Sir, frontal bone. It has also been described in the lateral Single-site Langerhans cell (eosinophilic orbital wall and sphenOid bone. granuloma) of the orbit Single-site Langerhans cell histiocytosis (eosinophilic Case report granuloma) of the orbit is a rare tumour caused by a A 2-year-old boy presented with a 6 week history of proliferation of Langerhans cells. These antigen­ swelling of the left upper lid. Treatment with systemic presenting cells are part of the mononuclear phagocyte antibiotics had failed to halt the slow growth of this system and are normally found in the conjunctiva, the swelling. Clinical examination revealed a firm, rubbery epithelium of the peripheral cornea and at the limbus as lesion in the supero-nasal orbit (Fig. 1A). The left upper well as in the epidermis, lymph nodes, and thymus. lid showed an erythematous discolouration. The left eye Langerhans cell histiocytosis (LCH) is a disturbance in had a slight deviation outwards and downwards. Visual immunoregulation resulting in proliferation of acuity was normal in both eyes. Langerhans cells and forms one type in a spectrum of CT and MRI scanning confirmed the presence of a histiocytic disorders which are still in the process of mass in the superior orbit, extending through the orbital 1 2 being classified. • Expanding, erosive accumulations of roof into the anterior fossa (Fig. 18). Intracranially, the these cells, admixed with eosinophils, lymphocytes, tumour had not spread laterally from the rim of the plasma cells and neutrophils, form granulomata within osteolytic defect. Orbital biopsy led to the diagnosis of the medullary cavities of bones such as femur and ribs, in LCH (Fig. 1C). Investigations for the infiltration of bone skull bones, and also in skin, lungs and stomach. The marrow, lung, skin and liver were negative. After eosinophilic component can range from a few cells to consultation with teams in paediatric neurosurgery, sheet-like masses of cells. plastic surgery and paediatric oncology, it was decided Single-site LCH of the orbit is a solitary, localised to treat the patient with a single dose of intravenous 2 form of LCH, which most commonly originates in the (6 mg/m ) and a course of systemic

Fig. 1. (A) Clinical photograph at presentation. (B) Unenhanced and gadolinium-enhanced coronal MRI scan showing tumour in the left superior orbit, eroding through orbital roof into the anterior cranial fossa. (C) Histology of the tumour. (a) Haematoxylin & eosin stain. Langerhans cells (arrows) have large, pale nucleus and rim of cytoplasm. Original magnification x400. (b) Immunocytochemical stain for CD-la. Langerhans cells show uptake of stain. Original magnification X400. (c) Electron microscopic appearance of Birbeck granule. Note the pentalaminar structure and racquet-like appearance. Magnification x 135 000. (D) Clinical photograph 2 months after treatment. The scar is from the orbital biopsy.

109 prednisolone (40 mg/m2 per day daily for 28 days, This case illustrates the importance of a multi­ reduced to zero over the next 2 weeks). This induced a disciplinary approach to the individual patient in order dramatic reduction in tumour size and re-established to achieve the best possible functional and cosmetic normal extraocular movements (Fig. lD). A MRI scan 2 outcome. months after treatment was normal. As LCH is a relapsing remitting condition, the patient remains under References

