Spontaneous Vitiligo in a Captive Rhesus Monkey (Macaca Mulatta)

Abstract

Vitiligo affects a significant portion of human and animal populations. The disease causes irregular and multifocal progressive loss of fur, skin, and mucous membrane pigmentation due to the loss or absence of melanocytes. While etiopathogenesis is not completely understood, autoimmunity, environmental, and genetic factors are implicated We present a case report on a 16-y-old female rhesus macaque (Macaca mulatta ) with depigmented areas that are progressively increasing on the skin and coat and are distributed on the head and back. Histopathology revealed alterations compatible with vitiligo characterized by the absence of melanocytes in the epidermis and dermis. The clinical history and complementary exams support this diagnosis.

Figure 1.

A) Frontal view of the face, highlighting the depigmented area on the left side above the eyes in macaque with vitiligo at 14 y of age. B) Frontal view of the face with highlighting of depigmented areas on both sides above the eyes in macaque with vitiligo at 16 y of age. C) Frontal view of the whole body showing depigmentation only on the left side above the eyes in macaque with vitiligo at 14 y of age. D) Dorsal view of head and back showing depigmentation on both sides above the head and a large band on the side of the right shoulder in macaque with vitiligo at 16 y of age.

Figure 2.

Histologic section stained with hematoxylin and eosin (HE) of macaque with vitiligo at 16 y of age, optical microscopy at 40× magnification. A) Margin of the lesion with the presence of perivascular lymphocyte infiltrates (arrow). B) Inside the lesion, absence of melanin and melanocytes in the dermis and epidermis and depigmented fur. C) Lesion margin with lymphocytic perivascular infiltrate and epidermal hydropic degeneration. D) Epidermis without structural changes, absence of melanin and melanocytes in dermis and epidermis. E) Normal skin showing dermal melanocytes indicated by an arrow.