Familial pyoderma gangrenosum in association with common variable immunodeficiency

Funding sources: none. Conflicts of interest: none declared. Dear Editor, Pyoderma gangrenosum (PG) is a rare skin disease characterized by noninfective, painful, necrotizing ulcerations. PG is extremely rare in the paediatric population; 4% of patients are infants and children.1 The occurrence of PG in a familial pattern is extremely rare. As far as we could ascertain, only three reports of familial predisposition in PG have been published previously in the English literature.2 3 4 The aetiopathogenesis of PG is still unclear. Its association with a variety of immunological disorders suggests an underlying defective immune system.5 6 However, to date, no cases of PG have been described in the context of common variable immunodeficiency (CVID). We report familial PG in two siblings with CVID, which we believe to be the first documentation of this kind. Patient 1, a 9‐year‐old boy born to nonconsanguineous parents, presented with painful ulcers that had appeared 2 months before. He had a history of recurrent episodes of lower respiratory tract infection since the age of 3 years leading to bronchiectasis. On clinical examination, the child was febrile, underweight and had multiple ulcers with undermined, violaceous margins and indurated bases on his neck, scalp, upper and lower extremities, groin and buttocks. The oral mucosa was particularly affected, presenting pustular exophytic lesions with an erythematous halo and friable membrane that easily disintegrated leading to exulcerated and vegetating lesions of the labial mucosa (Fig. 1). The rest of the clinical examination was unremarkable. Laboratory investigations revealed an elevated level of inflammatory markers. Cultures for bacteria and fungi from skin lesions and blood were repeatedly negative. A skin biopsy specimen revealed an ulcerated epidermis with a massive neutrophilic infiltrate in the upper and lower dermis. Based on the clinical and histological features, the diagnosis of PG was made and the patient was treated with oral prednisone 1 mg kg−1 daily, which induced a great improvement in his lesions and complete resolution in 4 weeks. The steroids were slowly tapered with no recurrence 1 year after the diagnosis. CVID was diagnosed when screening investigations revealed low IgG and IgM levels (IgG 5 g L−1, normal range 6·13–15·12; IgM 0·4 g L−1, normal range 0·7–2·84), absent response to polysaccharide and protein antigens, a reverse CD4:CD8 ratio, with normal complement levels and nitroblue tetrazolium test functional assays. The percentage of total B cells was within the lower normal range (5% of circulating lymphocytes) but with a reduced number of memory B cells identified by the surface marker CD27 (2% of B cells, normal range 6·5–29·2%).