Immunohistochemical expression of p53, fibroblast growth factor-b, and transforming growth factor-alpha in feline vaccine-associated sarcomas

Fifty feline sarcomas associated with vaccine-site injection were evaluated to determine the immunohistochemical expression of p53 protein, basic fibroblast growth factor (FGF-b), and transforming growth factor-alpha (TGF-alpha). Forty-one tumors (82%) were fibrosarcomas (FS), eight (16%) were malignant fibrous histiocytomas (MFH), and one (2%) was a chondrosarcoma (CS). Overexpression of p53 protein was observed in the nuclei of tumor cells in 28 (56%) sarcomas; FGF-b expression was found in the cytoplasm of tumor cells in 40 (80%) feline sarcomas, but the staining was more intense in the spindle-shaped cells of FS than in polygonal or round cells of MFH. The single CS faintly expressed FGF-b. The majority of feline vaccine-associated sarcomas (43 of 50, 86%) expressed moderate or intense staining for TGF-alpha in the cytoplasm of tumor cells. Heterogeneous immunolabeling for p53, FGF-b, and TGF-alpha was present in neoplastic, multinucleated giant cells. Intense expression of FGF-b was statistically associated with younger cats (P < 0.01) and with tumors with nodular growth patterns (P = 0.02). In addition, sarcomas negative for p53 protein expressed FGF-b more frequently than did p53-positive tumors (P = 0.04). The frequency of FGF-b immunostaining was significantly higher in sarcomas with intense expression of TGF-alpha (P = 0.05). Immunohistochemical detection of p53 protein, FGF-b, and TGF-alpha suggests that these growth-regulating proteins may play different roles in the development of sarcomas associated with vaccine sites.     

Fibrosarcomas at presumed sites of injection in dogs: characteristics and comparison with non-vaccination site fibrosarcomas and feline post-vaccinal fibrosarcomas

Fifteen fibrosarcomas, surgically excised from presumed sites of injection in dogs, and 10 canine fibrosarcomas excised from sites not used for injection were histologically and immunohistochemically compared with 20 feline post-vaccinal fibrosarcomas. Canine fibrosarcomas from presumed injection sites were of grade I (3), of grade II (4) and grade III (8). Two fibrosarcomas from non-injection sites were of grade I, four of grade II and four of grade III. Feline samples were classified as grade I (2), grade II (4) and grade III (14). All fibrosarcomas from presumed injection sites of both species showed lymphocytic inflammatory infiltration located at the tumour periphery, while two canine fibrosarcomas from non-injection sites showed perivascular inflammatory infiltration within the neoplasm. All samples were immunohistochemically examined for vimentin, smooth muscle actin, muscle specific actin and desmin expression. All tumours were positive for vimentin. Ten canine fibrosarcomas from presumed injection sites and all feline samples contained cells consistent with a myofibroblastic immunophenotype. Aluminium deposits were detected in eight canine fibrosarcomas from presumed injection sites and 11 feline post-vaccinal fibrosarcomas by the aurintricarboxylic acid method. The present study identifies distinct similarities between canine fibrosarcomas from presumed injection sites and feline post-vaccinal fibrosarcomas, suggesting the possibility of the development of post-injection sarcomas not only in cats, but also in dogs.     

Tail root osteosarcoma in a chipmunk (Tamias sibiricus)

An 8-year-old chipmunk (Tamias sibiricus) showed a mass on the tail root. Histologically, the excised mass showed proliferation of spindle-to-polyhedral cells and abundant multinucleated giant cells, with the production of neoplastic osteoid. Immunohistochemically, neoplastic cells were positive for vimentin and weakly positive for osteocalcin. Osteoid was also positive for osteocalcin. This tumor was diagnosed as a giant cell-type osteosarcoma. This is the first case report of osteosarcoma in a chipmunk.     

Immunohistochemical detection of p53 tumor-suppressor protein is a poor indicator of prognosis for canine cutaneous mast cell tumors

