Multiple Cutaneous Inverted Papilloma in a German Shepherd Dog

Case Description- In this clinical report, occurrence of a rare case of canine cutaneous inverted papilloma was discussed. A 4-year-old, intact, male German shepherd dog was presented with multiple skin lesions, located on the inguinal region near the root of penis, which have been progressively growing since two months ago. In close examination of the lesions multiple, firm, painful, and cup-shaped nodules in different sizes with a central pore filled with keratin were observed. Treatment and Outcome- Surgical excision and histological evaluation was done.  Histologically this tumor was characterized by endophytic projections of the epidermis extending into dermis.Cytopathic effects included ballooning degeneration of keratinocytes, koilocytosis, irregularity of keratohyalin granules, and margination of nuclear chromatin. Numerous eosinophilic intranuclear inclusions were present within keratinocytes of endophytic lesion. Immunohistochemically, the tumor cells were intensely positive for pancytokeratin. On the basis of histopathological and clinical findings, the tumor was diagnosed as multiple cutaneous inverted papilloma. There was no recurrence or any other complications in post operative monitoring. Clinical Relevance- Inverted papillomas are relatively uncommon in dogs; whereas, the incidence of this tumor in the inguinal region is uncommon. Treatment of inverted papilloma was completed by surgical excision in ablating the tumor masses and preventing re-growth.