Canine Cutaneous Histiocytoma Research Articles

Regression of Canine Cutaneous Histiocytoma is Associated with an Orchestrated Expression of Matrix Metalloproteinases

Canine cutaneous histiocytoma (CCH) is a common benign skin tumour originating from epidermal Langerhans cells. These tumours often display spontaneous regression and therefore represent a valuable animal model for investigation of tumour regression. Based on previous studies it was hypothesized that up-regulation of cytokines during CCH regression leads to up-regulation of matrix metalloproteinases (MMPs) favouring infiltration of lymphocytes and enhanced tumour regression. The expression of MMPs and their inhibitors (tissue inhibitors of metalloproteinases, TIMPs) was investigated immunohistochemically in 27 CCHs. The tumours were classified into four groups defined as having no regression (group 1), early regression (group 2), intermediate regression (group 3) or late regression (group 4). The distribution and expression intensity of MMP-1, -2, -3, -7, -9, -13 and -14 and TIMP-1 and -2 were determined in peripheral and central areas of each tumour. Group 3 and 4 CCHs showed up-regulation of expression of MMP-1, -9 and -14 at the periphery. Variable expression of MMP-2 and -3 was observed. Expression of the remaining MMPs and TIMPs showed no group-specific changes. Most MMPs and TIMPs displayed significantly higher expression at the tumour periphery compared with the centre, independently of the stage of regression and indicating more pronounced proteolysis in the peripheral areas. The results are consistent with cytokine-enhanced MMP expression, particularly of MMP-9, leading to enhanced lymphocyte recruitment in combination with elevated cleavage of extracellular matrix and basement membranes.

犬颈下皮肤组织细胞瘤1例

报告1例犬颈下皮肤组织细胞瘤病例。患病动物为7岁雄性斗牛犬，发现颈下皮肤包块一个多月后送医就诊。经手术切除肿块后固定送检，常规H&E染色后，组织学检查结果发现肿块内有大量肿瘤细胞成分，多为成纤维样细胞和组织细胞样细胞，部分肿瘤细胞团块间散在分布有充满血液的窦状腔隙，但是无内皮细胞包围，某些肿瘤细胞内有含铁血黄素沉积。诊断为皮肤组织细胞瘤。 A case of canine cutaneous histiocytoma under neck skin is reported. A 7-year-old male bulldog was present- ed with a firm subcutaneous nodule under neck skin for more than 1 month. Histopathological examination showed masses of tumor cells consisting of fibroblast- and histiocyte-like cells containing haemosiderin, and there were multi- focal areas of irregular cavities in the masses full of red cells without endothelial lining. These findings were consistent with all histiocytoma.

Cutaneous Mast Cell Tumor With Epitheliotropism in 3 Dogs

Epitheliotropism is an important diagnostic feature of cutaneous epitheliotropic lymphoma and canine cutaneous histiocytoma; however, although noted in certain feline mastocytic diseases, it has not been considered a feature of canine cutaneous mast cell tumor. In this study, 3 canine cutaneous mast cell tumors had epitheliotropic invasion of neoplastic mast cells into the epidermis and follicular epithelium. This unusual histologic finding was characterized by infiltrates of individual and clusters of neoplastic mast cells in the stratum basale and stratum spinosum. The mast cell origin of these cells was documented by demonstration of metachromasia with Giemsa stain and positive immunoreactivity to KIT protein. On the basis of these findings, mast cell tumors should be included in the differential diagnosis for canine cutaneous round cell neoplasms that infiltrate the epidermis.

