Somatic Mosaicism for a "Lethal" GJB2 Mutation Results in a Patterned Form of Spiny Hyperkeratosis without Eccrine Involvement.

BACKGROUND: Spiny hyperkeratosis refers to a rare clinical phenotype characterized by nonfollicular keratotic projections and sometimes associated with other acquired and inherited conditions. We describe a case of congenital patterned spiny hyperkeratosis. METHODS: To identify the cause of this disorder, we used a combination of whole exome sequencing, direct sequencing and TaqMan assay. RESULTS: We found that the peculiar clinical features displayed by the patient are due to somatic mosaicism for a heterozygous mutation in the GJB2 gene. CONCLUSION: Because histopathologic examination of two independent biopsies did not reveal porokeratotic eccrine ostial and dermal duct nevus (PEODDN), previously reported to result from somatic mutations in GJB2, it appears that mutations in this gene can cause nevoid spiny hyperkeratosis in the context of PEODDN or as an isolated finding.

Unilateral spiny hyperkeratosis: case report and review of the literature.

We describe the first case of unilateral spiny hyperkeratosis (SH) of the left hand, review the literature and discuss possible patho- mechanisms. SH can be sporadic or familial, often appearing in healthy individuals. However, there is an association with various malignancies in a significant number of the sporadic cases. Although there is no satisfactory explanation of this association, we agree with previous authors that a patient with SH appearing in adult life should be evaluated and followed for the presence of malignancy. Other patients with SH may suffer from a variety of nonmalignant diseases, which may be coincidental or causally related. SH is not a premalignant lesion of the skin and should not be confused with porokeratosis which has a malignant potential. Except for excision of individual lesions, there is no permanent cure.