B. Banco

Immunohistochemical expression of the KIT protein (CD117) in normal and neoplastic canine testes.

The aim of the present study was to characterize the expression of the KIT protein (CD117) in normal and neoplastic canine testes. Archival samples of normal testis (n=5), interstitial cell tumours (ICTs; n=10), Sertoli cell tumours (SCTs; n=10) and seminomas (n=10) were selected. Seminomas were subclassified on the basis of expression of placental alkaline phosphatase (PLAP) as classical seminoma (SE; PLAP positive; n=5) or spermatocytic seminoma (SS; PLAP negative; n=5). In normal testes, KIT expression was observed in Leydig cells and in spermatogonia. All ICTs expressed KIT, but no SCT was positively labelled. Seven of 10 seminomas expressed KIT and these tumours were reclassified on this basis as SS (KIT negative) or SE (KIT positive). These findings are consistent with observations of SE in man where many of the neoplastic cells reach the stage of spermatogonia where PLAP expression is lost and that of KIT is maintained. It would therefore appear that immunolabelling for KIT expression is a more appropriate means of distinguishing between canine SE and SS.

Immunohistochemical Evaluation of the Expression of Anti-Müllerian Hormone in Mature, Immature and Neoplastic Canine Sertoli Cells

In mammals, the earliest specific protein expressed by Sertoli cells (SCs) is the anti-Müllerian hormone (AMH), which induces the regression of Müllerian ducts and is produced by SCs until the functional maturation of the testes. The aim of this study was to evaluate the expression of AMH by canine SCs during testicular maturation and neoplastic transformation. Testes from two fetuses, 18 newborn puppies, five puppies aged 43-180 days and six adult dogs, and 24 canine Sertoli cell tumours (SCTs) were studied immunohistochemically for expression of AMH. Fifteen of the 24 SCTs were classified as typical, eight as lipid-rich and one was considered malignant based on evidence of lymph node metastasis. SCs from fetuses and neonatal puppies and puppies up to 45 days old expressed AMH, while SCs from older puppies and adults were negative. All SCTs expressed AMH, suggesting that AMH expression is a useful marker of immature and neoplastic canine SCs.

An Immunohistochemical Study of Normal and Neoplastic Canine Sertoli Cells

Immunohistochemical studies of human fetal Sertoli cells (SCs) have shown transient expression of cytokeratin (CK) and desmin (DES) that is replaced after birth by expression of vimentin (VIM) and inhibin-α (INH-α). Human Sertoli cell tumours (SCTs) are characterized by re-expression of CK and DES. The aim of the present study was to evaluate immunohistochemically the expression of VIM, INH-α, CK and DES in normal and neoplastic canine SCs. Normal testicular tissue from three adult dogs, one 6-month-old puppy and two neonatal pups was examined in addition to samples from 21 canine SCTs. VIM was not expressed by neonatal SCs, but was present in SCs from the puppy, the adult dogs and in all SCTs. Conversely, INH-α was expressed by neonatal SCs and most SCTs, but not by normal SCs of adult dogs and the puppy. DES and CK were expressed only by some SCTs. These results show that, contrary to findings in man, canine SCs do not express VIM at the time of birth. SCs from neonatal dogs do express INH-α, but such expression was lost in the puppy and the adult dogs. Canine SCs therefore differ from human SCs, as expression of INH-α characterizes immature SCs, whereas the expression of VIM characterizes mature SCs. Canine SCTs may express CK and DES, suggesting that the neoplastic cells undergo de-differentiation during transformation.

