This study presents the largest series of patients with SFCG, improving the medical record data regarding this disease. The granuloma is a result of chronic inflammatory reaction. Synthetic fibers and hair exhibit good histocompatibility. Therefore, they will induce local chronic inflammation that is different from acute inflammatory reaction caused by bacteria when they embed in the underlying stroma and are encapsulated by mucous. Local chronic inflammation is usually asymptomatic. In addition, the mass mainly occurs in the inferior eyelid fornix . Thus, patients rarely have ocular irritation symptoms, it is not easy to identify, and is often an occasional finding.
Prior studies have demonstrated a strong relationship between the lesions and various other objects containing synthetic fibers, including pullover sweaters, bedding, and blankets [3,4,7]. In our study, the etiology was identical to prior reports. Therefore, we believe avoiding close exposure to potential primary sources of synthetic fibers is crucial for preventing inflammatory granuloma growth.
SFCG was first reported by Weinberg et al. (1984) in a case series of 5 patients . To date, 20 additional patients with conjunctival foreign body granulomas caused by synthetic fibers have been reported (PubMed database research, Table 2). As reported in these cases, the lesions were usually unilateral and mainly in the inferior fornix . Compared to adolescents, children usually have a higher incidence of granulomas because they are more likely to be exposed to stuffed animals . The ages of patients in the published cases ranged from 26 months to 17 years old [1,2]. Based on the reviewed literature, including ours, the most common clinical symptom of SFCG is longstanding foreign body sensation; however, the majority of patients most often neglect the symptoms, which typically were present from many weeks up to a few months after exposure [3,6,7,9]. Patients are usually referred to the hospital because of an occasional finding of a mass in the eye. It is usually recognized weeks or months after lesion formation. Of all the cases, only one patient reported by Farooq et al. presented with ocular irritation in her left eye . They found the girl had developed severe keratitis and corneal ulceration. In our case series, in addition to foreign body sensations, other symptoms or signs including lumps and slight pain have been reported, and no other discomfort or ocular symptoms were demonstrated.
Schmack et al. reported that the presence of a unilateral inferior conjunctival mass was the most reliable clinical sign indicating SFCG .In contrast to clinical signs, the histologic features of SFCG are much more characteristic and diagnostic. Synthetic fibers can be confirmed by their relatively uniform size, strong birefringence under polarized light, and black granular spots. The characteristic histological features of large amounts of inflammatory cells including lymphocytes, plasma cells, eosinophils, and neutrophils presenting around the fibers supported the diagnosis of SFCG. Schmack et al. reported that the differential diagnosis of synthetic fiber conjunctival granuloma should include ophthalmia nodosa (insect and plant hairs), ligneous conjunctivitis, chalazion, pyogenic granuloma, dermoid, papillary hyperplasia, atypical dermoids or dermolipoma, or neoplasms such as rhabdomyosarcoma and vascular tumors [2,4,11] Many ophthalmologists may diagnose conjunctival masses as conjunctival dermoids because of their appearance. Although conjunctival dermoid presents as a mass with fine hairs adhering to the conjunctival fornix, the STR analysis could demonstrate that the inside hair is homologous with the mass, which is the primary difference between synthetic fiber conjunctival granuloma and conjunctival dermoid. The histopathologic and immunohistochemistry findings could also assist with correct diagnoses.
All of the microscopic examinations of our patients’ specimens revealed similar results, except in 2 cases. The foreign bodies found in these cases had not been described in previous literature. We could not clearly identify the foreign bodies but noted that they were surrounded by granulomatous inflammatory reactions. We suspect they were synthetic fibers that were not previously identified so further investigations are needed.
Treatment of SFCG involves surgical excision of the foreign body and granuloma followed by topical corticosteroids. None of the granulomas recurred at a mean follow-up period of 12 months. In our study, all of the patients underwent surgical excision under surface anesthesia except for one patient who underwent general anesthesia. Surface anesthesia has a number of potential advantages such as minimal bleeding and discomfort. It is currently well established from a variety of studies that if the patient is young, anxious, or non-compliant and the lesion is present for a long period before being recognized or is deeply embedded, general anesthesia is often needed [3,11].
However, this retrospective observational case series has a few inherent limitations. The data were collected over a 4-year period based on the pathologic database, entailing some incomplete specimen data information. Furthermore, the small size of the dataset also meant that it was not possible to demonstrate all-sided features of SFCG. Our preliminary data still needs to be verified and enriched by investigations with more patients.