophils within a loose fibrous stroma. Multinucleated foreign body giant cells secondary to fibrosis have also been described, but are rare. Tissue that is more fibrous is seen in subacute and chronic situations. Children may exhibit a heavy eosinophilic infiltrate. 
Initial treatment of inflammatory orbital pseudotumors is with high-dose corticosteroids. An acute form is usually extremely steroid-responsive and was, at one time, considered to be a diagnostic finding. Improvement typically occurs within 48 hours of steroid initiation. It must be cautioned, however, that malignant disease may also show a transient response to steroid treatment. Abrupt recurrence upon discontinuation of steroids is not characteristic of orbital inflammatory pseudotumors and, therefore, less benign processes should be sought out. Radiotherapy should be used if there is no improvement with steroid administration and if symptoms progress.  Surgery may be indicated when other methods have failed. Other immunosuppressant agents have achieved some anecdotal success.
In conclusion, accurate diagnosis of an inflammatory orbital pseudotumor remains the biggest challenge in its management. FNAC is a useful tool in evaluating patients with suspected orbital pseudotumors, and may yield valuable diagnostic information, thus obviating major surgical procedures in a substantial number of patients.
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Military Hospital, Saugor - 470 001, Madhya Pradesh
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2a], [Figure 2b], [Figure 3]