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Pencil injury can lead to ocular graphite foreign body
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Graphite is a substance made of carbon, and ocular trauma in a younger age group has been known to happen with graphite lead in pencils. Pencil injury has been documented to produce an ocular foreign body when the broken lead is lodged in the eye.
Pencil lead is made of graphite and clay with some additional substances, such as spindle oil, liquid paraffin and silica. Pigmentation from the pencil lead can give a dark appearance and therefore mimic a neoplasm. The extraocular graphite foreign body due to a pencil injury can present with late granulomatous reaction mimicking melanoma. Aniline dye has been known to induce inflammation, while graphite lead has been known to remain indolent. Honda and colleagues reported intraocular graphite lead 6 years after injury. In this column, we present a case with a chronically existing conjunctival graphite lead mass with a recent increase in size without clinical signs of inflammation.
Pencil injury and presentation
A young female patient was seen in the outpatient department with a history of a pigmented mass in her right eye. There was a remote history of injury with a sharp pencil while playing about 10 years prior. The patient confirmed the presence of the pigmented mass for the last 10 years and noticed a sudden increase in size over the past month. There was no associated pain, irritation, watering or redness.
On clinical examination, there was a subconjunctival non-tender pigmented mass about 4 mm by 3 mm in the nasal region (Figure 1). The overlying conjunctival vessels were clearly visible. The mass had a slight glistening appearance and was firmly adherent to the underlying Tenon’s layer. We performed anterior segment optical coherence tomography (Visante, Carl Zeiss Meditec) on the lesion and noticed that the mass showed back shadowing of 4 mm (Figure 2). The patient’s best corrected visual acuity was 20/20 in both eyes, and her IOP was normal. Fundus examination showed a normal disc and macula.
Figure 1. Subconjunctival graphite lead.
Images: Agarwal A, Kumar DA
Figure 2. Back shadowing seen on the region of the subconjunctival mass on OCT.
Figure 3. H&E staining on 40X magnification showing the multinucleated graphite laden giant cells (arrow).
Our provisional diagnosis was conjunctival retained graphite lead and acute-onset granuloma. Subsequently, the conjunctival mass was removed and histopathology was performed. Intraoperatively, the pigmented mass was noted to be adherent to the surrounding Tenon’s layer, and a few black deposits were dispersed. Thorough saline wash of the surrounding area was performed after removal of the particles. The conjunctiva was closed with 6-0 Vicryl sutures.
The postoperative period was uneventful. On H&E staining, there was thin fibrous tissue enclosing a collection of foreign bodies (seen as black particles) (Figure 3). Numerous foreign body types of giant cells with peripheral lymphoid collection and histiocytes were seen infiltrating the intervening thin fibrous tissue. A large mass of graphite lead was also seen surrounded by collections of graphite lead laden giant cells (Figure 3).
Imaging of foreign body
OCT has been utilized to document conjunctival pigmented tumors, which are seen as homogeneous solid masses, and OCT shadowing has been noted to vary depending upon the amount or intensity of pigmentation. It has also been used to locate and measure ocular surface foreign bodies. In our case, we noted total shadowing in the region of the mass in the OCT and no transmittance of coherent light through the subconjunctival lesion. In OCT, the restriction of light penetration due to dense carbon results in posterior shadowing and difficulties in delineating the posterior edge of the lesion.
Ultrasound imaging can be done in such lesions with a water immersion technique. Moreover, high-resolution ultrasound biomicroscopy (UBM) would be more useful in localizing the posterior limit of such lesions and documenting the acoustic pattern. CT has been used for evaluating intraorbital graphite foreign bodies. Retained graphite lead can be a differential diagnosis for conjunctival pigmented mass, and this can be differentiated by OCT or UBM. However, in anterior segment foreign bodies, OCT is equally useful without the risk of radiation exposure. Faster acquisition, high resolution (18 µm) and non-contact nature have made it easily applicable for frequent examination or follow-up examination, especially in eyes in which progression is suspected. Nevertheless, histopathological evaluation is always confirmatory in such situations.
Graphite lead granuloma
Graphite is entirely made of carbon and is the most stable form of carbon under standard conditions. The sharp tip of the pencil is usually the culprit in this type of injury. Graphite foreign bodies usually maintain their uniform size for a long duration because they are not removed by histiocytes. Graphite lead can induce granulomatous reaction as late as 17 years, as reported by Guy and colleagues. Hence, removal of the extraocular graphite lead is recommended in these eyes. Proper awareness and education of possible ocular trauma with a pencil should be developed to prevent such injuries in a younger age group.