{'fraction_non_alphanumeric': 0.021809369951534735, 'fraction_numerical': 0.0035002692514808833, 'mean_word_length': 5.506129597197899, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Rare case of Langerhans cell histiocytosis of the conjunctiva

Langerhans cells are specific antigen presenting cells normally found in the basal layer of the epidermis, squamous epithelia, hair follicles and apocrine/sebaceous glands. Langerhans cell histiocytosis (LCH) is a rare condition characterized by neoplastic proliferation of Langerhans cells and usually affects men and children. Langerhans cell histiocytosis lesions are usually unifocal and typically involve the skull, pelvis and femur. Ocular or orbital involvement is very rare. We present a case of rare ocular LCH in a 22-year-old male with conjunctival Langerhans cell histiocytosis. The patient initially presented with a year-long history of temporal injection and irritation of the right eye. He reported no visual deterioration and had previously tried multiple types of eye lubricants without any improvement in symptoms. The patient had recently immigrated to Australia from Afghanistan and reported no other ophthalmic history, medical history or surgical history. He took no regular medications and had no allergies. He reported feeling otherwise well with no other systemic symptoms. On initial examination, visual acuity was 6/5 in both eyes with normal intraocular pressures and no sign of proptosis. Anterior segment examination showed injected temporal conjunctiva and sclera in the right eye. There was no blanching of the injection with 10% topical phenylephrine and no associated fluorescein uptake. Otherwise the eyes were quiet, with clear corneas and no sign of intraocular inflammation. Posterior segment examination was unremarkable bilaterally. The patient was initially treated with topical corticosteroids and oral ibuprofen with a working diagnosis of early nodular non-necrotizing scleritis. Extensive blood testing involving full blood count, electrolytes, liver function tests, inflammatory markers, rheumatoid factor, ANA, C-ANCA/P-ANCA, syphilis, QuantiFERON Gold (Cellestis, Ltd. Carnegie, Australia) and ACE were all normal. Chest X-ray was also normal. Over the next month, the patient’s irritation and right eye injection only settled slightly. Further examination revealed a raised 3 mm diameter fibrovascular mass with feeder vessels within the now reduced right temporal injection (Fig. 1). The mass appeared to be within the conjunctiva with no evidence of any deeper invasion. Excisional biopsy was recommended and undertaken 3 weeks later. The conjunctival lesion was easily excised with adequate macroscopic margins, and cryotherapy was applied to the edges of the conjunctival defect. Histopathology showed aggregates of Langerhans cells with a surrounding infiltrate of eosinophils and lymphocytes. Immunohistochemistry confirmed positive staining for CD1a and S100. Features were consistent with conjunctival LCH. Margins of the specimen were clear. The patient’s eye settled postoperatively with no further irritation or injection and was subsequently referred to haematology. A detailed systemic examination including Computed Tomography (CT) head, chest, abdomen and pelvis, positron emission tomography scan, magnetic resonance imaging head and bone marrow aspirate and trephine showed no evidence of systemic LCH, and a final diagnosis of unifocal conjunctival LCH was made. Conjunctival LCH has only been reported six times previously, three times at the conjunctival limbus, twice at the caruncle and once on the epibulbar conjunctiva. Although this is a very rare condition, LCH should be recognized as a possible malignant cause of a conjunctival lesion with potentially serious systemic manifestations, and thus should be considered in the differential diagnosis of any conjunctival lesion.