title: A "down under" lesion on the muzzle of a dog.
abstract: A 10-year-old, castrated, male Labrador Retriever was presented to a local veterinary practice for investigation of a firm, deeply pigmented, alopecic, subcutaneous mass (8 mm in diameter) on the left side of the muzzle. A fine-needle aspirate of the mass was submitted for cytologic evaluation to the University of Florida. Microscopically, the preparation contained a predominant population of histiocytes that contained variable numbers of intracytoplasmic, negative-staining, filamentous structures consistent with Mycobacterium sp. A presumptive diagnosis of canine leproid granuloma syndrome was based on the cytologic findings and location of the lesion. Acid-fast staining revealed bright pink, acid-fast organisms within the histiocytic cells, supporting the diagnosis. The bacteria were not detected in histopathologic sections or by a polymerase chain reaction (PCR) test 1 week later, however, possibly because of spontaneous remission. Canine leproid granuloma syndrome is a common disease in Australia, but is uncommon in dogs in North America. It is caused by a novel, unnamed Mycobacterium species and usually affects the skin and subcutaneous tissues of the head and ears. A diagnosis usually can be made in Wright's-Giemsa and acid-fast-stained cytologic specimens; however, definitive diagnosis requires PCR testing at a specialized laboratory.
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA. twomeyl@mail.vetmed.ufl.edu
authors.forename: Leanne N
authors.initials: LN
authors.lastname: Twomey
authors.forename: Julia A
authors.initials: JA
authors.lastname: Wuerz
authors.forename: A Rick
authors.initials: AR
authors.lastname: Alleman
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000382:microbiology* / Q000473:pathology*; D004285:Dogs; D006099:Granuloma / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D008297:Male; D009161:Mycobacterium / Q000302:isolation & purification; D009164:Mycobacterium Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D013194:Staining and Labeling