Ovarian Embryonal Carcinoma in a Dog.

A 17-month-old female doberman pinscher was referred for an abdominal mass and ascites. Exploratory laparotomy revealed the presence of a large neoplastic mass replacing the right ovary and associated with multiple mesovarian, mesometrial and peritoneal nodules. An ovariohysterectomy was performed. Grossly, the tumour was soft and multilocular with large areas of haemorrhage and necrosis. Microscopically, it was infiltrative and composed of round and polygonal cells arranged respectively in solid sheets or forming distorted tubular structures separated by thick fibrovascular septae. Tubules contained necrotic debris, proteinaceous fluid or small endoluminal papillary structures. Marked cellular atypia, multiple neoplastic emboli and high mitotic count were observed. Immunohistochemically, the round cells uniformly expressed placental alkaline phosphatase, while the polygonal cells arranged in tubules and papillae expressed cytokeratin (CK) AE1/AE3 and CK7. A final diagnosis of metastasizing ovarian embryonal carcinoma (EC), a primitive germ cell tumour characterized by rudimentary epithelial differentiation was made. Canine ovarian EC should be considered as a differential diagnosis for undifferentiated aggressive ovarian tumours in young dogs.

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.

Immunophenotyping of Rabbit Testicular Germ and Sertoli Cells Across Maturational Stages.

During testicular maturation, both Sertoli cells (SCs) and germ cells (GCs) switch from an immature to a mature immunophenotype. The reexpression of markers of immaturity in adults has been reported in cancer and in other testicular pathologies, in men as well as in animal species. Naturally affected with testicular cancer, rabbits have long been used in human reproductive research, but reports on the expression of testicular cell markers in this species are few and data about the immunophenotype of normal postnatal SCs and GCs are lacking. The aim of this study was to investigate the immunophenotype of SCs and GCs in the rabbit, from neonatal to adult age, using the antibodies anti-Müllerian hormone (AMH), vimentin (VIM), CKAE1/AE3 (cytokeratins [CKs]), desmin (DES), inhibin alpha (INH-α), placental alkaline phosphatase (PLAP), and periodic acid-Schiff (PAS) staining. In SCs, VIM was constantly expressed, and AMH and CKs expression was limited to neonatal and prepubertal age, whereas DES, INH-α, PLAP, and PAS were constantly negative. GCs were negatively stained for PLAP, PAS, and for the other markers. Results revealed analogies with human testicular immunophenotype, suggesting that rabbits could represent a potential experimental model for the study of human testicular pathology.

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.

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.

Carcinocythaemia (carcinoma cell leukaemia) in a dog: an acute leukaemia-like picture due to metastatic carcinoma.

An eight-year-old entire female boxer was presented with a two-week history of anorexia and lethargy and two-day history of unilateral left epistaxis. Clinical findings and laboratory test results suggested disseminated intravascular coagulation. On blood smear evaluation, occasional large epithelioid-like unclassified cells were detected. Occasionally these cells were organised in small clusters. Bone marrow examination revealed a marked infiltration by a malignant population of the same epithelioid-like cells. The dog was euthanased because of the guarded prognosis. Following histology and immunohistochemistry, a widespread undifferentiated carcinoma of unknown primary origin was diagnosed. To the authors' knowledge, this is the first case of carcinoma cell leukaemia reported in a dog. Carcinoma cell leukaemia is a rare oncological condition previously described in humans, characterised by non-haematopoietic neoplastic cells in peripheral blood.

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.

Inhibin-α immunohistochemical expression in mature and immature canine Sertoli and Leydig cells.

Formalin-fixed, paraffin-embedded sections from 32 canine pairs of testes were immunohistochemically examined for Inhibin-α (INHα). Samples were subdivided into two groups (group 1, neonates; group 2, puppies and adults) and results statistically compared. Inhibin-α was significantly expressed only in Sertoli cells of neonatal testes, while in Leydig cells it was expressed without significant difference between groups. These results suggest that, in dogs, INHα expression switches from Sertoli to Leydig cells during testicular maturation and that, in adult, Leydig cells represent the main source of INHα.

Sudden death in a dog after doxorubicin chemotherapy.

A case is reported of fatal cardiomyopathy in an 8-year-old female German Shepherd after standard chemotherapy with doxorubicin for splenic hemangiosarcoma. The main gross lesion was a moderate bilateral cardiac ventricular dilation with diffusely pale myocardium. Histological analysis revealed severe multifocal vacuolar degeneration of cardiomyocytes, myocytolysis, myofibril loss, myocardial fibrosis, and edema. Myocardial fiber vacuolization and myocytolysis were highly suggestive of doxorubicin cardiotoxicity.

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 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.