Sublingual reactive histiocytosis in a dog

Area of Science:

• Veterinary Pathology
• Canine Dermatology
• Immunohistochemistry

Background:

• Lingual lesions in dogs are uncommon, often linked to neoplasms, trauma, or infections.
• Reactive histiocytosis is a poorly understood disorder involving activated dendritic cells, lymphocytes, and neutrophils, with a characteristic angiocentric pattern.
• This condition can exhibit fluctuating clinical behavior, with potential for regression or systemic involvement.

Observation:

• A case report details an unusual sublingual presentation of reactive histiocytosis in a Miniature Pinscher.
• Diagnosis was confirmed through clinical and histopathological exclusion, identification of the characteristic microscopic pattern, and immunocytochemistry.
• Immunohistochemistry revealed histiocytic cells positive for vimentin, CD18, CD11c, and CD1c, supporting a dendritic cell origin.

Findings:

• The sublingual mass in the dog was diagnosed as reactive histiocytosis.
• Immunohistochemical markers confirmed the dendritic cell nature of the proliferating cells.
• The anti-Bacillus Calmette and Guerin (BCG) stain was negative, ruling out specific etiological agents.

Implications:

• This case highlights an unusual sublingual manifestation of reactive histiocytosis in dogs.
• Successful treatment with oral tetracycline and niacinamide was observed over an 8-month period.
• The absence of recurrence two years post-treatment suggests a favorable prognosis with this therapeutic approach for canine reactive histiocytosis.