Immunohistochemical Expression of E-cadherin Does Not Distinguish Canine Cutaneous Histiocytoma From Other Canine Round Cell Tumors

Immunohistochemistry for E-cadherin (ECAD) has been used to distinguish canine cutaneous histiocytoma from other leukocytic neoplasms ("round cell tumors"). To determine the specificity of this test, 5 types of canine cutaneous round cell tumors were evaluated for immunohistochemical expression of ECAD. Tumors of all 5 types had variable cytoplasmic, plasma membrane, and/or paranuclear ECAD expression: All 13 cutaneous histiocytomas were ECAD+; all but 1 of 14 mast cell tumors expressed ECAD; 10 of 12 epitheliotropic lymphomas reacted with E-cadherin antibody; of 72 plasmacytomas, 54 were ECAD+; and 5 of 5 histiocytic sarcomas were positive. Conclusions based on these results include the following: First, immunoreactivity for ECAD is not limited to leukocytes of cutaneous histiocytoma; second, antibody to ECAD also labels neoplastic cells in most mast cell tumors, plasmacytomas, cutaneous histiocytic sarcomas, and epitheliotropic lymphomas; third, although most histiocytomas have membranous ECAD expression, the immunoreactivity varies among round cell tumors and is frequently concurrent in different cellular compartments; fourth, the distinctively paranuclear ECAD expression pattern in epitheliotropic lymphomas might distinguish them from other round cell tumors; and, fifth, ECAD should be used with other markers (eg, MUM1 for plasmacytomas, KIT for mast cell tumors, CD3 and CD79a for lymphomas) to distinguish among canine round cell tumors.

Canine paediatric oncology: retrospective assessment of 9522 tumours in dogs up to 12 months (1993-2008)

Little information is available on the occurrence of neoplasms in dogs up to the age of 12 months. This is a retrospective review of histopathological diagnoses of neoplasia in dogs up to the age of 12 months based on biopsy specimens submitted to a commercial veterinary diagnostic laboratory in the United Kingdom between 1993 and 2008. In 20 280 histological submissions, 9522 neoplasms were identified. Canine cutaneous histiocytoma (n = 8465; 89%) was the most common histological type. Neoplasms other than histiocytoma (n = 1057; 11%) were grouped as benign epithelial (n = 375; 4%), haematopoietic (n = 229; 2%), benign mesenchymal (n = 145; 2%), miscellaneous (n = 118; 1%), non-hematopoietic malignant mesenchymal (n = 118; 1%) or malignant epithelial tumours (n = 72; <1%). Excluding canine cutaneous histiocytoma, 52% of tumours (n = 547) were benign, and 66% were from the skin or soft tissues. These data provide valuable epidemiological information on neoplasms occurring in juvenile dogs in the United Kingdom.

E‐cadherin expression in canine cutaneous histiocytoma

E‐cadherin expression in canine cutaneous histiocytoma

E-cadherin expression in canine cutaneous histiocytomas

Canine cutaneous histiocytoma is a common skin tumour of Langerhans cell origin. Langerhans cells are members of the dendritic cell family of antigen-presenting cells and are located in the epidermis....

CCH cells are potent stimulators in the allogeneic mixed leucocyte reaction

Canine cutaneous histiocytoma (CCH) has been identified as a tumour of epidermal Langerhans cells (LCs) on the basis of immunophenotypic studies. Neoplastic Langerhans cells (CCH-LCs) were isolated from lesions of canine cutaneous histiocytoma. The CCH-LC cells expressed CD1b, CD11/18, CD45, MHC-I, and MHC-II. The CCH-LC cells were potent stimulators of the mixed leucocyte reaction (MLR) in vitro when compared to PBMCs from the tumour-bearing animals. This provides evidence that the neoplastic cells in CCH have functional as well as immunophenotypic characteristics of Langerhans cells.

Korrelation zwischen zytologischen und histologischen Haut-, Lymphknoten- und Milzbefunden bei 500 Hunden und Katzen

The results of 382 cytological examinations in dogs and 118 in cats were retrospectively compared with the correlating histological results.The histological diagnosis represented the gold standard. The investigation comprised skin, lymph node and spleen samples. The aim was to estimate the diagnostic value and the limits of cytological examinations in relation to the type of the changes. The cases were grouped in six categories: Corresponding diagnoses were formulated in 201 cases. In lymph node samples, they were reached almost twice as frequently than in skin and spleen samples. Round cell neoplasias (mast cell tumours, canine cutaneous histiocytomas and malignant lymphomas) were most often subclassified. Cytological diagnoses lacking subclassification were reached in 98 cases. The lesions were cytologically less precisely characterized than histologically. Provisional cytological diagnosis or differential diagnosis were formulated in 112 cases. Most commonly, the distinction between neoplastic and non-neoplastic character of a lesion was not possible (especially in mesenchymal spindle-cell proliferations). In 53 cases, the cytological diagnosis could not be established. In 22 cases, the relevant lesion was diagnosed only histologically whereas the cytological picture revealed another, usually secondary tissue reaction. Cytologically incorrect diagnoses were formulated in 14 cases.

