# Surgical Excision of an Extratesticular Anaplastic Carcinoma in a Variable Kingsnake (Lampropeltis mexicana)

## TL;DR

A male variable kingsnake was diagnosed with a rare extratesticular anaplastic carcinoma, the first of its kind reported in snakes.

## Contribution

This is the first documented case of extratesticular anaplastic carcinoma in the male genital apparatus of a snake.

## Key findings

- The tumor was identified as extratesticular anaplastic carcinoma through histological and immunohistochemical analysis.
- The neoplastic cells were positive for cytokeratin but not vimentin, with PAS staining showing granular cells characteristic of efferent ducts.
- This case represents the first reported occurrence of such a tumor in the male genital system of snakes.

## Abstract

An adult male variable kingsnake was examined for a three-week history of anorexia and body deformities, revealing poor condition and an intracoelomic mass. With the owner’s consent, an exploratory celiotomy was performed to remove the mass, which was identified as an undifferentiated tumour by modified Wright–Giemsa stain smears. Histological examination revealed a solid proliferation of highly tubular anaplastic cells and plurinucleated cells positive for cytokeratin and vascular endothelial growth factor, but not vimentin. Periodic acid–Schiff staining showed large granular cells characteristic of efferent ducts. A diagnosis of extratesticular anaplastic carcinoma was made as the first reported case in the male genital apparatus of snakes.

An adult male variable kingsnake (Lampropeltis mexicana) was presented for examination due to a three-week history of anorexia and obvious body deformities. On objective examination the animal was in poor condition, and on palpation, an intracoelomic mass was noted approximately in the distal third of the body, cranial to the cloaca. In agreement with the owner, an exploratory celiotomy was planned and performed and the mass was surgically removed. Modified Wright–Giemsa stain impression smears were taken, which were consistent with an undifferentiated tumour. Histological examination revealed the presence of a solid proliferation composed of highly tubular anaplastic cells and abundant multinucleated cells. The neoplastic cells were positive for cytokeratin (AE1/AE3), but not for vimentin. Periodic acid–Schiff (PAS) staining revealed the presence of large granular cells, which can be identified as the characteristic cells of the efferent ducts. Based on the morphological and immunohistochemical findings, the diagnosis of extratesticular anaplastic carcinoma was made. To the authors’ knowledge, this type of neoplasm has never been reported in the male genital apparatus of snakes.