Diffuse cutaneous mastocytosis masquerading as linear IgA bullous dermatosis of childhood

Diffuse cutaneous mastocytosis is a rare form of cutaneous mastocytosis that can appear in heterogeneous clinical presentations, including eruption of papules, erythematous plaques, blisters, and erythroderma. We report a 1.5- year-old boy who presented with itchy wheals and blisters spreading on his body. The patient was initially managed as a linear IgA bullous dermatosis of childhood (LABD) because of the similarity of clinical symptoms and the presenting of linear IgA deposits at the basement membrane. Due to the development of urticarial plaque after the resolution of the blisters, the diagnosis of diffuse cutaneous mastocytosis was made based on clinical, histopathological (hematoxylin-eosin, Giemsa, and toluidine blue staining), and direct immunofluorescent examinations (IgA, IgG, IgM, C3). The symptoms were improved following antihistamines and oral corticosteroid treatment.