Cutaneous mosaicism: Special considerations for women

Abstract

Genetic mosaicism results from postzygotic mutations during embryogenesis. Cells harboring pathogenic mutations distribute throughout the developing embryo and can cause clinical disease in the tissues they populate. Cutaneous mosaicism is readily visualized since affected tissue often follows predetermined patterns, such as lines of Blaschko. Due to its clinical accessibility, cutaneous mosaicism is well suited for genetic analysis. An individual's unaffected tissue can be used as an intrapatient genetic control, a technique that has yielded insight into the genetic etiologies of many disorders, several of which bear mutations in genes that would otherwise be embryonic-lethal. Particular mosaic diseases can also disproportionally impact women. Two such diseases, incontinentia pigmenti (IP) and congenital hemidysplasia with ichthyosiform erythroderma and limb defects (CHILD) syndrome, arise from mutations on the X chromosome. Both diseases result in fetal demise in males in most cases, thus making the two diseases largely specific to women. Women with McCune–Albright Syndrome, caused by somatic mutations in GNAS , often experience precocious puberty and infertility as a result of uncontrolled cAMP regulation in affected tissue. Women with cutaneous mosaicism carry a risk of transmission to offspring when gonosomal mosaicism is present, yet cutaneous disease burden does not correlate with germline transmission risk. Cutaneous mosaic disease represents a biologically unique set of disorders that can warrant special clinical attention in women.

Unilateral Blaschkoid‐linear verrucous lichen planus under immunotherapy with pembrolizumab

“…So far, there exists only one report on Blaschkoid-linear LP under anti-PD-1 treatment in a patient with renal cell carcinoma who also showed bullous skin lesions. 5 In the present case, lichen striatus and adult-onset inflammatory linear verrucous epidermal naevus have firstly been considered but lastly excluded as clinical differential diagnoses. 6,7 In conclusion, clinicians should be aware that Blaschkoidlinear lichenoid reactions have to be included in the spectrum of anti-PD-1 treatment-induced inflammatory cutaneous adverse events in patients with cancer.…”