periodic review. 1. Webb DK. disorders. Br Med Bull 1996;52:818-25. 2. Favara BE, Feller AC, Pauli M, et al. Contemporary classification of histiocytic disorders. The WHO Committee on Comment histiocytic/ reticulum cell proliferations. Med Pediatr Oncol 1997;29:157-66. Single-site LCH of the orbit presents clinically with a 3. Moore AT, Pritchard J, Taylor DSl. Histiocytosis X: an short history of erythema of the eyelids, a soft palpable ophthalmological review. Br J OphthalmoI1985;69:7-14. anterior orbital mass and, depending on tumour size and 4. Feldman RB, Moore DM, Hood CI, Hiles DA, Romano PE. Solitary of the lateral orbital wall. location, proptosis. On plain radiographs it appears as an Am J Ophthalmol 1985;10:318-23. osteolytic lesion with irregular margins, and on CT and 5. Jakobiec FA, Trokel SL, Aron-Rosa D, Iwamoto T, Doyon D. MRI as a soft tissue mass with bony destruction. It is Localized eosinophilic granuloma (Langerhans cell isodense or hyperdense with regard to brain and histiocytosis) of the orbital frontal bone. Arch Ophthalmol 1980;98:1814-20. enhances homogeneously with intravenous contrast 6. Wirtschafter JD, Nesbit M, Anderson P, McClain K. media. Intralesional methylprednisolone for Langerhans cell Histopathologically, Langerhans cells are histiocytosis of the orbit and cranium. J Pediatr Ophthalmol characterised by abundant cytoplasm, oval or indented Strabismus 1987;24:194-7. nucleus, and pentalaminar cytoplasmic structures called 7. Kramer TR, Noecker RJ, Miller JM, Clark LC. Langerhans cell histiocytosis with orbital involvement. Am J Ophthalmol Birbeck granules which can be identified on electron 1997;124:814-24. microscopy. These granules are discoid in their three­ 8. Chazi I, Phillippe J, Portas M, Bergue A, Patte C, Bonsch M. dimensional form but appear rod-like in section. Their Solitary eosinophilic granuloma of the external wall of the profile occasionally has can expanded end, giving them a orbit. J Fr OphtalmoI1991;14:189-94. racquet-like appearance. Their function is unclear. As 9. Rawlings CE 3rd, Wilkins RH. Solitary eosinophilic granuloma of the skull. Neurosurgery 1984;15:155-61. Langerhans cells express specific antigens such as SIOO and CD-la, immunohistochemical stains are used to Annegret H. Dahlmann 1 confirm the diagnosis. Ian Simmons 1 Sue Picton4 Due to the low incidence of this disease treatment Andrew Cassels-Brown 1 protocols differ. One case of spontaneous resolution has Leslie Bridges2 been reported? Incisional biopsy and curettage was Michael Nelson3 curative in 2 cases,4 as was excision, complemented by Robert M.L. Doran 1 1 low-dose radiotherapy in 4 patients.s Intralesional Department of Ophthalmology 6 2Department of Neuro-Pathology methylprednisolone led to resolution in 1 case, and 3Department of Neuro-Radiology intravenous vincristine and prednisolone have been used Leeds General Infirmary Leeds, UK successfully in 3 cases with multifocal lesions? 4St James's University Hospital Treatment by vinblastine and steroids has been reported Yorkshire Regional Centre for Paediatric Oncology & Haematology Leeds, UK. in 1 patient.s However, in all these studies follow-up was limited. Mr R.M.L. Doran, FRCOphth, FRCSEd � Usually, the prognosis is reported to be excellent, but the Department of Ophthalmology Leeds General Infirmary only study with long-term follow-up (average 8 years) Clarendon Wing reported that 8 of 26 patients (31%) treated with excision Belmont Grove with or without local, moderate-dose radiation therapy Leeds LS2 9NS, UK

developed additional lesions over the following 1 month Tel: +44 (0)113 243 2799 9 to 25 years. Fax: +44 (0) 113 392 6239 In the case presented, radiotherapy was not acceptable due to the patient's young age and the long­ term side-effects of radiotherapy. Surgical removal Sir, would have required a craniotomy approach, and due to Ganciclovir implant: clinicopathological study orbicularis oculi muscle involvement would have Cytomegalovirus (CMV) retinitis has been the leading resulted in a poor cosmetic result with ptosis. cause of visual disability in patients with the acquired Intralesional methylprednisolone was not practicable syndrome (AIDS). It affects due to the size of the mass and its extension into the approximately one-third of such patients. 1 Ganciclovir anterior fossa. Chemotherapy with vinblastine and and foscarnet are the conventional drugs used for the steroids, on the other hand, offered quick resolution with treatment of CMV retinitis. When administered minimal risk of side-effects. systemically these drugs are known to cause serious side-

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