Immunohistochemical Expression of Markers of Immaturity in Sertoli and Seminal Cells in Canine Testicular Atrophy

During maturation from fetal to adult testis, both Sertoli cells (SCs) and germ cells (GCs) switch from an immature to a mature immunophenotype. Immature canine SCs express cytokeratins (CKs), desmin (DES), vimentin (VIM), anti-Müllerian hormone (AMH) and inhibin (INH)-α, while mature SCs retain only expression of VIM. Immature GCs express placental alkaline phosphatase (PLAP), which is lost in spermatocytes. Re-expression of markers of immaturity has been observed in human atrophic testes and in human and canine testicular tumours. In human medicine, testicular atrophy is considered a risk factor for testicular cancer. In the present study 13 canine atrophic testes were examined immunohistochemically. VIM was expressed in the SCs of all cases, while CK, DES, INH-α and AMH were expressed in a variable percentage of SCs in two, five, five and eight cases, respectively. PLAP was expressed by single GCs in one case. Markers of immaturity are therefore expressed by SCs and GCs in canine atrophic testes. Similar results were reported previously in canine testicular neoplasia, suggesting that testicular atrophy may represent a risk factor for tumour development in the dog.

Metastasizing testicular seminoma in a pet rabbit

In the present study, a case of a spontaneously metastasizing seminoma in 9-year-old pet lionhead rabbit is described. The rabbit was presented with unilateral testicular enlargement and a palpable abdominal mass. Spiral computed tomography revealed the presence of an abdominal-pelvic mass in the region of the sublumbar lymph nodes. Testes and lymph nodes were collected, fixed in formalin, and submitted for histopathological examination. Microscopically, the normal architecture of the enlarged testis and lymph node was completely replaced by a diffuse malignant seminoma.

Canine ovarian tumors: an immunohistochemical study with HBME-1 antibody.

The morphology of ovarian tumors is characterized by a variety of histological features causing diagnostic difficulties. In human medicine, HBME-1 (Hector Battifora mesothelial epitope)-1 is one of the immunohistochemical markers employed in the diagnosis of ovarian epithelial tumors. The aim of the current study was to investigate the reliability of the marker HBME-1 in canine ovaries, granulosa cell tumors, and epithelial ovarian neoplasms to determine whether this marker could be included in an immunohistochemical panel for differential diagnoses of canine ovarian tumors. Samples were obtained from 4 normal ovaries, 10 granulosa cell tumors, and 18 epithelial ovarian tumors. After formalin fixation and paraffin embedding, tissue sections were stained with hematoxylin and eosin and probed immunohistochemically for the HBME-1 marker. Granulosa cells and related tumors were consistently negative for HBME-1. Normal ovarian surface epithelium and 17 out of 18 ovarian epithelial tumors were positive for HBME-1. The results suggested that HBME-1 would be a useful marker for the differential diagnosis of ovarian tumors in the dog.

Immunohistochemical expression of SOX9 protein in immature, mature, and neoplastic canine Sertoli cells

Sex-determining region Y box9 gene (SOX9) protein plays a pivotal role in male sexual development. It regulates the transcription of the anti-Müllerian hormone gene promoting development of testis cords, multiplication, and maturation of Sertoli cells (SCs) and maintenance of spermatogenesis in adult testis. The immunohistochemical expression of SOX9 in normal testes has been reported in humans, mice, and rats. The present study aimed to investigate the expression of SOX9 in canine SCs during testicular maturation and neoplastic transformation. Canine testicular samples derived from three fetuses, four newborns, four prepubertal puppies, five adult dogs, 31 Sertoli cell tumors (SCTs) (one metastasizing), and five Leydig cell tumors (LCTs) were selected from departmental archive and tested immunohistochemically with a polyclonal antibody against SOX9 (1:150). All SCs from fetal, neonatal, and adult testes had a strong and exclusively nuclear labeling for SOX9. In SCs from prepubertal testes, SOX9 staining was highly variable with one negative sample (one of four), two samples with exclusively nuclear staining (two of four), and one with both nuclear and cytoplasmic labeling (one of four). Leydig cells (LCs) and LCTs were always negative. All 31 SCTs were positive for SOX9. The expression of SOX9 was nuclear, nuclear and cytoplasmic, and exclusively cytoplasmic in 18 of 31, 11 of 31, and two of 31 SCTs, respectively. This first report on the immunohistochemical expression of SOX9 in canine testes reports that in normal SCs from fetal, neonatal, and adult testes SOX9 labeled the nucleus, as in humans and laboratory animals. The cytoplasmic labeling observed in one prepubertal pairs of testes and in 11 SCTs could reflect SC immaturity or dedifferentiation, paralleling results observed in rat testes. The expression of SOX9 in SCs and SCTs and its absence in LCs and LCTs suggests that SOX9 is a reliable diagnostic marker for both normal and neoplastic SCs.

