Combination of a teratoma and embryonal carcinoma of the testis in SD IGS rats: a report of two cases

Testicular Teratocarcinoma in a Ferret (Mustela putorius furo)

A 7-month-old male domestic ferret (Mustela putorius furo) was presented for evaluation of unilateral testicular enlargement. Microscopic examination of the left testicle revealed a neoplasm with differentiation along multiple cell lines (ectoderm, endoderm, mesoderm) including respiratory epithelium, bone and haired skin. A poorly differentiated epithelial component was dispersed throughout the neoplasm with invasion of testicular lymphatics. The animal developed progressive dysuria and was euthanized. At necropsy, metastasis of the poorly differentiated epithelial component was present in the urinary bladder, ureters, prostate gland, pelvic fat, abdominal and thoracic lymph nodes, kidney and lung. This is the first report of a malignant testicular teratoma with widespread metastasis in this species.

Metastatic Mixed Germ Cell Tumour with Embryonal Carcinoma and Choriocarcinoma in a Female Eurasian Harvest Mouse (Micromys minutus)

Mixed germ cell tumours occur rarely in veterinary species. This report describes a case of metastatic mixed germ cell tumour in a female Eurasian harvest mouse (Micromys minutus). The tumour was extensive in one ovary and the uterus, and was characterized by two distinct tumour cell populations with features typical of embryonal carcinoma (EC) and choriocarcinoma (CC). Metastases of CC to the lungs and liver were observed. The exact origin of the CC was unclear, but the possibility of a non-gestational CC is favoured, given the context of a mixed germ cell tumour and lack of p53 expression. EC diagnosis was confirmed by immunohistochemical labelling of CD30 and lack of immunoreactivity for c-Kit. In addition, membranous β-catenin expression was present in the EC component, indicating an inactive Wnt/β-catenin pathway, which is required for the maintenance of pluripotency.

Proliferative and nonproliferative lesions of the rat and mouse male reproductive system

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature and differential diagnosis for classifying microscopic lesions observed in the male reproductive system of laboratory rats and mice, with color microphotographs illustrating examples of some lesions. The standardized nomenclature presented in this document is also available for society members electronically on the Internet (http://goreni.org). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and aging lesions as well as lesions induced by exposure to test materials. A widely accepted and utilized international harmonization of nomenclature for lesions of the male reproductive system in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Spontaneous Nonmetastatic Choriocarcinoma, Yolk Sac Carcinoma, Embryonal Carcinoma, and Teratoma in the Testes of a Swiss Albino Mouse

A 12-week-old Swiss Albino mouse was presented with unilateral (left) testicular enlargement of approximately 1.5 cm in diameter and the right testicle mildly reduced in size and weight. Histopathology evaluation revealed three distinct neoplasms in the left testicle: choriocarcinoma, yolk sac carcinoma, and embryonal carcinoma. Teratoma was diagnosed in the right testicle. The histomorphological and immunohistochemical characteristics of the tumor are presented here. To the best of the authors’ knowledge, this is the first report of spontaneous nonmetastasizing choriocarcinoma, yolk sac carcinoma, embryonal carcinoma, and teratoma in testes of a Swiss albino mouse.

The ter mutation in the rat Dnd1 gene initiates gonadal teratomas and infertility in both genders

A spontaneous mutation leading to the formation of congenital ovarian and testicular tumors was detected in the WKY/Ztm rat strain. The histological evaluation revealed derivatives from all three germ layers, thereby identifying these tumors as teratomas. Teratocarcinogenesis was accompanied by infertility and the underlying mutation was termed ter. Linkage analysis of 58 (WKY-ter×SPRD-Cu3) F2 rats associated the ter mutation with RNO18 (LOD = 3.25). Sequencing of candidate genes detected a point mutation in exon 4 of the dead-end homolog 1 gene (Dnd1), which introduces a premature stop codon assumed to cause a truncation of the Dnd1 protein. Genotyping of the recessive ter mutation revealed a complete penetrance of teratocarcinogenesis and infertility in homozygous ter rats of both genders. Morphologically non-tumorous testes of homozygous ter males were reduced in both size and weight. This testicular malformation was linked to a lack of spermatogenesis using immunohistochemical and histological staining. Our WKY-Dnd1(ter)/Ztm rat is a novel animal model to investigate gonadal teratocarcinogenesis and the molecular mechanisms involved in germ cell development of both genders.

Mixed germ cell tumor with embryonal carcinoma, choriocarcinoma, and epithelioid trophoblastic tumor in the ovary of a cynomolgus monkey

A seven-year-old female cynomolgus monkey had a mass in the left ovary with metastasis to the lung and the right ovary. The mass of these organs showed three different characteristics, and its immunohistochemical profiles were consistent with embryonal carcinoma (EC), choriocarcinoma (CC), and epithelioid trophoblastic tumor (ETT). The EC was characterized with sheets and glandlike structures with large pleomorphic, single-nucleated epithelial cells that were immunohistochemically positive for α-fetoprotein, octamer-4, and CD30, and with multinucleated giant cells resembling syncytiotrophoblasts. The CC also represented biphasic proliferation of the cytotrophoblast positive for cytokeratin 7 (CK7), which showed negative immunoreactivity for all three of the above antibodies, and it was syncytiotrophoblast positive for human chorionic gonadotropin. The ETT showed numerous floating cells in an abundant eosinophilic extracellular matrix with vacuolated or eosinophilic cytoplasm and was immunohistochemically positive for CK7, p63, and α-inhibin, which features nodule or cordlike structures. Collectively, this neoplasm was identified as a mixed germ cell tumor with EC, CC, and ETT. To our knowledge, this is the first report of EC in nonhuman primates as a component of mixed germ cell tumor.

A Spontaneous Teratocarcinoma in the Testis of a Swiss Albino Mouse

A unilateral non-metastatic embryonal carcinoma and teratoma of the testis was observed in a 12-week-old Swiss Albino mouse at the end of a 28-day repeated dose toxicity study. The teratocarcinoma almost completely replaced the parenchyma of the left testis. The tumor was composed of sheets and rosettes of primitive embryonal cells, anaplastic cells, skeletal muscle tissue, sebaceous gland tissue, keratinized stratified squamous epithelium, and ciliated cuboidal epithelium. The histomorphological characteristics of the tumor were reviewed and presented in this report. To the best of the authors' knowledge, this is the first report of spontaneous teratocarcinoma of testis in the Swiss Albino strain of mice.

Intratubular embryonal carcinoma

Although intratubular embryonal carcinoma has been described adjacent to invasive embryonal carcinoma, to our knowledge it has not been reported as an isolated finding. We present in this report the histologic and immunohistochemical findings of 2 cases of intratubular embryonal carcinoma. One case was exclusively intratubular embryonal carcinoma without an invasive component in the same testis. A malignant mixed germ cell tumor in the contralateral testis had been previously excised. The second case is predominantly composed of intratubular embryonal carcinoma adjacent to a malignant mixed germ cell tumor. In one case, the intratubular embryonal carcinoma was immunoreactive for CD30, AE1/AE3, cytokeratin 7 focally, and p53. It was negative for cytokeratin 20, p21, and alpha-fetoprotein. These findings are strongly supportive of the opinion that intratubular embryonal carcinoma is the precursor of invasive embryonal carcinoma.