Role of fine needle aspiration cytology in the diagnosis of orbital masses: A study of 41 cases

Abstract

Background:

Complexity in the anatomy of orbit and the fear of globe rupture are the main challenges faced in the diagnosis and typing of orbital masses. Fine needle aspiration cytology can be used as an initial investigative procedure in the evaluation of orbital masses, which in turn can aid the clinician to plan the treatment modalities. A close cooperation between ophthalmologist and pathologist adds to the success of the procedure.

Aim:

The study was conducted in an attempt to evaluate the role of fine needle aspiration cytology (FNAC) in the diagnosis of orbital lesions as a cost-effective diagnostic technique, and to assess its diagnostic efficacy by comparing it with histopathological diagnosis.

Materials and Methods:

The study was conducted on 50 patients, over a period of 3 years, who had presented with anterior orbital mass lesions with or without proptosis, and with those having accessible mass lesions. Patients with proptosis without anterior orbital masses, proptosis due to dysthyroid ophthalmopathy, arteriovenous fistulas, hamartomas and choristomas were excluded from the study. FNAC procedure was done after explaining about the procedure to the patient, and in the presence of an ophthalmologist.

Results:

Majority of patients belonged to the age group 50-59 years. Male: female ratio was 1.05: 1. The most common lesion on FNAC was non-Hodgkins lymphoma, [13 cases (31.7%)]. 11 (26.8%) cases out of this were confirmed to be non-Hodgkins lymphoma on histopathologic examination. Two cases turned out to be inflammatory pseudotumor.

Conclusions:

FNAC can be done in all palpable orbital mass lesions with minimal risk and complications, with close cooperation between ophthalmologist and pathologist. A good degree of correlation was obtained between FNAC and histopathology, which was assessed by kappa statistics.

Introduction

The diagnosis of orbital lesions have always been a challenge to the clinicians because of the difficulty in surgical procedures involved in the biopsy of orbital lesions, especially in the deep or posterior aspect. The complexity in the anatomy of orbit contributes mainly to this difficulty. The concept of fine-needle aspiration cytology (FNAC) was proposed by Martin and Ellis[1] at Memorial Hospital, USA, in 1927. Subsequently it began to flourish in Scandinavia during 1950's and 1960's. Schyberg first used fine-needle aspiration biopsy for diagnosis of orbital tumors in 1975. FNAC is now widely used for investigating orbital masses. Limitations of FNAC of orbital lesions include the following:

1. Difficulty in reaching the lesion accurately, due to the special anatomy of the site.[2]

2. Accuracy of diagnosis may be affected by the insufficiency in the amount of material aspirated by FNAC.

3. Complications such as damage to globe, optic nerve, retrobulbar hematoma, and ptosis.[2,3]

However, the use of computed tomography (CT) and ultrasonography in localizing orbital lesions and immunostaining methods offer greater diagnostic accuracy in orbital lesions.[2,3,4]

Materials and Methods

Patients who presented to the outpatient department with orbital mass lesions accessible for FNAC, without the aid of ultrasonography or computed tomography (CT), and with or without proptosis, during a period of 3 years were selected for FNA, after discussion with the ophthalmologist.

Patients having proptosis without obvious anterior orbital mass lesions, proptosis due to dysthyroid ophthalmopathy, patients with clinical evidence of orbital varices and arteriovenous fistulas, children and adults with clinically obvious hamartomas and choristomas were excluded from the study. The procedure, its safety, potential complications, its limitations and the need for a biopsy after FNAC were explained in detail and a written consent obtained from each patient. The aspirations were done in the presence of an ophthalmologist. The needle used was 23 G, 1½ inch needle with attached 10 mL syringe. The aspirated material was expressed on to a clean labelled glass slide immediately, and thin smears prepared. The slides were fixed immediately in 95% alcohol and stained by the Papanicolaou method. Dry fixed smears were stained by May-Grünwald-Giemsa method. The smear findings were correlated with histopathology, at a later time after receiving the biopsy or gross specimen. Cell blocks were also made whenever adequate material was available. The results obtained were analyzed and compared, and the degree of agreement between FNAC and histopathology was assessed using kappa statistics.

Results

Of the 50 cases, 41 cases underwent histopathological examination. Among the 41 cases, 2 cases could not be diagnosed correctly by FNAC.

A majority of patients belonged to the age group 50-59 years (10 cases, 24.3%). Among these patients 21 (51.2%) were males and 20 (48.8%) females. Male:Female ratio was 1.05: 1.

