Causes of enlarged corneal nerves

Prominent corneal nerves in pure mucosal neuroma syndrome, a clinical phenotype distinct from multiple endocrine neoplasia type 2B

BACKGROUND

Pure mucosal neuroma syndrome (MNS), an autosomal dominant neurocutaneous disorder, is a rare discrete subgroup in multiple endocrine neoplasia (MEN) type 2B, which present without associated endocrinopathies of MEN2B but with typical physical features such as prominent corneal nerves. Case presentation This report describes a 41-year-old patient with complaint of itchy eyes and irritation, presenting with blocked gland orifices in the upper and lower eyelids, light conjunctival hyperemia, a semitransparent neoplasm measuring 2 mm*2 mm on the nasal limbus suggestive of neuromas, and prominent corneal nerves. In vivo confocal microscopy (IVCM) revealed structural alterations-namely a prominent hyperreflective, thickened nerve plexus and a normal endothelium-in both eyes. Testing for SOS1 mutation was positive. This patient may represent a discrete subgroup termed pure mucosal neuroma syndrome (MNS), which presents with the characteristic appearance of MEN2B but without RET gene mutations.

CONCLUSION

Prominent corneal nerves have been described in some diseases, such as multiple endocrine neoplasia (MEN) type 1 and type 2A and 2B, congenital ichthyosis, Refsum's disease, leprosy, etc. Ophthalmic assessment including prominent corneal nerves has proven valuable in asymptomatic individuals of MEN2B. Our case illustrates the importance of recognizing the ocular features of MNS, a rare presentation of MEN2B, in order to prevent prophylactic thyroidectomy in these patients for prophylactic thyroidectomy is not mandatory in MNS. However, regular monitoring and genetic counseling are still necessary.

A patient with MEN1 typical features and MEN2-like features

Multiple endocrine neoplasia (MEN) type 1 (MEN1) and 2 (MEN2) rarely co-exist in one case. Here we report a patient with features of both syndromes. The patient presented with typical MEN1 features plus pheochromocytoma and thickened corneal nerves. She had a germline 1132delG frameshift mutation in MEN1, no mutation in CDKN1B (p27) and no RET mutation, but had both RET polymorphisms Gly691Ser and Arg982Cys. This is the first case report of a combination of typical clinical findings of MEN1 harboring a germline MEN1 mutation and the MEN2-like phenotype with negative full RET gene analysis of pathogenic variants. Possible explanations include a previously unrecognized phenotype-genotype association or the influence of potential phenotypic modifying RET variants. Furthermore, the combination observed in this patient may point to a single molecular pathway, and supports the possibility of as yet unrecognized connections between the molecular pathways for MEN1/menin protein and MEN2/RET protein.

Dystrophia Helsinglandica: a new type of hereditary corneal recurrent erosions with late subepithelial fibrosis

PURPOSE

To describe the phenotype of an autosomal-dominant corneal dystrophy with an early onset of recurrent corneal erosions and development of subepithelial fibrosis in the cornea, and also to exclude genetic linkage to known corneal dystrophies with autosomal-dominant inheritance and clinical resemblance.

METHODS

We describe the medical history and clinical findings in individuals from a seven-generation family with recurrent corneal erosions. A total of 43 individuals were evaluated by ophthalmological examination. Genomic DNA was prepared from peripheral blood and polymorphic microsatellite markers were analysed to study haplotypes surrounding genes causing corneal dystrophies with similar phenotypes.

RESULTS

Erosive symptoms usually lasted for between 1 and 10 days. By the age of 7 almost all of the affected individuals suffered from recurrent corneal erosions. The attacks generally declined in frequency and intensity from the late 20s, but all examined individuals had developed subepithelial fibrosis by the age of 37. The fibrosis generally started in the mid periphery and was followed in some family members by central fibrosis and the development of gelatinous superficial elevations. Only a marginal reduction of visual acuity was seen in a few individuals. The affected individuals did not share haplotypes for genetic microsatellite markers surrounding genes that are known to cause autosomal-dominant corneal dystrophies.

CONCLUSION

We describe a new type of autosomal-dominant corneal disorder with recurrent corneal erosions and subepithelial fibrosis not significantly affecting visual acuity.