Can you diagnose this condition?

A 7 year-old male comes to your clinic with a large blister on his left foot. They come and disappear after a few days. Occasionally, he also develops swollen lips, swollen tongue, colicky abdominal pain with these blisters. Blisters are not itchy but slightly painful. These episodes come every few months and last for 1-2 days. Patient reports that one of his uncles has a similar disorder. Laboratory tests revealed low C4 complement level and low C1 esterase inhibitor level. What is the most likely diagnosis in this patient? 

A.Allergic dermatitis 

B.Hereditary angioedema 

C.Pemphigus vulgaris 

D.Dermatitis herpetiformis 

Correct answer B. Even though blisters are uncommon in hereditary angioedema, this patient’s symptoms, family history and laboratory results are consistent with hereditary angioedema. Allergic dermatitis, pemphigus vulgaris, dermatitis herpetiformis are not consistent with this patient’s clinical profile.