Multifocal cutaneous histiocytic sarcoma in a young dog and review of histiocytic cell immunophenotyping

Abstract

A 9-month-old male Great Dane had progressive generalized nodular dermatopathy for several months. There were > 100 raised, alopecic, firm, painful nodules throughout the skin. Aspirates from several lesions yielded moderate numbers of irregularly round or polygonal to spindle-shaped cells with mild to moderate anisocytosis and few inflammatory cells, and the cytologic interpretation was proliferation of mesenchymal or histiocytic cells. On histopathologic examination, nodules were composed of densely packed sheets of round to spindle-shaped cells with mild anisokaryosis and low mitotic activity. Multifocal histiocytic sarcoma with a spindle-cell pattern was diagnosed based on morphologic features and intense expression of CD18. Additional immunophenotypic analysis on frozen sections of tissue confirmed the diagnosis of histiocytic sarcoma; expression of CD18, CD45, CD1a, CD11b, and CD11c, limited expression of Thy-1 (CD90) and CD80, and lack of expression of CD4, CD11d, and CD86 indicated that the cells were likely interstitial dendritic cells; a review of reactive and neoplastic dendritic cells is provided. Based on staging, internal organs were not affected. Sequential treatment with lomustine and doxorubicin failed to prevent progression of the cutaneous lesions, and the dog died 3 months after initial diagnosis. At necropsy, a focus of neoplastic cells was present in one lymph node, but except for skin other organs were not involved. The clinical presentation of histiocytic sarcoma may be unusual, and neoplastic cells may lack overt features of malignancy on cytologic and histopathologic examination. In some instances, immunophenotyping is required to differentiate histiocytic sarcoma from other histiocytic disorders.

Diagnostic Immunohistochemistry of Canine and Feline Intracalvarial Tumors in the Age of Brain Biopsies

“…3). 80 Occasionally, dim CD18-positive flow cytometric staining has been reported in feline lymphomas. 29 Lysozyme and RCA-1 lectin are additional markers successfully used in FFPE tissue.…”

Morphological Distinction of Histiocytic Sarcoma from Other Tumor Types in Bernese Mountain Dogs and Flatcoated Retrievers

“…The characteristic kidney-shaped nuclei have also been reported before in canine HS (33,39,46) and in human HS (47) and IDCS (14). Indentations of the nucleus have been reported in the canine literature (1,7,24,26,28) as well as in human HS (41) and IDCS (48), and a combination of indentations, grooves or folds in human HS (43,49), IDCS (14) and LCH (50). This indicates that a canine subtype comparable to human LCH/LCS may also exist.…”

“…Both in our study, as well as a earlier report (24), spindle cells were more often seen in this localized form compared to the disseminated HS. Spindle cells have been reported in canine HS before, but only in combination with round-oval cells (1,(24)(25)(26)(27)(28). This makes this study the first report of HS cases with spindle cells only.…”

“…The infiltration of lymphocytes only has been reported before in canine HS (1,6,20,24,28,39,52), but inflammatory patterns of neutrophils only (34), a combination of lymphocytes and plasma cells (25), of lymphocytes and neutrophils (7), of neutrophils and eosinophils (33), and of lymphocytes, plasma cells and neutrophils (1,26,25,51) have also been reported. The difference between BMD and FCR with regard to inflammatory pattern, with BMD having more often small lymphocytes, has not been reported before as far as we are aware.…”

Respiratory Tract

“…Several presentations have been identified, including lymphoma and histiocytic sarcoma. More recently histiocytic neoplasia in the dog has been defined as a spectrum of diseases characterized by proliferation of Langerhans dendritic cells, interstitial dendritic cells, or macrophages (Affolter and Moore, 2000;Affolter and Moore, 2002;Mastrorilli et al, 2012;Moore et al, 2006;Moore, 2014). 5-62A&B).…”