Sir,

Myeloid sarcoma (MS) is an extramedullary tumour of immature myeloblasts associated with leukaemias.1 MS commonly presents after diagnosis of active leukaemia, during a recurrence, or as a blastic transformation of myelodysplastic syndrome. Rarely, MS arises de novo.2, 3 Here, we describe a case of MS presenting de novo with a white anterior chamber infiltrate.

Case report

A 3-month-old infant presented to an outside ophthalmologist with a unilateral ‘discoloured iris.’ He was referred for retinoblastoma vs endophthalmitis. Examination showed a fluffy, white anterior chamber infiltrate and scarce vitreous cell in the right eye. The rest of the ocular exam and peripheral blood studies were unremarkable.

Social reasons delayed the exam under anaesthesia and MRI for 12 days. Unexpectedly, he developed bilateral proptosis, lacrimal gland swelling, a larger right anterior chamber infiltrate, and new left anterior chamber infiltrate (Figure 1). MRI of the brain showed infiltrative bone marrow processes with involvement of bilateral globes, lacrimal glands, extraocular muscles, and paranasal sinuses (Figure 2).

Figure 1
figure 1

Presentation at first exam under anaesthesia showing bilateral proptosis, lacrimal gland swelling, and bilateral anterior chamber infiltrates.

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Figure 2
figure 2

MRI demonstrates prominent lacrimal gland swelling.

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Lacrimal gland biopsy revealed MS. The H&E stain showed sheets of tumour cells and the lysozyme stain was positive (Figures 3a and b). Work-up of blood and bone marrow showed no evidence of malignancy.

Figure 3
figure 3

(a) H&E reveals sheets of tumour cells with a high mitotic rate. (b) Lysozyme staining is positive. Photos courtesy of Dr. Hans Grossniklaus.

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After two courses of 10-day cycles of cytarabine, daunorubicin, and etoposide, CNS involvement was seen and additional intrathecal therapy was started. His lesions regressed and anterior segment infiltrates disappeared (Figure 4).

Figure 4
figure 4

Significant resolution of infiltrates and proptosis after two cycles of chemotherapy.

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Before his fifth course, rare leukaemic blasts were noted in the CSF. These cleared with intrathecal therapy; however, during recovery, leptomeningeal enhancing lesions were noted. He was started on palliative oral VP-16 (etoposide). After multiple relapses despite external radiation and chemotherapy, the decision was made to start palliative whole brain radiation. He passed away 4 months later.

Comment

MS is rare and often misdiagnosed.2, 3 The incidence of a single MS is 2% in AML,1 whereas orbital MS accounts for 1 of 250 cases.4 An anterior chamber infiltrate might be misdiagnosed as retinoblastoma or hypopyon, resulting in delayed or improper treatment. We present this case to emphasize that MS should be considered in patients with white anterior chamber infiltrates even if previously healthy.