Phakomatous choristoma of the eyelid: a case with associated eye abnormalities

Phakomatous choristoma is a rare lesion, first reported in 1971¹ with a further 18 cases reported to date. Previously reported cases have not been identified preoperatively, nor associated with ocular abnormalities except as a secondary effect.²,³ We report here a case which was suspected on clinical examination, and which is associated with other eye abnormalities.

Case report

This healthy female patient first presented at the age of 2 days with a red left eye, and she was noted to have a lump in the nasal aspect of the left lower eyelid which was initially diagnosed as a dacryocystocele. The red eye resolved, but the eyelid swelling persisted despite regular massage. There was also concern about left amblyopia, astigmatism, and myopia. On specialist oculoplastic review, the possibility was raised of phakomatous choristoma, and excision with ocular examination under general anaesthetic was carried out at age 10 months.

At surgery, the eyelid mass was removed with no complications. Examination showed a normal right eye, but the left eye showed a colobomatous hypoplastic disc with a staphyloma. Refraction was approximately emmetropic.

Following surgery, the eyelid mass did not recur. However, the patient has developed progressive myopia in both eyes, with left amblyopia. Her most recent refraction at the age of 5 years is −11.25D right eye and −22.0D left eye, and her visual acuity is 6/18 right eye, 3/60 left eye.

Histology of the eyelid mass showed small nests and cords of epithelial cells within a dense fibrous stroma. The cells were bland with pale cytoplasm, and in areas formed vesicle‐like structures containing degenerate swollen cells (fig 1A). Around the nests was a prominent basement membrane (fig 1B), and occasional psammoma‐like bodies were present. The morphological appearance and immunohistochemical staining pattern (cells positive for vimentin and S100, negative for the pancytokeratin AE1/AE3) were typical of phakomatous choristoma (fig 2A and B).

Figure 1 (A) Vesicle‐like structures are present with thick basement membrane‐like material and a swollen cell (haematoxylin and eosin ×20). (B) The basement membrane surrounding the epithelial islands is accentuated (DPAS ×10).

Figure 2 (A) S100 immunoreactivity is restricted to epithelial cells (S100 ×10). (B) The epithelial cells are strongly positive for vimentin (Vimentin ×10). There is also vimentin positivity in stromal cells.

Comment

Phakomatous choristoma is a lesion first described over 30 years ago. It is viewed as a proliferation of ectopic lens tissue, which presents at a young age and may enlarge because the abnormal cells are attempting to proliferate and differentiate. The clinical presentation is with a mass located at the nasal aspect of the medial eyelid and/or orbit. The histological appearance is of lens‐type epithelium, with degenerate areas reminiscent of the Wedl or “bladder‐like” cells of cataract. Previously reported cases have shown immunohistochemical and ultrastructural appearances consistent with a lenticular origin.³,⁴,⁵,⁶,⁷

Theories of pathogenesis include (1) surface ectoderm “dipping down” into the mesoderm of the developing eyelid, (2) migration of putative lens tissue through the closing optic fissure, and (3) the site of origin of the invaginating lens being located in the area destined to form the nasal lower lid.¹,⁵,⁸,⁹,¹⁰

None of the previously reported cases has had any other ocular or orbital abnormalities, apart from astigmatism or epiphora attributable to the eyelid lesion that resolved postoperatively. The patient we report here also has a colobomatous hypoplastic optic disc with staphyloma, and severe myopia. Although the eye abnormalities here may be coincidental, the presence of a left optic disc coloboma and staphyloma suggests that there may have been an abnormality of closure of the optic fissure.