The regression of a canine Langerhans cell tumour is associated with increased expression of IL-2, TNF-alpha, IFN-gamma and iNOS mRNA.

Canine cutaneous histiocytoma is a benign epidermal neoplasm of Langerhans cell origin, which usually displays spontaneous regression. Based on the degree of lymphocytic infiltration, 30 histiocytomas were classified into four groups representing different stages of tumour regression. To elucidate further the mechanisms of the antitumour immune response CD3+, CD21+, CD4+, CD8+ and myeloid/histiocyte antigen+ inflammatory cells were differentiated by immunohistochemistry and quantified. In addition, the number of apoptotic cells was detected using the TdT-mediated biotin-dUTP nick-end labelling (TUNEL) method. Furthermore, the expression of interleukin- (IL-2), IL-12(p40), tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), IL-10 and transforming growth factor-beta (TGF-beta) as well as inducible nitric oxid synthase (iNOS) mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR). Phenotyping of inflammatory cells revealed a significantly increased infiltration of all lymphocyte subsets and myeloid/histiocytic cells with the onset of tumour regression. The latter was significantly correlated to up-regulation of IL-2, TNF-alpha, IFN-gamma and iNOS mRNA expression. Expression of remaining cytokines and percentage of apoptotic cells showed no group-specific changes. The results indicate an initial infiltration of CD4+ T cells followed by increased expression of Th1 cytokines and recruitment of antitumour effector cells as the principal mechanism for tumour regression. Canine cutaneous histiocytoma is a unique example for an effective immune response in a naturally occurring neoplasm derived from epidermal Langerhans cells and might represent a valuable animal model to investigate tumour immunity.

Clinical and Pathological Studies of Canine Cutaneous Histiocytomas

Clinical and Pathological Studies of Canine Cutaneous Histiocytomas

Immunohistochemical and Histochemical Stains for Differentiating Canine Cutaneous Round Cell Tumors

Immunohistochemical and histochemical stains are useful adjunct techniques in the diagnosis of canine cutaneous round cell tumors, which can appear histologically similar. We applied a panel of monoclonal antibodies (recognizing tryptase, chymase, serotonin for mast cells; CD1a, CD18, MHC class II for histiocytes; CD3 for T lymphocytes; CD79a for B lymphocytes and plasma cells) and one histochemical stain (naphthol AS-D chloroacetate for chymase activity) to formalin-fixed, paraffin-embedded sections of canine cutaneous mast cell tumors, histiocytomas, lymphosarcomas, plasmacytomas, and unidentified round cell tumors. Of 21 tumors with a histologic diagnosis of mast cell tumor, 7/7 (100%) grade I, 6/7 (85.7%) grade II, and 3/7 (42.9%) grade III tumors were diagnosed as mast cell tumors based on positive staining for tryptase antigen and chymase activity. Mast cells were positive for both tryptase antigen and chymase activity, indicating equal efficacy of tryptase immunohistochemistry and chymase histochemistry. Chymase was detected immunohistochemically in both tumor and nontumor cells, while serotonin was not detected in most mast cell tumors, and thus, neither was useful in the diagnosis of mast cell tumors. Immunohistochemistry to detect CD18 and MHC class II was equally effective in staining histiocytomas, although lymphosarcoma must be ruled out through the use of CD3 and CD79a immunohistochemistry. Immunohistochemistry using three different monoclonal antibodies to human CD1a showed no cross-reactivity in canine histiocytomas and was not useful. A final diagnosis was obtained for 4/5 (80%) of the unidentified tumors, indicating the usefulness of multiple stains in poorly differentiated round cell tumors.

