Squamous cell carcinoma of the epidermis in an aged white-lipped tamarin (Saguinus fuscicollis leucogenys Gray).

Abstract

The disparity between the incidence of neoplasms in non-human primates and man has received considerable attention. Although longer survival times in captivity in recent years apparently have resulted in more and different neoplasms, a considerable gap remains between the neoplasm incidence in man and other primate species. Few neoplasms have been reported in the Cullithricids [ 1, 4, 6, 101. A female white-lipped tamarin had conjunctivitis of the left eye which was treated with topical antibiotics. Systemic antibiotics also were given for I week because she was febrile (41.0' C) and pneumonia was suspected. She was observed periodically for 3 months and then discharged. Seven months later she presented with a dry left eye and left-sided facial nerve palsy including paralysis of the orbicularis oculi muscle. A normal Bell's phenomenon was present when the eye was menaced. A firm 4-millimeter, slightly elevated ulcerated lesion was in the skin on the left side of the neck just ventral to the intertragic notch of the ear. Bacterial cultures were taken and the lesion was treated for I week with topical antibacterial agents. The lesion did not heal and was biopsied. The diagnosis was invasive squamous cell carcinoma of the epidermis. The neoplasm grew rapidly and 3 weeks later had extended down the neck around the angle of the left mandible, encroached upon the buccal cavity, and interfered with occlusion of the teeth on the left side. She began to lose condition and was killed and necropsied. A tough, pale yellow, finely trabeculated mass extended about 2 centimeters from the primary lesion down the neck and invaded the muscles of the neck, the parotid salivary gland, and the muscles of the ascending ramus of the left mandible. The primary site remained as an ulcer about 5 millimeters in diameter. There was a slight cauliflower lip along the margin. The regional lymph nodes were two to four times normal size. Tissues from all visceral organs, brain, spinal cord and neoplasm were futed in 10% neutral buffered formalin and processed for histological examination. Stains included hematoxylin and eosin (HE), periodic acid-Schiff (PAS) and Masson's trichrome. The cells along the margin of the neoplasm were spindle shaped and were fairly distinct from the adjacent hyperplastic epithelium (fig. 1). Branching cords of neoplastic cells extended through the dermis into the underlying soft tissues (fig. 2). The neoplastic cells were polyhedral, had prominent intercellular bridges, abundant eosinophilic cytoplasm and large vesicular nuclei with one or two prominent nucleoli. Mitotic figures were common. Some cells beneath the keratohyaline droplet cell layer of the upper strata of cystic structures contained PASpositive cytoplasmic droplets. Six regional lymph nodes were examined. Three were reactive and two had early sinus histiocytosis, but none had metastases. Metastases were not found in any of the visceral organs or central nervous system. The clinical course was rapid but metastasis had not occurred when the tamarin was killed. Squamous cell carcinomas arising in the head and neck region in man are considered by some [ 1 I] to be more highly malignant than those arising elsewhere. This neoplasm therefore could have existed during the preceding illness and was missed because of the long pelage around the jowls and neck in this species. Left facial palsy indicates encroachment upon the facial