Unilateral Blaschko-linear eruption with Gottron-like papules: blaschkoid lupus erythematosus or dermatomyositis?

A 6-year-old boy presented with dusky erythematous plaques in linear and whorled pattern over limbs and trunk for the past 1 year along with subcutaneous nodule on the left cheek of 3 months duration. He also had Gottron-like and inverse Gottron-like papules on hands. Histology from truncal lesion showed interface dermatitis with superficial and deep perivascular and periappendageal infiltrate suggestive of discoid cutaneous lupus erythematosus (CLE), while biopsy from facial nodule revealed features of lupus panniculitis. The connective tissue disease workup showed only antinuclear antibody positivity (2+, 1:100 dilution). There was no clinical or investigational evidence of myositis as part of dermatomyositis (DM) workup. A final diagnosis of Blaschko-linear CLE was made, since Gottron-like and inverse Gottron-like papules can be found in CLE as well. The present case highlights the rarity of presentation of CLE along Blaschko lines and overlapping features of Blaschko-linear CLE with DM.