FC‐28 Ultrastructural markers expressed in cultured canine dendritic cells and laminated bodies found in Langerhans cells: similarities and differences

Ultrastructural markers that consist of coated vesicles, regularly laminated bodies, pleiomorphic inclusions and paracrystalline structures have been described in canine cutaneous histiocytoma (CCH), a cutaneous tumour of Langerhans cell origin. These microstructures are also observed in congenital self‐healing histiocytosis, a human Langerhans cell tumour. We have observed for the first time ultrastructural markers in canine dendritic cells (DC) that share some of the features of the microstructures described in CCH. Canine DC were generated in vitro from adherent peripheral blood mononuclear cells. Morphological analyses and ultrastructural and functional studies showed that these cells display typical DC features. After 1 week of in vitro culture of adherent peripheral blood mononuclear cells in the presence of canine IL‐4 and human GM‐CSF, a great proportion of the cells displayed typical cytoplasmic processes (optical and electronic microscopy) and expressed CD14 and MHC class II molecules (cytometric analysis). In addition, allogeneic mixed lymphocyte reactions were performed to assess the ability of these cells to stimulate the proliferation of allogeneic lymphocytes. Compared to monocytes/macrophages, these cells were able to stimulate allogeneic lymphocyte proliferation very strongly, as is reported for DC in other species. Ultrastructural analysis of these DC revealed the presence of cytoplasmic organites, dense granules of variable sizes containing periodic microstructures. These results were obtained for the three different breeds tested. The microstructures previously described in Langerhans cells (e.g. in CCH) share some similarities with periodic microstructures (membrane, laminated aspect, cytoplasmic localization), but not the typical periodic aspect seen in DC. Funding: National Veterinary School of Nantes.

P‐65 Canine cutaneous histiocytoma: morphology and morphometry

Canine cutaneous histiocytoma is a common tumor of young dogs. Nodules are single or multiple, alopecic and well demarcated. We studied 15 young dogs with cutaneous histiocytoma. Cutaneous nodules were cytologically and histologically investigated using routine techniques. The subject for morphometry was the nuclear area of histiocytes. The figures were statistically interpreted (Student's t‐test). Cytologically, histiocytes represented the largest population, being large‐sized cells. The nucleus:cytoplasm ratio was large with oval or bean‐shaped nuclei and a fine arrangement of chromatin. The cytoplasm was discrete and basophilic, or abundant and foamy. Five regressive stages were histologically described. Stage 1 was represented by dermal and hypodermal histiocyte proliferation, covered by an intact, uninfiltrated and atrophic epidermis. Epidermal ulcers and necrotizing foci with neutrophilic, lymphocytic and plasma cell infiltrations occurred in Stages 2, 3 and 4. Stage 5 looked like a chronic dermatitis. In Stage 1, the nuclear area was the smallest (4615 ± 62 pixels) with a small coefficient of variation (14.28%), proving a homogeneous population. Stage 2 histiocytes had a larger and more heterogeneous nuclear area (6116 ± 130 pixels) with a 21.12% coefficient of variation. In Stage 3, the average nuclear area (6431 ± 115 pixels) was larger than that for Stage 2 and had a 19.18% coefficient of variation. There were no significant differences between the nuclear areas of histiocytes from Stages 2 and 3; however, significant differences occurred between Stages 1 and 2, and between Stages 1 and 3. Funding: Self‐funded.