Eighty-three canine cutaneous mast cell tumors were graded histologically and evaluated immunohistochemically for p53 tumor-suppressor protein expression. An avidin-biotin immunohistochemical protocol incorporated a rabbit polyclonal antibody (CM-1) directed against normal and mutant p53 protein. Positive staining was observed in 44.6% (37/83) of tumors and included 50% (12/24) of grade I (well differentiated) tumors, 46.9% (23/49) of grade II (intermediate differentiation) tumors, and 20% (2/10) of grade III (poorly differentiated) tumors. A statistically significantly higher proportion (P < 0.019) of tumors from the head and neck (83.3%, 10/12), stained positive for p53 than tumors from the thorax, back, abdomen, and axilla (39.4%, 13/33), legs (35.7%, 10/28), or prepuce, scrotal, or inguinal areas (44.4%, 4/9). No statistically significant difference between p53 labeling and histologic grade, breed, or tumor size was present. Survival data were available for 53/83 (63.9%) of dogs. Positive reactivity for p53 was observed in 47% (25/53) of tumors within this group, with 57.9% (11/19) of grade I, 43.3% (13/30) of grade II, and 25% (1/4) of grade III tumors labeled. Mean survival time for the 53 dogs was 12.1 months. The median survival time for dogs with grade III tumors or tumors >5 cm was statistically significantly shorter (P < 0.0001) than for dogs with grades I and II or smaller tumors. Although p53 protein abnormalities may play a role in tumor development or behavior in some canine cutaneous mast cell tumors, immunoreactivity was not associated with lack of tumor differentiation, tumor locations previously shown to demonstrate aggressive biological behavior, breed predisposition, or survival times.     

B-cell immunoblastic lymphoma with multinucleated giant cells in a cat

A 10-year-old male mixed breed cat died after six months history of intermittent vomiting and weight loss. At necropsy, large white-colored foci were found in both kidneys, and whitish thickening of the gastric wall was present at the pyloric part of the stomach. Histopathological examination revealed that both lesions consisted of proliferation of large-sized neoplastic lymphocytes intermingled with multinucleated giant cells. Immunohistochemically, the neoplastic cells were positive for both B-cell antigen receptor complex (CD 79 alpha cy) and MHC class II, although multinucleated giant cells were negative. The present case was diagnosed as B-cell immunoblastic lymphoma with multinucleated giant cells.     

Use of s-100 and chromogranin a antibodies as immunohistochemical markers on detection of malignancy in aortic body tumors in dog

To define the characteristics of malignancy we performed routine histology and an immunohistochemical study on seventeen aortic body tumors in dogs. We essayed tumors using a panel of immunohistochemical markers: neuron specific enolase (NSE), chromogranin A (CrA) and S-100. Among 17 cases, the neoplastic cells were positive for NSE (17 cases, 100%), S-100 (9 cases, 53%), and CrA (8 cases, 47%), respectively. The sustentacular cells density and chief cell staining intensity were both inversely related to tumor grade. The most relevant data was consistent with a negative staining of S-100 correlated with absence or decreased number of sustentacular cells in tumors grade III. This report indicates that the immunohistochemical panel has utility for the diagnosis of chemodectoma and the negative staining to CrA and S-100 markers in tumors grade III expresses an indication of malignant behaviour of the tumor.     

Malignant histiocytosis in cattle

Malignant histiocytosis was diagnosed in 4 cows. In all cases the tumor tissues were composed of cytologically atypical histiocytes with evidence of erythrophagocytosis. The tumor in case 1 appeared highly anaplastic with marked nuclear pleomorphism, and had areas of spindle cell differentiation, but had no relation to malignant fibrous histiocytoma. The neoplastic tissue in case 2, characterized by cohesive growth of tumor cells, was distinguishable from anaplastic carcinoma cells by cytokeratin immunostaining. There were many hemosiderin-laden neoplastic cells suggestive of high phagocytic activity in a lymph node of case 3. The neoplastic cells in case 4, frequently multinucleated, were less atypical than in the other cases. All cases expressed histiocyte-associated markers (lysozyme and HAM56), and were negative for cytokeratin, S100, and T- and B-cell lineage-specific markers (CD3 and CD79a). The most frequent HAM56 immunoreactivity was detected in case 4, and the giant, multinucleated forms, reminiscent of epithelioid cell differentiation. seemed not to indicate cytological pleomorphism as a result of neoplastic transformation.     

Proposal of a 2-tier histologic grading system for canine cutaneous mast cell tumors to more accurately predict biological behavior

