Sir,

Neurofibromatosis Type 1 (NF1) is an autosomal dominant disorder that commonly presents with ophthalmic lesions.1 We would like to present a case of a patient with previously undiagnosed NF1 presenting with upper eyelid plexiform neurofibroma masquerading as a persistent chalazion. To our knowledge, this is the first such case to be reported.

Case report

A 7-year-old Filipino boy was referred to the eye department with a 1-year history of swelling and a lump at the lateral end of the right upper eyelid. On examination, initial impressions were of two palpable nodules of which the appearances were found to be consistent with a diagnosis of chalazion. He had incision and curettage of the lesions under general anaesthesia 4 months later. No samples were sent for histology and he was discharged. However, he re-presented 1 year later with persistent chalazion. On examination, there was persistent swelling of the right upper eyelid (Figure 1a) with two mobile firm lumps underneath the skin extending from the lid to the lateral orbital rim. An excisional biopsy under general anaesthesia was carried out. Intraoperatively, the diagnosis of plexiform neurofibroma was suspected and later was confirmed on histology. A general physical examination revealed café au lait spots (Figure 1b) and Lisch nodules. These with the presence of plexiform neurofibroma fulfilled the criteria for the diagnosis of NF1. There was no family history of this condition.

Figure 1
figure 1

(a) Right upper eyelid swelling, (b) café au lait spots.

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Comment

NF1 is categorized as a neurocristopathy (ie, a disorder that primarily affects tissues derived from the neural crest) and has a birth incidence of between 1 in 2500 and 1 in 3000 and a prevalence of 1 in 5000. The complete list of criteria for the diagnosis of NF1 is summarized in Table 1.

Table 1 Criteria for diagnosis of NF1: fulfilling at least two of seven criteria makes a diagnosis of NF1
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Plexiform neurofibroma is pathognomonic of NF1, and often appears within the first 2 years of life followed by cutaneous neurofibromas. Pathologically, a plexiform neurofibroma represents diffuse involvement of a long nerve segment and its branches with tortuous expansion, and its gross appearance has been described as a ‘bag of worms’. This lesion frequently involves the trigeminal or upper cervical nerves and occurs less commonly in eyelids compared to the trunk area. Plexiform neurofibroma occurs in only 10% of patients with NF1.2 Plexiform neurofibromas need to be monitored frequently because 5 % develop into malignant peripheral nerve sheath tumours. The most serious problem is the development of glaucoma in the eye ipsilateral to the plexiform neurofibroma. This develops in upto 50% of patients.2

In conclusion, a recent report stated that a number of different benign, premalignant, and malignant conditions may clinically masquerade as a chalazion.3 Hence, we would like to emphasize the importance of histological sampling when there is recurrent or persistent chalazion. Plexiform neurofibroma needs to be borne in mind as a possible differential diagnosis of a chronic orbital or lid swelling. This case illustrates the importance of general physical examination, even in a busy eye clinic. In this case, considerable delays in establishing diagnosis could have been avoided.