Sir,

IgG4-related orbital disease is an immune-mediated fibro-inflammatory disease with systemic associations1, 2 and predominantly affects middle-aged and elderly patients,2 presentation of IgG4-related orbital disease in children is very rare.3, 4

Case report

A 14-year-old boy presented with an 8-year history of gradually progressive painful protrusion of both eyeballs. Examination showed bilateral massive proptosis with severe fullness of superior sulcus and absent eyelid crease (Figure 1a). All recti were palpably firm and enlarged. Clinical history and examination did not reveal enlargement of salivary glands and there was no evidence of lymphadenopathy or organomegaly. Clinical differential diagnoses included thyroid eye disease/myeloid sarcoma/metastatic neuroblastoma. Systemic examination, complete blood picture, peripheral blood smear, and thyroid function tests were normal. CT scan of orbit in axial and coronal sections showed massive enlargement of the recti in both eyes with involvement of the muscle belly and tendons (Figure 1b).

Figure 1
figure 1

Colour photograph of the patient with bilateral massive proptosis (a). Contrast-enhanced CT scan of the orbits and paranasal sinus in axial section shows grossly proptosed globes with massive enlargement of the belly and tendons of the horizontal recti in both orbits (b). The full colour version of this figure is available at Eye online.

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Microscopic examination of an incisional biopsy from left medial rectus showed fibro-inflammatory tissue (Figure 2a). Fibrous component showed storiform pattern (Figure 2b) adjacent to pattern-less zones. Collagenous tissue was loose to dense with sclerosis and hyalinization. Inflammation was patchy, polymorphic, and ranged from moderate to severe (Figure 2c). They were composed of mature lymphocytes, numerous plasma cells, occasionally with more than one nucleus (Figure 3a) and occasional eosinophils. Granulomatous inflammation or vasculitis was absent. Immunohistochemical stains with IgG4 showed an average of 35–40 IgG4-positive plasma cells per high-power field (h.p.f.) (Figure 3b) counted in three h.p.f.s with maximum plasma cells. Ratio of IgG4-bearing plasma cells and IgG-bearing plasma cells was >40%.

Figure 2
figure 2

Photomicrograph shows fibro-inflammatory tissue (a, haematoxylin–eosin × 100), with characteristic storiform pattern of sclerosis (b, haematoxylin–eosin × 400), and dense polymorphic lymphoplasmacytic infiltrate (c, haematoxylin–eosin × 100).

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Figure 3
figure 3

Photomicrograph shows plasma cell predominance, binucleated plasma cells are arrow marked (a, haematoxylin–eosin × 400), immunoperoxidase staining shows positivity of plasma cells with IgG4, lymphocytes are negative for IgG4 (b, IgG4 × 400).

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Serum IgG4 was elevated at 4.3 g/l (reference range: 0.049–1.985 g/l). A diagnosis of IgG4-related orbital disease was made after excluding systemic involvement on clinico-radiological workup and the patient was started on oral steroids at 0.6 mg/kg body weight. He showed an initial improvement but was subsequently lost to follow-up.

Comment

IgG4-related orbital disease is a previously unreported cause of bilateral proptosis in children.4 Characteristic storiform fibrosis and dense lymphoplasmacytic infiltrate1 call for further immunohistochemical, serological, and systemic evaluation. Commoner inflammatory/infectious causes of bilateral orbital inflammation with systemic associations, such as thyroid ophthalmopathy, granulomatosis with poly-angiitis, sarcoidosis, and tuberculosis, need exclusion. Paucity of literature on IgG4-related orbital disease in children limits protocol-based management; however, glucocorticoids stay as the first-line management strategy with azathioprine, mycophenolate mofetil, methotrexate, or rituximab as the second- or third-line drugs. Long-term close follow-up is warranted to treat relapses and early identification of systemic involvement.