Currently, prognostic and therapeutic determinations for canine cutaneous mast cell tumors (MCTs) are primarily based on histologic grade. However, the use of different grading systems by veterinary pathologists and institutional modifications make the prognostic value of histologic grading highly questionable. To evaluate the consistency of microscopic grading among veterinary pathologists and the prognostic significance of the Patnaik grading system, 95 cutaneous MCTs from 95 dogs were graded in a blinded study by 28 veterinary pathologists from 16 institutions. Concordance among veterinary pathologists was 75% for the diagnosis of grade 3 MCTs and less than 64% for the diagnosis of grade 1 and 2 MCTs. To improve concordance among pathologists and to provide better prognostic significance, a 2-tier histologic grading system was devised. The diagnosis of high-grade MCTs is based on the presence of any one of the following criteria: at least 7 mitotic figures in 10 high-power fields (hpf); at least 3 multinucleated (3 or more nuclei) cells in 10 hpf; at least 3 bizarre nuclei in 10 hpf; karyomegaly (ie, nuclear diameters of at least 10% of neoplastic cells vary by at least two-fold). Fields with the highest mitotic activity or with the highest degree of anisokaryosis were selected to assess the different parameters. According to the novel grading system, high-grade MCTs were significantly associated with shorter time to metastasis or new tumor development, and with shorter survival time. The median survival time was less than 4 months for high-grade MCTs but more than 2 years for low-grade MCTs.     

Immunohistochemical and clinical evaluation of p53 in canine cutaneous mast cell tumors

One hundred twenty-six cutaneous mast cell tumors obtained by excisional biopsy from 106 dogs were evaluated using immunohistochemical staining for the presence of p53 protein. A standard avidin-biotin immunohistochemical protocol was used incorporating a polyclonal antibody of rabbit origin (CM-1) as the primary antibody. Histopathologic grading of tumors was performed on hemotoxylin and eosin-stained samples. There was a significant difference in the percentage of cells staining positive for p53 for the histopathologic grades (P = 0.0005). Grade III tumors had a significantly greater p53 content than did grade I or II tumors (P < 0.05). Clinical data obtained retrospectively was available for 54 dogs. Tumor recurred in 19 of 54 (35.2%) dogs. Twenty-nine dogs died by the end of the study; 9 of 29 (31.0%) died of mast cell tumor disease. Histopathologic grade showed a significant negative association with survival time. Both clinical stage and histopathologic grade showed a significant negative association with time to recurrence. The percentage of cells staining positive for p53 did not significantly improve the forward analysis. Immunohistochemical detection of p53 did not appear useful in characterizing the clinical association between cutaneous mast cell tumor cellular features and survival time or time to tumor recurrence in dogs.     

Biologic behavior and prognostic factors for mast cell tumors of the canine muzzle: 24 cases (1990-2001)

The medical records of 24 dogs with histologically confirmed mast cell tumors (MCT) of the muzzle were retrospectively evaluated to determine their biologic behavior and prognostic factors. Information on signalment, tumor grade and stage, treatment methods, and pattern of and time to failure and death was obtained from the medical record. Twenty-three dogs were treated with combinations of radiotherapy, surgery, and chemotherapy; 1 dog received no treatment. There were 2 Grade 1, 15 Grade 11, and 7 Grade III tumors. Tumors were stage 0 (n = 8), stage 1 (5), stage 2 (6), stage 3 (4), and stage 4 (1). Mean and median survival times of treated dogs were 36 and 30 months, respectively. Prognostic factors affecting survival time included tumor grade and presence of metastasis at diagnosis. Dogs with Grade I and II tumors survived longer than dogs with Grade III tumors. Variables, including sex, age, gross versus microscopic disease, and treatment type were not found to affect survival. Local control rate was 75% at 1 year and 50% at 3 years. Tumor grade was the only variable found to affect local control. Dogs with Grade I tumors had longer disease-free intervals than those with Grade II tumors, and dogs with Grade II tumors had longer disease-free intervals than dogs with Grade III tumors. Eight of 9 dogs dying of MCT had local or regional disease progression. Muzzle MCT a rebiologically aggressive tumors with higher regional metastatic rates than previously reported for MCT in other sites.     

Giant cell tumour of bone in a cat with extraskeletal metastases: pathological and immunohistochemical study

A case of giant cell tumour of bone (GCTb) in the lung and in a subcutaneous mass located in the right flank, with a probable primary origin in the mid-diaphysis of the right tibia, was described in a 8-year-old female cat. Numerous multinucleated giant cells were homogeneously distributed among a population of ovoid or spindle-shaped mononuclear cells. All of them were positive for vimentin suggesting a mesenchymal origin. Spindle-shaped tumour cells resemble fibroblastic cells, showing collagen fibres in their vicinity. Ovoid mononuclear cells are similar to macrophages, with a cytoplasm rich in electron-dense lysosomes. Multinucleated giant cells appear morphologically similar to osteoclasts. These findings are supported for the positive reaction to tartrate-resistant acid phosphatase (TRAP) and lysozyme, encountered only in ovoid and multinucleated giant cells. No immunoreactivity against human oestrogen receptors was observed in the nuclei of any neoplastic cells.     

