A patient with subacute cutaneous lupus erythematosus along Blaschko lines: Implications for the role of keratinocytes in lupus erythematosus

Blaschko lines are manifestations of cutaneous mosaicism, with apparent contrast between normal cells and abnormal cells, which carry postzygotic mutations. Linear cutaneous lupus erythematosus is a rare subset of cutaneous lupus erythematosus (CLE), characterized by skin lesions along Blaschko lines. In this paper, we presented a 47-year-old female with subacute CLE lesions along Blaschko lines. Although the antinuclear antibody and anti-Ro titers were remarkably high, there were no systemic symptoms. The histopathology showed atrophic epidermis with vacuolization of basal keratinocytes and papillary edema. While no typical linear lupus band was found, the direct immunofluorescence revealed cytoid bodies with immunoglobulin G, immunoglobulin M, C3, and C4 depositions in the papillary dermis. The skin lesions completely resolved after topical tacrolimus treatment, and the clinical course was 10 months without recurrence. We reviewed the literature and summarized that CLE along Blaschko lines supports the functional role of Ro antigens and keratinocytes in the development of CLE.