Alimentary squamous cell carcinoma in psittacines: 12 cases and review of the literature

Abstract

Squamous cell carcinoma (SCC), which is a neoplasm that usually arises from the integument, is reported uncommonly in pet birds. Only a few reports of SCCs in the alimentary tract of birds, including psittacines, have been published, and a detailed description of the pathology is not available in the literature. We present here 12 cases of alimentary SCC in psittacines. The average age of the birds was 22.2 y (range: 15–29 y), and affected species included 4 Amazon parrots ( Amazona sp.), 3 cockatiels ( Nymphicus hollandicus), 3 macaws ( Ara sp.), 1 conure ( Eupsittula sp.), and 1 Senegal parrot ( Poicephalus sp.). Frequent clinical complaints included regurgitation, dysphagia, dyspnea, lethargy, and/or weight loss. SCC primarily affected the oral cavity in 6 of 12 cases, the crop alone in 2 of 12 cases, the crop and esophagus in 1 of 12 cases, the proventriculus alone in 1 of 12 cases, and the crop, esophagus, and proventriculus in 2 of 12 cases. Histologically, alimentary SCCs were locally invasive and often resulted in mucosal ulceration. Although there were no metastases in any of our cases, poor clinical outcomes were frequent and associated most commonly with complete effacement of the alimentary segment and severe inflammation with opportunistic bacterial infection. Our review of the literature records commonly affected species, variability of gross presentations and clinical signs, plausible etiologies, and current diagnostic developments.

Survey of the Clinical, Cytological, and Histopathological Features Associated with Neoplasms in Captive Avian Species in Melbourne, Australia

“…3,46 Although uropygial gland SCC has been reported in multiple psittacine species, it appears to be most common in chickens. 3,46,65,66,[95][96][97][98][99][100][101] However, we did not identify any cases of uropygial gland SCC in this species despite chickens representing over one-half of our study population. The median age of birds affected by uropygial gland neoplasia in our study was 8 years (range, 1-61 years).…”

“…Common sites of avian SCC development include the skin, the oral cavity and crop, and the uropygial gland. 95,100 These neoplasms are commonly observed in numerous avian species. 1,2,[95][96][97][98][99][100][101][102][103][104][105][106][107][108] For parrots, our findings were in agreement with previous work, with 4 cases of SCC diagnosed in the uropygial gland and 1 as a dermal mass on the wing.…”

“…95,100 These neoplasms are commonly observed in numerous avian species. 1,2,[95][96][97][98][99][100][101][102][103][104][105][106][107][108] For parrots, our findings were in agreement with previous work, with 4 cases of SCC diagnosed in the uropygial gland and 1 as a dermal mass on the wing. In chickens, SCC occurs infrequently, but there have been reports of dermal lesions on the legs with a benign biological behavior that spontaneously resolve, 19 malignant generalized skin ulceration (avian keratoacanthoma), 109,110 and lesions in the oropharynx and upper gastrointestinal tract.…”

Adenocarcinoma of the distal esophagus and esophageal-proventricular junction in a yellow-naped parrot

“… 2 , 11 , 13 Alimentary SCC is described in Amazona sp., Nymphicus hollandicus , Ara sp., Eupsittula sp., and Poicephalus sp., in the oral cavity, crop, esophagus, and proventriculus, and is associated with regurgitation, dysphagia, dyspnea, lethargy, and weight loss. 1 Secondary bacterial infection of the ulcerated mucosa with associated poor clinical outcomes is common in psittacine alimentary SCCs. 1 Esophageal and crop papilloma is reported in macaws and amazon parrots, leiomyomas and leiomyosarcomas are infrequently reported in the crop and alimentary tract (not further specified) of budgies and lovebirds, and fibrosarcomas are reportedly rare in the esophagus and alimentary tract (not further specified) of budgies and parrots.…”

“… 1 Secondary bacterial infection of the ulcerated mucosa with associated poor clinical outcomes is common in psittacine alimentary SCCs. 1 Esophageal and crop papilloma is reported in macaws and amazon parrots, leiomyomas and leiomyosarcomas are infrequently reported in the crop and alimentary tract (not further specified) of budgies and lovebirds, and fibrosarcomas are reportedly rare in the esophagus and alimentary tract (not further specified) of budgies and parrots. 8 , 11 , 14 There is limited literature on carcinomas arising from the esophageal submucosal glands, 11 with no published case reports of this entity, to our knowledge.…”