Immunohistochemical detection of P-glycoprotein (PGP) and multidrug resistance-associated protein (MRP) in canine cutaneous mast cell tumors

Fifty-four canine cutaneous mast cell tumors were evaluated immunohistochemically for the expression of P-glycoprotein (PGP) and multidrug-resistance-associated protein (MRP). All tumors examined were graded according to the histological malignancy. ranging from grade I to III. The expression of PGP was confirmed in 15% (8/54) of whole, 33% (5/15) of grade I, 10% (3/31) of grade II, and 0% (0/8) of grade III tumors. The expression of MRP was found in 18% (10/54) of whole, 26% (4/15) of grade I, 19% (6/31) of grade II, and 0% (0/8) of grade III tumors. The cases positive to at least one of these 2 multidrug markers were 26%, 47%, 23% and 0% of whole and grade I to III tumors, respectively. These results indicate that at least 26% of canine cutaneous mast cell tumors express PGP and/or MRP and that these tumors may be resistant to several anti-cancer drugs.     

Malignant fibrous histiocytoma (giant cell type) associated with a malignant mixed tumor in the salivary gland of a dog

A 12-year-old male Boxer dog presented with a 5 x 5 x 7-cm partially encapsulated mass in the right mandibular salivary gland. Histologically, the mass was composed of neoplastic epithelial and mesenchymal cells. The mesenchymal component consisted of two cell populations arranged in different patterns: coalescing nodules of neoplastic mononuclear cells with rare osteoid and numerous osteoclastlike giant cells; and sheets of neoplastic spindle cells intermingled with neoplastic epithelial cells and containing osteoid and well-formed bone trabeculae lined by osteoblasts and few osteoclastlike giant cells. On the basis of these histological features, two malignant salivary tumors were diagnosed: a malignant fibrous histiocytoma (giant cell type) and a malignant mixed tumor. Immunohistochemical studies demonstrated keratin 5 and 8 expression by the neoplastic epithelial cells, indicating a probable salivary ductal origin, and vimentin expression by all mesenchymal elements, suggesting a fibroblastic line of differentiation.     

Three cases of canine gastrointestinal stromal tumors with multiple differentiations and c-kit-expression

Three canine gastrointestinal stromal tumors (GISTs) were examined. Histopathologically, the tumor mass in the jejunum (Case 1) consisted of the proliferation of epithelioid cells with abundant eosinophilic or vacuolated cytoplasm. Gangliocyte-like or multinucleated giant cells were scattered. The tumor cells exhibited neural natures mimicking human gastrointestinal autonomic nerve tumors, which were immunopositive for several neuronal markers. Another jejunal mass (Case 2) was composed by a solid proliferation of spindle-shaped cells, arranging in interlacing fascicles and occasional storiform pattern. The tumor seemed to be classified undifferentiated GISTs, that showed no apparent neural or muscular features by ultrastructural and immunohistochemical examinations. In the pyloric mass (Case 3), the spindle cells having eosinophilic processes and elongated nuclei were arranged in sheets. Immunohistochemically, the tumor cells showed muscular natures as regards alpha smooth muscle actin and desmin expression.     

Equine giant cell tumor of soft parts: a series of 21 cases (2000-2007).

In horses, giant-cell tumors of soft parts are rare neoplasms, with the majority of reported cases occurring within the hind limb muscles and soft tissues in older horses. The following article documents 21 cases of equine giant-cell tumors of soft parts clinically examined within the state of Colorado from 2000 to 2007. The majority of cases occurred in male horses aged 10 years or older. Nine (43%) arose within the hind limbs. Key histologic features included numerous multinucleated giant cells and hemosiderin-laden macrophages admixed with a spindle-cell proliferation. The majority demonstrated liposarcomatous change, variable areas of necrosis and hemorrhage, and an intermediate number of mitotic figures. Immunohistochemical results demonstrated 2 distinct cell populations: vimentin-expressing neoplastic mesenchymal cells and CD18 (histiocytic marker) expressing multinucleated giant cells. These results suggest a mesenchymal origin of the neoplasm with possible recruitment of the secondary histiocytic population. Surgical excision was attempted in the majority of horses and was considered clinically complete. A recurrence of the neoplasm was documented in 1 horse and 1 mule. In 18 horses, surgical excision, regardless of margin integrity, appeared successful with no recurrence of disease documented. Unfortunately, 10 of 21 horses were lost to follow-up within approximately 3 months of surgery. Of the 11 remaining horses that were available for follow-up evaluation, there has been no evidence of metastasis. A larger case series with more controlled follow-up is necessary to evaluate malignant potential and the importance of complete surgical excision.     

