Sir,

Langerhans cell histiocytosis (LCH) occurs mainly in childhood but is rarer in adults (1–2 per million).1 Many organs can be involved, most frequently bone, including orbit. We report a rare adult case of LCH, with unusual ocular skin presentation and uveal tract involvement.

Case report

A 45-year-old man had a right medial canthal nodule for 5 weeks. He smoked and drank to excess. His right VA was 6/9, left VA was 6/12. Excision biopsy of the lesion showed a dermal cellular infiltrate composed of histiocytic cells and eosinophils. The histiocytes displayed irregular, cleaved nuclei and demonstrated strong immunoreactivity for CD68, S100, and CD1a (Figure 1). Necrobiosis or giant cells were not present and there was no infiltration of epidermis. This pattern and immunocytochemical profile excluded the main differential diagnoses of Hodgkin's and non-Hodgkin's lymphoma, mycosis fungoides, and inflammatory disorders such as xanthogranuloma. The CD1a-positivity confirmed Langerhans cell histiocytosis. He failed to attend for follow-up. Fifteen months later, he developed black visual field shadows. VAs were 6/12 bilaterally, 6/9 on pinhole correction. Fundoscopy revealed bilateral posterior uveitis, vitritis, and retinal vasculitis, and a left chorioretinal lesion (Figure 2). Vasculitic and infective screens (autoantibodies including ANF, ANCA, rheumatoid factor, and blood and CSF infective screen) were negative. Chest radiology was normal. He was treated with 60 mg prednisolone/day. Three weeks later, he developed a maculopapular rash involving face, neck, and hands. Skin biopsy showed LCH.

Figure 1
figure 1

(a) Skin biopsy, showing infiltration of the dermis by S100-positive and CD1a-positive Langerhans cells.

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Figure 2
figure 2

(a, b) Right and left fundi, showing a hazy view because of vitritis: there is vasculitis bilaterally and a left chorioretinal lesion (arrow). (a) Right fundus, (b) Left fundus.

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His vision deteriorated (right VA 6/36, left VA 6/24) owing to bilateral anterior and posterior uveitis. Fundoscopy showed diffuse vasculitis, retinal haemorrhages, retinal oedema, and vitreous opacities, interpreted as uveitis masquerade syndrome. Repeat vasculitic screen was negative. CT of thorax, abdomen and pelvis was normal. Bone marrow aspirate and biopsy were negative for LCH or other co-existing malignancy.

He developed gait ataxia and distal hyperpathia. MRI brain showed increased signal intensity in both basal ganglia (Figure 3a) and medial recti. Meninges, cerebellum, and brainstem appeared normal.

Figure 3
figure 3

(a) MRI of brain with abnormal signal intensity in the basal ganglia. (b) CSF cytology showing Langerhans cells and eosinophils.

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Cerebrospinal fluid (CSF) examination showed LCH cells (Figure 3b). In view of the positive CSF, a vitreous aspirate was not performed. He received cranial radiation and intravenous and intrathecal chemotherapy. Vision improved (VA 6/9 bilaterally); speech and gait remained impaired. Repeat CSF examinations were negative for LCH cells. Two years later, bony lesions have not occurred.

Comment

Ocular presentation of adult LCH is exceptional. A solitary eyelid lesion,2 solitary choroidal LCH,3 a limbal nodule4 and six chorioretinal LCH cases5, 6 are reported. To our knowledge, this is the first report of LCH causing uveitis masquerade syndrome. Only 1–4% of LCH patients develop intracerebral infiltration not extending from bone, usually with widespread disease and 5 years after diagnosis.7 Only 7 cases of positive CSF are reported,8 usually with meningeal infiltration. CSF involvement in this patient probably reflects brain infiltration, since meninges were normal on imaging. This case demonstrates unusual manifestations of LCH in the adult eye.