A 61-year-old man sought medical attention when tense blisters started to develop on his abdomen, groin, thighs, and forelegs. He was in good health, and took no medications.
Key point: In the older age group, the most likely diagnosis is bullous pemphigoid, an autoimmune blistering disorder. Biopsy and both direct and indirect immunofluorescent tests (which detect and characterize circulating autoantibodies) may be necessary to exclude other blistering diseases, which appear similar in morphology: pemphigus and acquired epidermolysis bullosa. Oral lesions may also be present, although blisters in this area usually rupture early, leaving behind shallow, painful erosions.
Treatment: Application of ultra-high potency topical corticosteroids is indicated. If resolution is not prompt, then systemic corticosteroids, with or without immunosuppressive drugs (such as mycophenolate mofetil, azathioprine, or methotrexate) may be employed.
Note: Adequate treatment is critical because the erosions, which follow blister rupture, are excellent portals of entry for bacteria. Sepsis is the usual cause of death.
A hematologically stable CML patient developed a solitary, exquisitely painful ulceration, 7 cm × 5 cm, located on the mid-medial foreleg. There was never any evidence of venous insufficiency. The patient denied the possibility of a spider bite. What is the likely cause of this lesion?
