The Mexican Goodeid, Zoogoneticus tequila, is considered nearly extinct in the wild and it s m nt n n pt v ty y t nonprof t nt rn t on l ―Goo Work n Group ‖ pathology survey on the unique Italian colony was previously published by the authors, but no other literature reports regarding pathologies of this species are available. The present case describes an adult female showing a progressive coelomic distension, suggestive of gestation. In fact, Z. tequila is a viviparous species and females give birth to free-swimming fry after an intraovarian gestation. However, after a period of anorexia of two days' duration, the fish died and was immediately submitted to necroscopic and histopathologic exams. Macroscopical examination confirmed the abdominal enlargement, associated with the presence of a mucous secretion from the genital pore. A large multilobulated mass (2x1.5x1 cm) occupied most of the coelomic cavity, causing intestinal occlusion by compression of the intestine without infiltration. Samples of the mass were routinely processed for histology. Additional sections were also subjected to immunohistochemistry for pan-cytokeratin, vimentin, glial fibrillary acidic protein (GFAP), and neuron-specific enolase (NSE). Histologically, the mass consisted of a complex variety of tissues derived from the three germ cell layers, suggesting a diagnosis of teratoma. Structures of ectodermal origin included multifocal, keratinizing squamous epithelium, and large areas of nervous system tissue resembling cerebrum. Mesenchymal tissues (mesodermal origin) consisted of skeletal muscle, cartilage, fibrous connective tissue, and adipose tissue. Numerous, simple-to-branching glandular structures lined by intestinal-type epithelium (endodermal origin) were also admixed. All the epithelial components were pancytokeratin-positive. Extensive neuronal and glial differentiation was confirmed by intense and diffuse immunoreactivity for GFAP and, to a lesser extent, for NSE. In addition, multiple, densely-cellular islands and branching trabeculae of undifferentiated tissue, characterized by mild cellular and nuclear atypia, and sparse mitotic figures, were observed. The presence of sparse residual oocytes in different stages of development indicated an ovarian origin of the tumour. Teratomas are neoplasms containing multiple tissues originating from more than one germ cell layer. They may be classified as benign (mature) or malignant (immature) depending on the degree of anaplasia or the presence of embryonic-like undifferentiated elements. Teratomas are occasionally described in fish, especially in viviparous species, even though they are usually poorly characterized at the histological and immunohistochemical levels. In this case, even though metastatic or implanted masses were not noted, the presence of poorly differentiated elements in addition to mature structures indicate a definitive diagnosis of ovarian immature teratoma.
Ovarian teratoma in an adult female Zoogoneticus tequila (Webb & Miller, 1998): histological and immunohistochemical features
Romanucci M.;Arbuatti A.;Massimini M.;Defourny S.;Della Salda L
2016-01-01
Abstract
The Mexican Goodeid, Zoogoneticus tequila, is considered nearly extinct in the wild and it s m nt n n pt v ty y t nonprof t nt rn t on l ―Goo Work n Group ‖ pathology survey on the unique Italian colony was previously published by the authors, but no other literature reports regarding pathologies of this species are available. The present case describes an adult female showing a progressive coelomic distension, suggestive of gestation. In fact, Z. tequila is a viviparous species and females give birth to free-swimming fry after an intraovarian gestation. However, after a period of anorexia of two days' duration, the fish died and was immediately submitted to necroscopic and histopathologic exams. Macroscopical examination confirmed the abdominal enlargement, associated with the presence of a mucous secretion from the genital pore. A large multilobulated mass (2x1.5x1 cm) occupied most of the coelomic cavity, causing intestinal occlusion by compression of the intestine without infiltration. Samples of the mass were routinely processed for histology. Additional sections were also subjected to immunohistochemistry for pan-cytokeratin, vimentin, glial fibrillary acidic protein (GFAP), and neuron-specific enolase (NSE). Histologically, the mass consisted of a complex variety of tissues derived from the three germ cell layers, suggesting a diagnosis of teratoma. Structures of ectodermal origin included multifocal, keratinizing squamous epithelium, and large areas of nervous system tissue resembling cerebrum. Mesenchymal tissues (mesodermal origin) consisted of skeletal muscle, cartilage, fibrous connective tissue, and adipose tissue. Numerous, simple-to-branching glandular structures lined by intestinal-type epithelium (endodermal origin) were also admixed. All the epithelial components were pancytokeratin-positive. Extensive neuronal and glial differentiation was confirmed by intense and diffuse immunoreactivity for GFAP and, to a lesser extent, for NSE. In addition, multiple, densely-cellular islands and branching trabeculae of undifferentiated tissue, characterized by mild cellular and nuclear atypia, and sparse mitotic figures, were observed. The presence of sparse residual oocytes in different stages of development indicated an ovarian origin of the tumour. Teratomas are neoplasms containing multiple tissues originating from more than one germ cell layer. They may be classified as benign (mature) or malignant (immature) depending on the degree of anaplasia or the presence of embryonic-like undifferentiated elements. Teratomas are occasionally described in fish, especially in viviparous species, even though they are usually poorly characterized at the histological and immunohistochemical levels. In this case, even though metastatic or implanted masses were not noted, the presence of poorly differentiated elements in addition to mature structures indicate a definitive diagnosis of ovarian immature teratoma.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