Prognostic significance of a new histologic grading system for canine osteosarcoma

Histologic grade is an important determinant in clinical outcome of human osteosarcoma (OS). In this study, the histologic characteristics of primary and metastatic canine OS were evaluated using a new classification system. Histologic characteristics were classified in 166 primary and 34 metastatic canine OS. Prognostic variables for clinical outcome were determined using multivariate analysis. Most OS were histologically characterized by severe to extreme cellular pleomorphism, a variable number of mitoses, small to moderate amounts of matrix, a high percentage of tumor cells, and minimal to moderate amounts of necrosis. Tumor invasion into vessels was present in 117/152 (71%) tumors, and 12/50 (24%) of the regional lymph nodes had evidence of metastasis. Classification of the 166 tumors resulted in seven (4%) grade 1, 34 (21%) grade II, and 125 (75%) grade III OS. In the multivariate analysis, histologic grade III OS and elevated pretreatment plasma alkaline phosphatase (AP) levels were independent predictors of clinical outcome. Dogs with high-grade tumors and elevated AP should be carefully evaluated for the presence of metastatic disease before starting adjunctive therapy protocols.     

Spontaneous Extraskeletal Osteosarcoma in a Rabbit (Oryctolagus cuniculus): Histopathological and Immunohistochemical Findings

A spontaneously occurring subcutaneous mass in the left forelimb of a nine-year-old rabbit (Oryctolagus cuniculus) was examined histopathologically and immunohistochemically. Clinically, edema and hemorrhage were seen around the mass. No connection of the tumor mass to the appendicular skeleton was found. The tumor was arranged in a solid growth pattern and irregular bundles, and neoplastic cells were polygonal to spindle-shape. Osteoid (positive for osteocalcin) and multinucleated giant cells were diffusely or focally seen. Neoplastic cells were positive for vimentin, osterix and Ki-67, indicating the nature of osteoblasts with proliferating activity, but negative for α-smooth muscle actin, desmin or CD204. Based on these findings, a diagnosis of extraskeletal osteosarcoma was made, a very rare tumor both in laboratory and pet rabbits.     

Atypical and malignant canine intracranial meningiomas may have lower apparent diffusion coefficient values than benign tumors

Canine intracranial meningiomas can be graded based on histological classification as benign (grade I), atypical (grade II), and anaplastic or malignant (grade III). In people, grade II/III meningiomas behave more aggressively, have a higher potential for recurrence after surgical resection, and have lower apparent diffusion coefficient (ADC) values with diffusion weighted imaging (DWI). In this retrospective analytical cross‐sectional study, 42 dogs had ADC values quantified in an attempt to differentiate tumor histologic grade. Our hypothesis was that ADC values would be significantly lower in grade II and III versus grade I meningiomas in dogs. On each ADC image, a polygonal region of interest (ROI) was hand‐drawn along the lesion's periphery, excluding fluid‐filled and hemorrhagic regions. Mean ADC value (ADC_mean) and minimum ADC value (ADC_min) were calculated. Additionally, two smaller, ovoid ROI were drawn within the lesion with mean ADC calculated (ADC_{mean sR} and ADC_{min sR}). Normalized ADC values using white matter were also calculated (ADC_n and ADC_{n sR}). Grades of each tumor were assigned based on histopathology review. Association between ADC parameters and histological grade was tested by means of two‐sample t‐tests. There were 14 grade I (33.3%), 25 grade II (59.5%), and three grade III (7.2%) meningiomas. ADC_{mean sR} and ADC_{min sR} were significantly lower when comparing grade II/III to grade I (P < .05). Grade II tumors had significantly lower ADC_mean, ADC_{mean sR}, ADC_{min sR}, ADC_n, and ADC_{n sR} than grade I meningiomas. This preliminary study supports the potential of ADC values to help predict the histological grade of intracranial meningiomas in dogs.     

Iridium-192 interstitial brachytherapy as adjunctive treatment for canine cutaneous mast cell tumors

Eleven dogs with cutaneous mast cell tumors (MCTs) were treated with surgery and iridium-192 ((192)Ir) interstitial brachytherapy. Minimum tumor doses ranged from 47.2 to 63.3 Gy. Treated tumors were classified as grade II (n=7) or III (n=4). Five dogs had recurrences with a median progression-free interval of 1391 days, and six dogs had no recurrence at a median follow-up time of 942 days. Acute adverse effects were well tolerated, and late effects were mild. One dog developed a second tumor of a different cell type in the radiation treatment field.