Retrospective study of melanocytic neoplasms in dogs and cats

Melanoma is one of the most lethal skin neoplasms among dogs and cats, and its incidence is increasing worldwide in the last years. The relation between the study of tumor biology and epidemiologic data from melanocytic tumors (melanomas and melanocytomas) can help in the achievement of an earlier and safer clinical diagnosis.However, epidemiologic data for these neoplasms are still rare in Brazil. Thus, we performed a retrospective study of melanocytic neoplasms in dogs and cats registered at the Animal Pathology Service of the School of Veterinary Medicine and Animal Science (SVMAS), University of São Paulo (USP), between January of 2000 and December of 2006. The epidemiological data extracted from pathology records regarded affected population (age, gender, hair color) and tumor characteristics (anatomic location and histological type). Of 2154 histopathological reports analyzed 193 (8.9%) were melanocytic neoplasms, of which 186 cases in dogs (96.4%) and only 7 in cats (3.6%). Male dogs, of

mixed breed, among 8 and 11 years of age and black hair were most affected by melanocytic neoplasms. Histological types most often found were epithelioid cell melanoma mainly located in the buccal cavity, and melanocytomas, located on the skin. Among cats, females between 8 and 11 years of age of mixed breed and black hair were most often affected. Epithelioid melanoma again presented as the most common histological type, located, however, on the skin. In conclusion, this casuistic demonstrated that melanocytic neoplasms develop mostly in middle age dogs with dark hair, in the oral cavity or skin, with histological type of epithelioid cells. Melanocytic tumors are rare in cats when compared to dogs; in our cases, they were diagnosed in middle aged female cats, mostly located in skin, and with epithelioid histological type. Epidemiological data strengthen the importance of early diagnosis of melanocytic tumors in Veterinary Medicine, promoting initiation of the most appropriate therapeutical process, improving diagnosis and promoting animal welfare.

Retrospective study of melanocytic neoplasms in dogs and cats

Melanoma is one of the most lethal skin neoplasms among dogs and cats, and its incidence is increasing worldwide in the last years. The relation between the study of tumor biology and epidemiologic data from melanocytic tumors (melanomas and melanocytomas) can help in the achievement of an earlier and safer clinical diagnosis.However, epidemiologic data for these neoplasms are still rare in Brazil. Thus, we performed a retrospective study of melanocytic neoplasms in dogs and cats registered at the Animal Pathology Service of the School of Veterinary Medicine and Animal Science (SVMAS), University of São Paulo (USP), between January of 2000 and December of 2006. The epidemiological data extracted from pathology records regarded affected population (age, gender, hair color) and tumor characteristics (anatomic location and histological type). Of 2154 histopathological reports analyzed 193 (8.9%) were melanocytic neoplasms, of which 186 cases in dogs (96.4%) and only 7 in cats (3.6%). Male dogs, of

mixed breed, among 8 and 11 years of age and black hair were most affected by melanocytic neoplasms. Histological types most often found were epithelioid cell melanoma mainly located in the buccal cavity, and melanocytomas, located on the skin. Among cats, females between 8 and 11 years of age of mixed breed and black hair were most often affected. Epithelioid melanoma again presented as the most common histological type, located, however, on the skin. In conclusion, this casuistic demonstrated that melanocytic neoplasms develop mostly in middle age dogs with dark hair, in the oral cavity or skin, with histological type of epithelioid cells. Melanocytic tumors are rare in cats when compared to dogs; in our cases, they were diagnosed in middle aged female cats, mostly located in skin, and with epithelioid histological type. Epidemiological data strengthen the importance of early diagnosis of melanocytic tumors in Veterinary Medicine, promoting initiation of the most appropriate therapeutical process, improving diagnosis and promoting animal welfare.(AU)

Canine hemangiopericytomas: cell proliferation and apoptosis in the perivascular, storiform and epithelioid histological subtypes and their significance for prognosis

Canine hemangiopericytomas (CHP) are soft tissue neoplasms, originary from pericytes. They are frequently diagnosed in dogs and can be seen more frequently in limbs as circumscribed and firm nodules. The histopathology of CHP reveals the presence of spindle cells around blood vessels, forming whorls. In this study, cases of CHP from the Animal Pathology Service of the Veterinary Hospital of the School of Veterinary Medicine and Animal Science, registered from 1990 to 2003, were studied. All cases were reviewed and classified in the three histological subtypes recently described - perivascular (PVHP), storiform (SHP) and epithelioid (EHP). Immunohistochemical markers (vimentin, S-100 protein, CD34, Factor VIII and glial fibrillary acidic protein - GFAP) were applied to all tumors. Samples were submitted to the immunostaining of PCNA, and the labeling indexes were obtained. The mitotic index was also quantified in each subtype. Apoptosis bodies were morphologically identified in H&E stained sections, subsequently confirmed by fluorescence microscopy and then quantified in the three histological subtypes. Dog owners were contacted by telephone, and asked to inform about the outcome of their dogs. The survey revealed 61 cases of CHP, in which 21 (34.43.%) belonged to the perivascular subtype, 18 cases (29.51.%) belonged to the storiform subtype, and 22 cases (36.06.%) belonged to the epithelioid subtype. PCNA labeling index, mitotic and apoptotic indexes were significantly higher in the epithelioid subtype. Records of the follow-up of each case revealed 59% of recurrence rate in the epithelioid subtype, 55% in the storiform subtype and 17% in the perivascular subtype. According to these results, epithelioid hemangiopericytomas seem to be the most aggressive CHP subtype. Therefore, we conclude that the histopathological analysis with classification in subtypes, as well as the quantification of cell proliferation and apoptosis rates, can help in the establishment of prognosis for CHP.

Compensatory kidney hypertrophy/hyperplasia after nephrectomy in mice: alterations of connexin 43 (Cx43) phosphorylated isoforms

Compensatory kidney hypertrophy/hyperplasia leads to several changes in kidney structure and function, as increased glomeruli filtration. The aim of this study was to evaluate connexin 43 in remnant mouse kidneys after unilateral nephrectomy. The right kidney was surgically removed from BALB/c mice. Groups were euthanized at 24, 48 and 72 hours, and at 7 and 30 days. Kidney sections of the reminiscent kidneys were stained with Periodic Acid/Schiff and additional slides were submitted to BrdU and Cx43 immunohistochemistry. The results demonstrated an increase in kidney weight as early as 24 hours through 30 post-nephrectomy. In addition, BrdU positive epithelial cells increased at 24 and 48 hours post-nephrectomy. Cx43 was detected in the cytoplasm and membrane of epithelial cells and vasculature. Taking into consideration the quantity, intensity and localization of Cx43 immunostaining pattern, we observed that nephrectomized mice presented lower Cx43 expression and a cytoplasmic localization after 24 hours, peaking in 48 hours. Furthermore, western blot revealed that during the first 24 and 48 hours after nephrectomy, PO (unphosphorylated) and P1 (phosphorylated) Cx43 disappeared, and the products of Cx43 degradation were reduced. On the other hand, after 72 hours the PO and P1 state reappeared and the amount of degraded peptides also increased. Seven and thirty days after nephrectomy, a higher intensity of PO and P1 state and a lower P2 (hyperphosphorylated) band were observed. In conclusion, our results suggest that Cx43 phosphorylation results in the retention of Cx43 in cytoplasm and its increased degradation during compensatory renal hyperplasia/hypertrophy.