Uterine Epithelioid Trophoblastic Tumour in a Red-tailed Guenon (Cercopithecus ascanius)

Proceedings of the 2018 National Toxicology Program Satellite Symposium

The 2018 annual National Toxicology Program Satellite Symposium, entitled "Pathology Potpourri," was held in Indianapolis, Indiana, at the Society of Toxicologic Pathology's 37th annual meeting. The goal of this symposium was to present and discuss challenging diagnostic pathology and/or nomenclature issues. This article presents summaries of the speakers' talks along with select images that were used by the audience for voting and discussion. Various lesions and other topics covered during the symposium included seminiferous tubule dysgenesis in rats, ameloblast and odontoblast degeneration/necrosis in a Sprague Dawley rat, intestinal leiomyositis in a beagle dog, gallbladder mucinous hyperplasia, focus of hepatocellular alteration and bile duct alteration in otters, renal tubule cytoplasmic vacuolation with basophilic granules in mice treated swith antisense oligonucleotide therapy, a uterine choriocarcinoma in a rhesus macaque, and rete ovarii proliferative ovarian lesions in various aged rat strains. One particularly provocative lesion was a malignant neoplastic proliferation in the renal pelvic region of a cynomolgus macaque from a 21-day study. Additional challenging lesions included thyroid proliferative lesions in zebra fish and gross findings in fish larvae during routine chemical screening. The Rabbit and Minipig International Harmonization of Nomenclature and Diagnostic Criteria Organ Working Groups also presented a series of challenging lesions.

Benign placental mass with fetal growth retardation in a bull mastiff

A 4-year-old bull mastiff presented due to premature labour. The referring veterinarian elected to perform a caesarian delivery and at the time of surgery a 4×4×2 cm round, smooth, red to tan, lobulated soft mass was identified attached to the allantoic surface of the zonary placenta of one pup. Microscopically, this mass was composed of loosely arranged confluent undulating cords of polygonal to columnar epithelioid cells separated by a fine fibrovascular stroma resembling the placental labyrinth. The labyrinthine structure and epithelioid nature of the cells suggested that the mass was of trophoblastic origin. Due to the non-invasive nature of the mass and relatively low mitotic activity, this proliferative trophoblastic mass was considered to be benign. The absence of morphological features supporting malignant behaviour and the recapitulation of the normal labyrinthine architecture led to the diagnosis of a trophoblastic hamartoma. To the authors' knowledge this is the first report of a placental hamartoma in the dog.

Selected Background Findings and Interpretation of Common Lesions in the Female Reproductive System in Macaques

The authors describe a selection of normal findings and common naturally occurring lesions in the reproductive system of female macaques, including changes in the ovaries, uterus, cervix, vagina, and mammary glands. Normal features of immature ovaries, uteri, and mammary glands are described. Common non-neoplastic lesions in the ovaries include cortical mineralization, polyovular follicles, cysts, ovarian surface epithelial hyperplasia, and ectopic ovarian tissue. Ovarian neoplasms include granulosa cell tumors, teratomas, and ovarian surface epithelial tumors. Common non-neoplastic uterine findings include loss of features of normal cyclicity, abnormal bleeding, adenomyosis, endometriosis, epithelial plaques, and pregnancy-associated vascular remodeling. Hyperplastic and neoplastic lesions of the uterus include endometrial polyps, leiomyomas, and rarely endometrial hyperplasia and endometrial adenocarcinoma. Vaginitis is common. Cervical lesions include endocervical squamous metaplasia, polyps, and papillomavirus-associated lesions. Lesions in the mammary gland are most often proliferative and range from ductal hyperplasia to invasive carcinoma. Challenges to interpretation include the normal or pathologic absence of menstrual cyclicity and the potential misinterpretation of sporadic lesions, such as epithelial plaques or papillomavirus-associated lesions. Interpretation of normal and pathologic findings is best accomplished with knowledge of the life stage, reproductive history, and hormonal status of the animal.

Trophoblast-like cells in the tissues of porcupines (Erethizon dorsatum)

During development and subsequent field evaluation of an oral vaccinia-rabies glycoprotein (V-RG) recombinant virus vaccine, 53 adult porcupines (Erethizon dorsatum; 38 females and 15 males) were examined. Microscopic examinations revealed the presence of giant epitheloid cells in various tissues (adrenal glands, spleen, liver, and lungs) of 4 (11%) female animals. These giant cells were approximately 20 times the size of the surrounding cells of the parenchyma. The cells were found singly and were not associated with any inflammatory cellular infiltrate and appeared to be located within vascular lumina. Morphologically these cells were typical of uterine epitheloid trophoblasts. This is the first record of the presence of trophoblast-like cells in nongenital tissues of porcupines.

Spontaneous lesions in the reproductive tract and mammary gland of female non-human primates

Because of their close phylogenic relationship with humans, the use of non-human primates (NHP) as experimental subjects has a long history in biomedical research. Although research topics have shifted focus and species used have changed, NHP remain vital as models in basic and applied research. While there is a wealth of information available on the spontaneous lesions of NHP, most of this information is fragmented, dated, or narrow in focus, often limited to single case reports. This review attempts to integrate this information to illustrate and enumerate the spectrum of spontaneous pathology of the reproductive tract and mammary gland of NHP. Although not the focus of this review, steroid-related changes are inextricably linked to these tissues, and brief consideration is given to this subject as well.