Immunohistochemical Characterization of a Duodenal Adenocarcinoma with Pulmonary, Hepatic and Parapatellar Metastases in a Common Marmoset (Callithrixjacchus)

Abstract

An 11-year-old male common marmoset (Callithrix jacchus) presented with chronic, progressive weight loss and diarrhoea. Response to treatment with nutritional supplementation, antibiotics and immunosuppressants was modest and transient, and the animal was humanely euthanized. At necropsy, the proximal 8 cm of small intestine was diffusely pale with transmural thickening. The lungs contained coalescing tan, firm nodules measuring up to 4 mm in diameter. Histological examination revealed infiltrative mucinous adenocarcinoma of the duodenum with extensive metastases to the lungs, liver and left parapatellar adipose tissue. The mucinous matrix secreted by the primary and metastatic lesions was strongly periodic acid-Schiff positive. Warthin Starry staining for spirochaetes was negative. Pancytokeratin expression was attenuated in the primary tumour as well as in the metastases, which correlated to a poorly differentiated phenotype. To the authors' knowledge, this is the first report of a proximal duodenal adenocarcinoma with extensive metastatic disease in a common marmoset.

Keywords: common marmoset; duodenal mucinous adenocarcinoma; metastases; pancytokeratin.

Fig. 1.

Bodyweight of affected common marmoset from presentation in May 2020 (A) to euthanasia in March 2021 (E). Treatment with nutritional supplementation, metronidazole (50 mg/kg PO q24h for 14 days) and budesonide (0.5 mg PO q24h) was initiated in June 2020 (B). Following refractory weight loss, treatment with metronidazole (50 mg/kg PO q24h for 7 days) and prednisolone (2 mg/kg PO q24h) was initiated in July 2020 (C). Prednisolone was tapered and discontinued, and budesonide therapy was reinstituted in November 2020 (D) following a period of clinical decline.

Fig. 2.

Primary mucinous duodenal adenocarcinoma, duodenum, common marmoset. HE. Bar, 50 μm. (a) Neoplastic cells expand and infiltrate the duodenum transmurally. (b) Higher magnification of boxed area from (a) demonstrating neoplastic epithelial cells, arranged in acini, infiltrating through the muscularis mucosa. (c) Neoplastic cells have a more spindloid shape, admixed with clusters of epithelial acini, in serosa. (d) Multifocal neoplastic emboli within lymphatics.

Fig. 3.

Metastatic mucinous duodenal adenocarcinoma, common marmoset. HE. Bar, 50 μm. Metastases to lungs (a), liver (b) and left parapatellar adipose tissue (c). Neoplastic cell morphology and mixed inflammatory cells are similar to primary duodenal lesion.

Fig. 4.

Duodenal and metastatic carcinoma, common marmoset. Immunolabelling with anti-pancytokeratin (a, e, i, m), IBA1 (b, f, j, n), CD3 (c, g, k, o) and CD20 (d, h, l, p). Bar, 50 μm. Top row: primary duodenal adenocarcinoma with paucity of labelling for pancytokeratin (a) and moderate intratumoural infiltrates of macrophages (b), T cells (c) and B cells (d). Second row: pulmonary metastases with absence of pancytokeratin expression as in primary lesion (e) and moderate intratumoural macrophage infiltrates (f). No immunolabelling for CD3 (g) or CD20 (h). Third row: hepatic metastases with absence of pancytokeratin expression (i) and moderate intratumoural infiltrates of macrophages (j), T cells (k) and B cells (l). Fourth row: parapatellar metastases with attenuated pancytokeratin expression (m) and moderate numbers of infiltrating macrophages (n). No immunolabelling for CD3 (o) or CD20 (p).