Generalized Cutaneous Lichen Amyloidosis in a Patient with an Ultra-Rare RET Y806C Variant Associated with MEN2A: A Case Report and Literature Review.

Cutaneous lichen amyloidosis (CLA) is a rare dermatological condition characterized by amyloid deposition in the skin, presenting as pruritic, hyperkeratotic papules. Although most cases are sporadic, CLA has been associated with multiple endocrine neoplasia type 2A (MEN2A), a hereditary syndrome caused by germline alterations in the RET proto-oncogene. In MEN2A, CLA is typically localized to the interscapular region and linked to RET codon 634 variants, whereas generalized forms are rare. We report a male patient with MEN2A and a generalized form of CLA that preceded the diagnosis of primary hyperparathyroidism (PHPT) and medullary thyroid carcinoma (MTC). Genetic testing using Sanger sequencing identified an ultra-rare heterozygous RET variant, p.Y806C, in exon 14, currently classified as a variant of uncertain significance (VUS). This variant has not been previously described in association with MEN2A. This case may contribute to understanding genotype-phenotype correlations in MEN2A and suggests that atypical or generalized CLA may be an early clinical clue warranting consideration of RET genetic testing.