Malignant histiocytosis with multiple skin lesions in a dog

Doxorubicin for treatment of histiocytic sarcoma in dogs: 31 cases (2003-2017)

OBJECTIVE

To evaluate the efficacy of doxorubicin for treatment of histiocytic sarcoma (HS) in dogs, whether administered as the sole treatment or as an adjunct to surgery or radiation therapy.

ANIMALS

31 client-owned dogs with localized or disseminated HS examined between 2003 and 2017.

PROCEDURES

Medical records were reviewed retrospectively, and data were collected. The Kaplan-Meier method was used to estimate time-to-progression from the date of first doxorubicin administration and survival time from initial diagnosis. Factors that could be associated with poorer outcomes with doxorubicin treatment were analyzed with log-rank tests.

RESULTS

The objective response rate (ORR) was 26%. When stratified by disease status, dogs with localized and disseminated forms experienced 43% and 21% ORRs, respectively. Median time to progression after initiating doxorubicin treatment (n = 30 dogs) was 42 days. Median survival time from initial diagnosis to death (n = 29 dogs) was 169 days. Complete responses were obtained in only 2 dogs that had localized disease and received multimodality therapy.

CLINICAL RELEVANCE

Benefits of doxorubicin administration in canine HS are modest, with a limited ORR and delay in tumor progression, and are comparable to effects attained with other single-agent regimens.

Periarticular histiocytic sarcoma with heart metastasis in a cat

A 4-year-old intact female domestic short-haired cat was referred for recommendations about adjuvant medical treatment 1 month after left forelimb amputation due to periarticular histiocytic sarcoma (HS). At presentation, physical abnormalities were limited to enlarged ipsilateral superficial cervical and axillary lymph nodes. Routine blood analysis, abdominal ultrasound, and thoracic radiology were unremarkable. The cat initially received lomustine without any adverse events. Four weeks later, the cat developed severe acute respiratory distress. Results of thoracic radiographs and transthoracic echocardiographic analysis were suggestive of pulmonary and heart metastasis. Due to the cat's poor clinical condition and prognosis, the owner elected euthanasia, and a necropsy was performed. Based on gross pathology, histopathology, and immunohistochemistry, an HS with nodal, renal, pulmonary, and heart (right auricular and right ventricular) metastases was diagnosed. This case represents the first description of HS with a heart metastasis in a cat, providing further insight into the clinical course and metastatic behavior of this rare malignant neoplasm. Clinicians should be aware of this site of metastasis and consider HS in the list of differential diagnoses for secondary heart tumors in cats.

Cutaneous histiocytic sarcoma with E-cadherin expression in a Pembroke Welsh Corgi dog

An 11-year-old male neutered Pembroke Welsh Corgi dog displayed a mass measuring 7.5 cm × 6.6 cm × 1.6 cm in the skin. Neoplastic tissue was nonencapsulated, and the neoplastic cells showed infiltrative growth into the surrounding tissue on microscopic examination. The neoplastic tissue was mainly located from the dermis to the subcutis. Epidermotropism of neoplastic cells was not observed. The tissue was composed of irregular, solid nests of round to polygonal cells. Nests were separated by fine fibrovascular stroma. Mitotic index was high (7.90 ± 0.38 per high power field) and extensive necrosis was observed in the neoplastic tissue. Vascular invasion was often observed in the neoplastic tissue. Neoplastic cells were positive for vimentin, HLA-DR antigen, Iba1, CD18, and E-cadherin, but cells did not express cytokeratin, S100, CD20, CD79α, CD3, MUM-1, lambda light chain, kappa light chain, lysozyme, CD204, or CD11d by immunohistochemistry. Electron microscopic analysis revealed dendrites on these cells. From the above-mentioned findings, the tumor was diagnosed as a cutaneous histiocytic sarcoma with E-cadherin expression. It is possible that neoplastic cells in the present case were derived from cutaneous Langerhans cell. To our knowledge, cutaneous histiocytic sarcoma with E-cadherin expression in domestic animals has not been previously diagnosed in domestic animals.

Erythrophagocytosis enhances heme-dependent cytotoxicity of antimalarial drugs in canine histiocytic sarcoma cell line DH82

Antimalarial drugs, dihydroartemisinin (DHA) and artesunate (ATS), exhibit iron-dependent cytotoxicity in tumor cells. We hypothesized that erythrophagocytic uptake of heme-iron enhances the cytotoxicity of DHA and ATS. Erythrophagocytic (EP) treatment of the canine histiocytic sarcoma cell line DH82 markedly increased the cytotoxicity of DHA and ATS compared to controls. Succinyl acetone, an inhibitor of intracellular heme synthesis, decreased the cytotoxicity of DHA and ATS in normal cells, but this change was not observed in EP cells. These results suggest that exogenous heme derived from erythrocytes can enhance the cytotoxicity of DHA and ATS. Furthermore, our study suggests that heme could be a novel component of tumor treatment in veterinary medicine.

