KEY WORDS: bullous pemphigoid; ulcerative colitis.Bullous pemphigoid (BP) is an uncommon blistering skin disease, mainly affecting the elderly and often described in association with other autoimmune disorders (1-5). It has rarely been reported in association with IBD (2, 6-8). We report two patients with ulcerative colitis (UC) who developed BP at an age younger than that of the typical BP patient. Given the rarity of BP and the immune dysregulation common to both UC and BP, namely, a Th2 antibody response, we postulate a casual association of these disorders. Furthermore, BP could be considered an extraintestinal manifestation of IBD. CASE REPORTSPatient 1. This patient was originally from Iran but has lived in the United States for 11 years. He was diagnosed with leftsided UC at age 38. Immune modulators were required to control his bowel disease, but since he developed an adverse reaction to azathioprine, he was maintained on oral and topical 5-ASA medications. While on this regimen he reported 3-4 stools/day and occasional blood, muscus, and tenesmus.At age 41 he complained of pruritus of the knees and fragility of the skin on the dorsum of his hands. Physical exam revealed lichenified plaques containing small tense vesicles. Marked fragility of the skin and onycholysis were also noted. Mucous membrane involvement was absent.Direct IF of a punch skin biopsy revealed a thin linear IgG deposition in the basement membrane zone (BMZ) Figure 1). Indirect IF of salt-split skin showed circulating IgG anti-BMZ antibodies binding to the epidermal side of the specimen, confirming the diagnosis of BP.Topical high-potency steroids did not control his symptoms. Mycophenolate mofetil (MMF) was started at 2 g/day, with improvement of both skin and bowel symptoms. After several Manuscript . months, the MMF was increased to 3 g/day for better control of oncycholysis.Patient 2. This patient presented with UC pancolitis at age 22 and was diagnosed with primary sclerosing cholangitis (PSC) at age 40.The patient had a long history of dermatologic symptoms. At age 11 he was treated for a blistering skin rash of unknown etiology. At age 22 he was diagnosed with a transient vesiculo-erosive stomatitis. At age 43 he complained of blisters on his legs and was diagnosed with folliculitis and furunculosis. Improvement followed treatment with topical mupirocin and cephalexin.At age 45 the patient was diagnosed with BP when he presented with painful bullae on the legs, palms, and torso which were precipitated by minimal skin trauma. His medications at that time were mesalamine, prednisone, and ursodiol, none of which had been initiated recently. Examination revealed small areas of desquamation of the palms and erythematous patches with bullae and peripheral scale on the torso and legs.Biopsy revealed a subepidermal blister with a sparse, mixed inflammatory infiltrate, consistent with a subepidermal blistering disorder such as BP (Figure 2).Biopsies from the oral lesions which developed at age 22 were reviewed in light of his recently dia...