COMPARATIVE HISTOPATHOLOGY OF PEMPHIGUS-FOLIACEUS AND SUPERFICIAL FOLLICULITIS IN THE DOG

A comparative histopathologic study of 50 cases of pemphigus foliaceus and 47 cases of superficial folliculitis in the dog was undertaken to identify those histopathologic features important in differentiating these diseases. All cases were diagnosed by the Surgical Pathology Ser vice of the Laboratory of Pathology of the University of Pennsylvania, School of Veterinary Medicine, between January 1986 and March 1991. T hese cases were followed clinically to determine the accuracy of the i nitial histopathologic diagnosis. Data were analyzed by Fisher's exact test for discrete data and the Mann-Whitney U-test for continuous dat a. A probability of <0.05 was considered statistically significant. Th e following breeds were affected with pemphigus foliaceus: Akita, Brit tany Spaniel, Chow Chow, Collie, Dachshund, Doberman Pinscher, English Cocker Spaniel, English Setter, Golden Retriever, Siberian Husky, Lab orador Retriever, Miniature Schnauzer, Old English Sheepdog, Scottish Terrier, Chinese Shar Pei, Spitz, Shetland Sheep Dog, Weimeraner, and West Highland White Terrier. An increased risk of developing pemphigus foliaceus was noted in the Akita (OR = 37.8), English Springer Spanie l (OR = 20.7), Chow Chow (OR = 12.3), Chinese Shar Pei (OR = 7.9), and Collie (OR = 3.9). Pemphigus foliaceus had a higher average density o f acantholytic cells (226 +/- 22.9) than superficial folliculitis(11.8 +/- 4.6), and acantholytic cells were 183 times more likely to be pre sent in pemphigus foliaceus. The presence of rafts of acantholytic cel ls occurred in pemphigus foliaceus (23/50) more often than superficial folliculitis (1/47). Recornification and reformation of pustules were , respectively, 13.4 and 3.6 times more likely to occur in pemphigus f oliaceus. Finally, a longer pustule that bridges multiple hair follicl es (2.3 +/- 0.20 mm and 1.31 +/- 0.10 mm, respectively) was seen in pe mphigus foliaceus.