Whole-transcriptome sequencing identifies postzygotic ATP2A2 mutations in a patient misdiagnosed with herpes zoster, confirming the diagnosis of very late-onset segmental Darier disease

An 82-year-old female patient presented with a recent onset of painful skin lesions in unilateral distribution on the abdominal area following the lines of Blaschko; the initial diagnosis of Varicella-zoster infection was made. However, because the individual lesions appeared as hyperkeratotic papules and were unresponsive to antiviral therapy, a skin biopsy was performed, which revealed hyperkeratosis, suprabasal acantholysis and dyskeratosis with corps ronds and grains, consistent with acantholytic dyskeratotic acanthoma. Since this entity has been associated with Darier disease, whole transcriptome sequencing by RNA-Seq was performed on RNA isolated from a lesion as well as from adjacent normal appearing skin, and a recently developed bioinformatics pipeline that can identify both genomic sequence variants and the presence of any of over 900 viruses was applied. Two pathogenic missense mutations in the ATP2A2 gene were identified in the lesional but not in normal appearing skin, and no evidence of Varicella-Zoster infection was obtained. These findings confirm the diagnosis of segmental Darier disease due to postzygotic mutations in the ATP2A2 gene, and attest to the power of a novel single-step application of RNA-Seq in providing correct diagnosis in this rare genodermatosis.

Type 1 Segmental Darier Disease: Case Report and Discussion of the Treatment Options

Darier disease is a rare type of autosomal dominant genodermatosis, and it is caused by a mutation in the gene coding for the endoplasmic reticulum membrane calcium pump Ca²⁺-ATPase type 2, leading to compromised intercellular adhesion. Moreover, this condition is characterized by multiple keratotic greasy papules with a seborrheic distribution and is worsened by heat and sun exposure, sweating, and friction. Occasionally, it may be associated with nail abnormalities and may involve the mucosa. Unilateral segmental Darier disease is a rare variant characterized by unilateral eruption of erythematic keratotic papules not associated with other conditions. Herein, we report a case of type 1 segmental Darier disease. Furthermore, the main characteristics and treatment options are discussed.