Establishment and biological characterization of canine histiocytic sarcoma cell lines

Seven novel cell lines from canine histiocytic sarcoma (HS), three of which were disseminated cutaneous HS and four of which were synovial HS, were established. All of the established cell lines had the same morphological (by light and electron microscopic findings), cytochemical (alpha-naphthyl butyrate esterase-positive), and immunohistochemical (vimentin- and lysozyme-positive, and cyto-keratin-negative) characteristics as the original HS tumor cells. All of the established cell lines injected into nude mice subcutaneously produced solid tumors. Because the established cell lines also showed phagocytic and processing activities, the HS tumor cells appear to originate from the mononuclear phagocytic system cells, despite their differences in locations or organs.

Establishment of a new canine cell line (CCT) originated from a cutaneous malignant histiocytosis

A new canine cell line, named CCT, was established from the cutaneous malignant histiocytosis in a 4-year-old male Borzoi. CCT proliferated with loose adherence and doubling time was approximately 30 hr. When co-cultured with latex beads, CCT phagocytized beads vigorously. Lysozyme and vimentin were positive by immunostaining, and non-specific esterase and acid phosphatase were positive by cytochemical staining. These features indicated the cells had a histiocytic nature. Furthermore, by subcutaneous injection to nude mice CCT could successfully form tumors with the morphological and immunohistochemical features similar to the original tumor.

Localized and disseminated histiocytic sarcoma of dendritic cell origin in dogs

Canine histiocytic proliferative disorders include a wide spectrum of diseases characterized by different biologic behaviors. The etiology and pathogenesis of these diseases are largely unknown. The clinicopathologic, morphologic and immunophenotypic characteristics of canine localized and disseminated histiocytic sarcoma were examined in 39 dogs. Rottweilers, Bernese Mountain Dogs, and retrievers were most commonly affected (79%). Localized histiocytic sarcomas (19 dogs) arose from a single site, and metastatic lesions were observed in draining lymph nodes. Predilection sites were subcutis and underlying tissues on extremities, but tumors occurred in other locations, including spleen, lung, brain, nasal cavity, and bone marrow. Disseminated histiocytic sarcomas (20 dogs), a multisystem disease previously described as malignant histiocytosis, primarily affected spleen, lungs, bone marrow, liver, and lymph nodes. Both localized and disseminated canine histiocytic sarcomas were composed of pleomorphic tumor cell populations. CD1+, CD4-, CD11c+, CD11d-, MHC II+, ICAM-1 +, Thy-1 +/- tumor cells were identified in all snap-frozen samples (31 dogs). This phenotype is characteristic for myeloid dendritic antigen-presenting cell lineage. Hence, canine localized and disseminated histiocytic sarcomas are likely myeloid dendritic cell sarcomas. Dendritic antigen-presenting cells are a heterogeneous cell population with regards to their ontogeny, phenotype, function, and localization. The exact sublineage of the proliferating dendritic antigen-presenting cells involved in canine histiocytic sarcomas remains to be determined. Phenotypic analysis of formalin-fixed tissues from eight dogs was limited by available markers. Morphologic features and the phenotype CD18+, CD3-, and CD79a- were the most useful criteria to indicate likely histiocytic origin.

Inheritance of histiocytosis in Bernese mountain dogs

One hundred and twenty-seven cases of histiocytosis in Bernese mountain dogs (BMD) were evaluated to determine if the tumour is inherited. Family data ruled out autosomal recessive, autosomal dominant and sex-linked modes of inheritance. The trait was determined to be inherited with a polygenic mode of inheritance. The salient points permitting this conclusion are: pedigrees developed from independently selected propositi link up allowing the tracing of all cases through several generations; multiple cases occur in the same litter; multiple cases have been produced by given dams and sires; there is a higher frequency of the disease among offspring of affected parents when compared to offspring of normal parents that produced histiocytosis and all offspring in the general population of BMDs; the fact that histiocytosis is common in BMDs and rare in eight other breeds and accounts for 25.4 per cent of the 500 tumours studied in this breed. The heritability of this trait was calculated to be 0.298.