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Epidermolysis bullosa simplex (EBS) is an inherited skin disorder characterized by increased skin and mucous membrane fragility. Most cases are caused by mutations in keratin 5 ( KRT5 ) and keratin 14 ( KRT14 ). Mutations of these genes result in cytoskeletal disruption of the basal keratinocytes. Gross and histopathologic findings of 2 clinically affected homozygous rhesus macaques with an insertion variant mutation in KRT5 are described and compared with 6 deceased phenotypically normal animals that were heterozygous for the KRT5 insertion variant. Animals that were homozygous for the KRT5 insertion variant were stillborn and had widespread loss of the epidermis. Microscopic examination confirmed severe ulceration and basal cell vacuolation with basilar vesicle formation in the remaining intact epidermis. Immunohistochemistry for cytokeratin 5 demonstrated lack of epidermal immunoreactivity in homozygotes. DNA sequencing identified a 34-base pair insertion variant in exon 5 of the KRT5 gene. To our knowledge, this is the first report of epidermolysis bullosa in rhesus macaques.

Pheochromocytoma, a rarely reported adrenal gland neoplasm in Old World primates, was diagnosed in 5 rhesus macaques (Macaca mulatta) and 2 African green monkeys (Chlorocebus aethiops) from 3 research institutions. Age and sex were available for 6 primates. Two males and 4 females were affected, ranging in age from 9 to 31 years. All neoplasms were unilateral and, in the cases reporting the affected gland, 4 involved the right adrenal gland and 2 involved the left. Diagnosis was established by characteristic histologic features. Immunohistochemically, neoplastic cells in all cases expressed chromogranin A and met-enkephalin and were negative for melan-A and inhibin. Six of 7 tumors were positive for β-endorphin. Pulmonary metastases were present in 2 rhesus macaques and portal vein invasion in 1 African green monkey. To the authors' knowledge, this is the first report of malignant pheochromocytoma in Old World primates., (© The Author(s) 2016.)

Epulides account for 0-7.8% of tumors in surveys of feline oral neoplasms. A review of the literature revealed no reports of multiple epulides in cats. Multiple, concurrent epulides were diagnosed microscopically in 13 cats. Fibromatous and ossifying epulides were diagnosed in 11 of 13 cats and fibromatous epulides were diagnosed in 2 of 13 cats. Microscopically, these epulides were nonencapsulated, well-vascularized, infiltrative, highly cellular neoplasms that expanded the gingiva and were composed of haphazardly arranged, spindle-shaped to stellate cells amid a dense, collagenous stroma. Osseous foci were a feature in the fibromatous and ossifying epulides. The mitotic rate was low and there was marked hyperplasia of the overlying gingiva with a prominent downgrowth of epithelial cords. These tumors recurred in 8 of 13 cats following surgical excision. While uncommon, multiple epulides in cats have a high incidence of recurrence but do not appear to have metastatic potential.