Upper eyelid was involved in 24 cases (58.5%) and the lower in eight cases (19.5%). Both eyelids were involved in one case (2.4%) and other sites as cornea, conjunctiva, vitreous humor, and iris were involved in eight cases (19.5%).

The most common lesion on cytology was non-Hodgkins lymphoma [Table 1], [13 cases, (31.7%)]. Eleven (26.8%) cases out of this turned out to be non-Hodgkin's lymphoma on histopathologic examination [Table 2]. The cytology smears of non-Hodgkin's lymphoma showed a monotonous population of lymphocytes, slightly larger than small lymphocytes, with round nuclei having coarse granular chromatin. Nucleoli were absent [Figure 1]. Mucous retention cyst and mucocoele were diagnosed by the presence of clusters of mucinophages and scattered neutrophils and lymphocytes. The smears of inflammatory pseudotumor showed predominantly mature lymphocytes with round nuclei, scattered histiocytes, benign spindle cells and plasma cells. The smears of sebaceous carcinoma showed discohesive clusters of pleomorphic cells with abundant eosinophilic vacuolated cytoplasm and pleomorphic nuclei with prominent nucleoli [Figure 2]. The cytology of pleomorphic adenoma of lacrimal gland showed clusters of spindle shaped mesenchymal cells and fibrillary chondromyxoid ground substance. Benign spindle cell neoplasms were diagnosed by the presence of spindle cells with moderate amount of eosinophilic cytoplasm and oval nuclei without atypia and mitosis. Malignant melanoma of choroid showed pleomorphic cells with brownish pigment in the cytoplasm and round nuclei.

Table 1.

Cytological Observations

Table 2.

Histopathological observations

Figure 1.

Cytology smear of a case of NHL. (Pap, ×100)

Figure 2.

Cytology of the case of sebaceous carcinoma. (Pap, ×100)

Among chronic inflammatory lesions, the cytology smears in the case from which dirofilaria was removed during surgery, showed sheets of macrophages, many eosinophils, lymphocytes and few neutrophils. Another case showed filaments of fusarium. The filaments were slender, non-septate, branching at right angles to parent hyphae [Figure 3]. Conidiophores were also seen. The diagnosis was confirmed by culture.

Figure 3.

Cytology smear showing hyphae and conidophore of fusarium (Pap, ×400)

Finally, comparing results of FNAC with histopathology [Table 3], a good degree of agreement by kappa statistics was obtained for each class of lesions studied. Kappa values were 0.883 for NHL, 0.844 for other malignancies, 1 for benign neoplasms and cystic lesions, and 0.765 for inflammatory lesions.

Table 3.

Comparison between results of FNAC and histopathology

Discussion

FNAC had been used in the diagnosis of orbital masses since 1970s. The wide range of possible lesions in this anatomical area, their relative rarity and difficulties in direct surgical approach encourages the use of FNA biopsy in the diagnosis of these lesions.[5] The main limitations of the procedure include the varying sensitivity (50-98%) and the possible complications as globe rupture, hemorrhage and ptosis.

In the present study, FNAC was done on 50 patients and 41 cases underwent subsequent histopathological examination. Of the 41 cases, 2 cases were inconclusive by FNAC. So the positive identification rate was 87.8%. The diagnostic accuracy of the technique varies from 80% to100% in the literature.[6] The accuracy of diagnosis depends on the combination of expertise of performing physician and assistance of a competent cytopathologist.

So FNAC is a cost-effective, reliable and accurate method of diagnosing orbital masses in children and adults. It is needed to distinguish between inflammatory and neoplastic lesions, between benign and malignant lesions and epithelial and mesenchymal lesions. It is also useful in diagnosing an unresectable malignant neoplasm; thus eliminating the need for further surgical interventions.

Since the FNA was always done with the presence or help from an ophthalmologist, complications like bleeding, injury to eyeball, orbital muscles or lids, and infections did not occur in any of the patients. This emphasizes the need for aseptic precautions and reassurance to the patients about the procedure. As orbital contents and lesions are painful, it is always advisable to use local anesthetic before FNAC. This reassures the patients and helps in reducing ocular movements during FNA. In two children, the FNA was performed under general anesthesia. The preoperative FNA diagnosis of malignant lesions like sebaceous carcinoma helped the surgeons to plan the excision with adequate margins but not too radical a surgery, so that lid repair and oculoplasty procedures could be performed in a better way with better results.