Foreign body reaction to ruptured follicular cysts in dogs

Background Cutaneous cysts are common in dogs, and surgical resection is the recommended treatment. However, additional therapy may be required for ruptured follicular cysts with severe cutaneous complications. Case presentation A 3‐year‐old neutered male Samoyed was presented with multifocal masses on the forelimbs. A 5‐year‐old neutered female Maltese was also presented with multiple masses and ruptured lesions, which were ulcerative and painful, around the parotid and submandibular glands. The lesions were examined cytologically. In addition, bacterial and fungal cultures and histopathologic examination were performed. Cutaneous multifocal nodules in the Samoyed could not be diagnosed via cytological examination or bacterial/fungal culture. Histopathology revealed numerous follicular cysts with multiple pyogranulomas of various sizes, some of which contained central keratin debris. In the Maltese, cytologic examination revealed central keratins or enucleated ghost cells in the intact cysts and few keratinized squamous cells mixed with neutrophils, mucus and metachromatic cells in the ruptured cysts. Histopathologic examination revealed severely dilated follicular cysts. Oral steroid and cyclosporine therapy resulted in marked improvement in the aseptic pyogranulomas after 2 weeks in formal case and combined with a surgery for residual cysts in latter case. Conclusions We have reported two canine cases of ruptured follicular cysts causing foreign body‐like aseptic pyogranulomas around cutaneous tissues and their successful management with pharmacological therapy and surgery.