P‐63. Canine cutaneous mastocytoma: correlation between histological grading, cytological nuclear area and nucleus:cytoplasm ratio

Cutaneous mastocytoma is frequently diagnosed in dogs, representing 9–21% of skin tumors. Due to the unpredictable behavior of the tumor, a majority of clinicians consider it dangerous, with a 50% rate of recurrence and 50% of tumors being malignant. Seventeen dogs of various breeds were diagnosed with mastocytoma, inflammation rich in mast cells and tumors infiltrated with mast cells (canine cutaneous histiocytoma). Fine needle biopsies were performed, and smears were stained with May–Grunwald–Giemsa. Histological sections were stained with trichromic Masson and Luna stains. Nuclear areas and nucleus:cytoplasm ratios were determined using computed morphometry. Measurements were made only from smears. The values were statistically interpreted using Student's t‐test. According to histological features, four morphological grades were established: Grade 1 (well differentiated), Grades 2 and 3 (intermediary) and Grade 4 (anaplastic). Nuclear area values ranged from 5147 (±427) to 5847 (±169) pixels in Grade 1 mastocytoma, 4563 (±318) to 6619 (±289) pixels in Grades 2 and 3, and 6864 (±257) to 10456 (±773) pixels in Grade 4. Nucleus:cytoplasm ratios were between 0.37 and 0.44 (mean 0.40) in Grade 1, between 0.42 and 0.43 (mean 0.42) in Grades 2 and 3, and between 0.37 – 0.56 (mean 0.46) in Grade 4. Normal mast cells have a nucleus:cytoplasm ratio of 0.27. The variability of nuclear area values does not allow correlation with the histological grading of mastocytomas; therefore, prognosis cannot be estimated by nuclear area values. The average nucleus:cytoplasm ratio increased from Grade 1 through Grade 4 and correlated with the histological grading of canine mastocytomas. Funding: Self‐funded

イヌ皮膚組織球腫の病理組織学的検索

イヌ皮膚組織球腫の病理組織学的検索

Mitosis and apoptosis in canine cutaneous histiocytoma and transmissible venereal tumour.

Cell proliferation and apoptosis in canine cutaneous histiocytomas and transmissible venereal tumours were examined in twenty cases. The Ki-67 immunohistochemistry and Tunel methods were used to detect mitotic activity and apoptosis, respectively. The number of Ki-67 immunoreactive cells was 11.65 (+/- 1.1706) in canine cutaneous histiocytomas and 17 (+/- 2.1751) in transmissible venereal tumours. The mean values of apoptotic cells for canine cutaneous histiocytomas and transmissible venereal tumours were 13.25 (+/- 1.8758) and 8.52 (+/- 1.1007), respectively. It was considered that mitotic activity and apoptotic indices were useful in differentiation of canine cutaneous histiocytomas and transmissible venereal tumours. The correlation values for canine cutaneous histiocytomas and transmissible venereal tumours were 0.359 (+/- 0.330) and -0.232 (+/- 0.344), respectively. No significant (P > 0.05) correlation was found between mitosis and apoptosis in these two tumour types.

Canine neoplasia in the UK: estimates of incidence rates from a population of insured dogs.

Neoplasia is common in pet dogs but accurate figures for the incidence of tumours in this, as in other species, are sparse. The purpose of this study was to document the occurrence of tumours in a defined population of dogs. From a database of 130,684 insured dogs, claims relating to the investigation or treatment of tumours or tumour-like lesions during a 12-month period were accessed and followed up. A total of 2,546 claims were tumour related and were classified according to tumour site and type. Because the demographics of the insured population were skewed towards younger animals, a standard population, as described in the veterinary literature, was used in the calculation of tumour incidence rates. The skin and soft tissues were the most common sites for tumour development, with a standardised incidence rate of 1,437 per 100,000 dogs per year, followed by alimentary (210), mammary (205), urogenital (139), lymphoid (134), endocrine (113) and oropharyngeal (112). Canine cutaneous histiocytoma was the most common single tumour type, with a standardised incidence rate of 337 per 100,000 dogs per year, followed by lipoma (318), adenoma (175), soft tissue sarcoma (142), mast cell tumour (129) and lymphosarcoma (114). These data are unique and provide a valuable basis for future research into the aetiology and epidemiology of canine tumours.