Immunohistochemical study of mixed germ cell sex cord stromal tumours in 13 canine testes.

Mixed germ cell sex cord stromal tumours (MGSCTs) are composed of seminiferous tubules, filled with admixed neoplastic Sertoli cells (SCs) and germ cells (GCs). The aim of the present study was to describe 13 canine testicular MGSCTs and to investigate the histochemical features and the immunophenotype of the neoplastic GCs and SCs. Neoplastic SCs were always diffusely labelled for vimentin (VIM), neuron specific enolase (NSE), inhibin (INH)-α and anti-Müllerian hormone (AMH). Cytokeratins AE1/AE3 (CK) and desmin (DES) were expressed in 6/13 and 8/13 cases, respectively. Neoplastic GCs were labelled for placental alkaline phosphatase (PLAP) in 7/13 cases and for CD117 (KIT) in 8/13 cases, while 10 cases were stained uniformly by periodic acid-Schiff (PAS). Immature canine SCs are known to express CK, DES, INH-α and AMH, while immature GCs are stained by PAS and express PLAP and KIT. This GC phenotype also distinguishes between classical and spermatocytic seminoma, with the latter being negative for these markers. The results of the present study show that both neoplastic SCs and GCs in MGSCTs have a de-differentiated phenotype.

Testicular XX (SRY-Negative) Disorder of Sex Development in Cat

In most mammals, the sex of an individual is genetically determined by the Y chromosome-specific SRY gene. The presence of at least one functional copy of this gene determines the development of the primordial gonads into testes. However, testicular tissue does develop in the absence of SRY, albeit rarely, which is the case in testicular XX (SRY-negative) disorder of sex development (DSD). This condition is very important for studying the process of sexual determination because it allows the identification of genetic factors that are able to promote the male developmental pathway in the absence of SRY and thereby enables a better understanding of this process. Until now, this condition has been identified in various animal species but has never been reported in cat. In this study, we describe the first case of an XX (SRY-negative) DSD cat. The cat possesses a tortoiseshell coat associated with male-like external genitalia, including normal scrotum with 2 palpably normal testicles. Histological analysis confirmed the presence of the testes, and cytogenetic and genetic analyses showed a female karyotype associated with the absence of the SRY gene. Finally, sequencing of the RSPO1 gene revealed no mutation, and FISH analysis of the SOX9 locus did not reveal any large abnormalities.

Immunohistochemical Expression of Placental Alkaline Phosphatase in Five Cases of Seminoma in Rabbits

Testicular seminoma is reported in the rabbit but data about the immunophenotype of these tumours are lacking. The classification of human testicular germ cell tumours includes spermatocytic tumour (ST) originating from the post-pubertal spermatogonia/spermatocytes, which metastasizes rarely, and seminoma (SE), originating from gonocytes, which is malignant and metastasizes frequently. Gonocytes express placental alkaline phosphatase (PLAP) and are stained with periodic acid-Schiff (PAS). We report five cases of seminoma in pet rabbits. Microscopically, all the cases were diffuse seminoma and in one case there was metastasis to a sublumbar lymph node. Immunohistochemical expression of PLAP was diffuse in this metastatic tumour, in two other cases it was multifocal, in another it was limited to rare cells and in the remaining case was negative. PAS-positive cells were detected only in the four cases that expressed PLAP. These four cases were therefore classified as SE and the tumour without PLAP labelling or PAS staining was defined as ST. Both forms of human germ cell tumour therefore occur in the rabbit. SE appears to be well represented and may show metastasis, paralleling the human counterpart. The results of this study provide a basis for further evaluations of the rabbit as a possible animal model for the study of human SE.