Multiple Histiocytic Foam Cell Nodules in the Tongue of Miniature Dachshund Dogs.

Miniature dachshund dogs are a common breed in Japan and are known to be predisposed to granulomatous diseases. Here we report the pathologic features of multiple lingual nodules in 7 miniature dachshunds. Seven dogs had multiple nodules of variable sizes mainly on the ventral and lateral surface of the tongue. In addition, 1 dog also had masses on the left oral mucosa. Three cases had recurrence after surgical resection. Histologically, the lingual nodules were composed of aggregates of foam cells with clear vacuolated cytoplasm that were negative for oil red O, PAS, and alcian blue. They stained positively for CD204 (macrophage scavenger receptor) and MHC class II and negatively for Iba-1, E-cadherin, adipophilin, cytokeratins, S-100, and nestin. These findings indicate that the multiple lingual nodules in miniature dachshunds are an unusual, unique lesion consisting of macrophage-derived foam cells, which does not correspond to canine lingual diseases reported to date.