Progressive Langerhans’ cell histiocytosis in a puppy

A 8‐month‐old, female miniature Dachshund dog was presented for the complaint of pruritic, generalized, multiple nodules and plaques. Two months previously, a nodule on the left pinna was excised and diagnosed as a cutaneous histiocytoma. One month post‐excision, a nodule reappeared at the same site and, shortly thereafter, additional nodules developed. Histopathological examination revealed a diffuse proliferation of histiocytic cells, which reacted strongly to antibodies for vimentin and lysozyme. Immunophenotypic analysis showed that most of the cells expressed CD1a, CD1c, CD11c, CD18, CD45 and MHC class II markers. Electron microscopic examination revealed cytoplasmic filopodia and paracrystalline structures. These findings indicated that the cells originated from Langerhans’ cell. The disease progressed despite glucocorticoid therapy and griseofulvin was administered as an immunomodulating drug. All lesions resolved completely after 7 weeks of griseofulvin treatment. The dog, however, died three months later after discontinuation of griseofulvin therapy and a necropsy was not performed. It is considered that the present canine dermatosis corresponds with a severe form of Langerhans’ cell histiocytosis in humans rather than canine cutaneous histiocytoma.

Editorial

Unusually, in this issue we publish four papers dealing with round cell tumours. Two are concerned with lymphoma1,2 (in cattle and a dog) and two with histiocytic cells3,4 (in a dog and a cat). In the past, the classification of these tumours would have been difficult. Now that markers are available to demonstrate the immunophenotype of the tumour cells, classification has become easier, at least for those with access to more sophisticated laboratories. Even so, classification remains a problem, not only in the veterinary field but also in human medicine. This is particularly true for the histiocytic tumours, which can be reactive or malignant, a difference that is often difficult to determine. An indication of the importance of histiocytic disorders in veterinary dermatology was the selection of this topic as the state of the art address in a main theme at the Fourth World Congress of Veterinary Dermatology, dealing with Dysplasia and Neoplasia. Dr Verena Affolter reviewed the current knowledge of histiocytic cells (monocytes, macrophages and dendritic cells), which are believed to arise from a common CD34 + precursor.5 In the same session, Baines et al. described the maturation states of cells in canine cutaneous histiocytoma by immunophenotyping cells from excised tumours using flow cytometry.6 They showed that the clinical stages of the tumours were characterized by neoplastic Langerhans’ cells at different stages of maturation. The stages present during progression and regression reflected the natural life cycle of normal Langerhans’ cells. The September issue of the British Journal of Dermatology also contained two interesting cases of histiocytic disease. The editorial in that issue reviewed the current state of knowledge in the human field of the histiocytoses.7 These diseases were reclassified in 1997 into three groups:1 Langerhans’ cell histiocytosis,2 Non-Langerhans’ cell histiocytoses, and3 Malignant histiocytoses.8 The group 2 histiocytoses present special difficulty as they involve dermal dendrocytes, a poorly understood group of factor XIIIa positive cells in which derivation from CD34 + bone marrow precursors is as yet unproven. The class 2 tumours include a variety of different clinical entities and Chu7 proposes that their clinical presentations are determined by the level of maturation of the dendrocytes involved. He suggests that the more mature cells are associated with more severe syndromes that are less responsive to treatment. It is clear that, even though immunophenotyping enables us to define the cells involved in histiocytic tumours, there is a great deal still to be learned. As is so often the case, as we learn more so we recognize how little we really understand. This is my last Editorial as Editor-in-Chief and I take the opportunity to pay credit to the many colleagues who have made the job such a pleasure for me. Special thanks are due to my co-editors, Karen Moriello and Ross Bond, who have the responsibility for receiving submissions, arranging for their review, communicating with authors and preparing accepted papers for publication. This is no small task and the quality of Veterinary Dermatology depends to a great extent on their dedication. I wish also to thank the Editorial Board and the Journal Development Advisory Chairs, Richard Anderson and Richard Harvey, who provide continuing support and advice to the editorial team, and to our translators who enable us to publish abstracts in French, German and Spanish. Finally, I would like to thank our publishers, Blackwell Science, who are lovely people to work with. Our new Editor-in-chief is Ian Mason. Ian is a former European co-editor and has a profound knowledge of all aspects of the Journal. I know that in his hands it will prosper. Thank you for taking on the job, Ian. Over to you! D. H. Lloyd