A case of rapid recurrence of apocrine ductal carcinoma originating from the oral scent gland of a Richardson’s ground squirrel (<i>Urocitellus richardsonii</i>)

Abstract

A 3-year-old female Richardson’s ground squirrel developed a subcutaneous mass at the left oral angle. Seven days after removal of the mass, the mass recurred and metastasized to the cervical lymph node. Histologically, the primary mass was subdivided by fibrous trabeculae into various-sized neoplastic cell lobules showing a solid growth pattern with frequent mitoses and sometimes forming intracytoplasmic lumina. Large to medium-sized lobules formed a central cyst plugged by comedo necrosis. Neoplastic cells showed infiltrative subcutaneous growth. In the recurrent tumor, tubular structures lacking apparent apocrine secretion appeared within the solid growth portion. Neutrophil infiltration was evident within the tubules and intracytoplasmic lumina. Neoplastic cells were diffusely immunopositive for AE1/AE3 pan-cytokeratin (CK) in all lobules and focally positive for CAM5.2 CK in the lobules forming a central cyst and/or tubular structures, but they entirely lacked positivity for the periodic acid Schiff reaction. Ki-67-positive proliferating neoplastic cells were higher in numbers with the recurrent tumor than with the primary tumor. In addition, phosphorylated c-MYC immunoreactivity was observed in neoplastic cell nuclei, distinctly at the portion of invasive growth. Thus, the present case was diagnosed as apocrine ductal carcinoma originating from the oral scent gland, which typically shows highly aggressive biological behavior.

Morphological study of apocrine gland tumors in domestic Richardson’s ground squirrels (Urocitellus richardsonii)

“…8 A previously reported apocrine ductal adenocarcinoma had been suggested to arise from these scent glands. 2 However, no masses arising from anal areas were seen in this study and the locations of the tumors were disproportionately observed in dorsal and perioral skin. This was presumably due to anatomical differences as the oral and dorsal scent glands consist mainly of apocrine epithelium cells, and scent glands of the anal area consist of both apocrine and sebaceous epithelial cells.…”

“…5,17 Ground squirrels are known to have integumentary scent glands located from the perioral region to the cheek ("oral scent glands"), from the cervical skin to dorsal skin ("dorsal glands"), and in the anal region. 2,8 Oral and dorsal scent glands are composed of predominantly apocrine epithelial cells. Marking behaviors such as rubbing the perioral and dorsal areas against the ground or rocks ("twist-marking") and rubbing the corners of the mouth against each other ("greeting") play important roles in the social development of Richardson's ground squirrels.…”

“…8 In 2018, an apocrine ductal carcinoma originating from the oral scent gland was reported for the first time in this species. 2 However, pathological information about tumors originating from these glands remains limited. The goal of this study was to assess the morphological features of these tumors.…”

Doxazosin and Carvedilol Treatment Improves Hepatic Regeneration in a Hamster Model of Cirrhosis

“…In this study, the number of Ki-67-positive cells in the cirrhotic group by CCl4 and placebo were higher than in the group treated with doxazosin. This proliferation marker was identified in cells near the bile ducts of the portal triad, suggesting an increase in immature liver cells, known as ductular response, correlating this increase in cell proliferation with the increase of c-Myc [47–49]…”