Deep pyogranulomatous folliculitis found on the bilateral heels of a cat by an histopathological examination

Abstract

An eleven-month-old castrated Japanese cat presented with hemorrhage and ulcer in the bilateral calcaneal regions. A histopathologic examination suggested cystic expansion of infundibular hair follicles that were filled with cuticles and a few fragments of hair roots. Non-permanent hair roots in the deep dermis were fragmented, and neutrophils, macrophages and multinucleated giant cells had infiltrated diffusely, forming a large granulomatous lesion in the subcutaneous tissues. The cytoplasm of a few multinucleated giant cells included fragments of hair roots. In residual follicles, dehiscence of epithelial hair follicles and infiltration of inflammatory cells as described above were observed.