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Thread: Histiocytoma?

  1. #1

    Default Histiocytoma?

    anyone got any info on Histiocytoma? If so I would appreciate anyone with knowledge on this, for some info.

  2. #2
    Join Date
    Nov 2006
    Fort Worth Texas

    Default Re: Histiocytoma?

    Quote Originally Posted by crustyjodie
    anyone got any info on Histiocytoma? If so I would appreciate anyone with knowledge on this, for some info.
    I think this is about everything you need to know on that subject.

    Skin tumors are the most commonly diagnosed neoplasms in veterinary medicine.2 These neoplasms represent a diverse group of benign and malignant growths arising from a variety of cell types. Determining the origin of cutaneous neoplasms is often challenging, but is of paramount importance in many patients regarding therapeutic considerations.
    Cutaneous histiocytoma is classified cytologically as a round cell tumor. Other members of this tumor group in dogs include mast cell tumor, cutaneous lymphoma, transmissible venereal tumor, and plasmacytoma. Treatment and prognosis for the various round cell tumors vary considerable. Therefore, accurate diagnosis is required.

    The name "histiocytoma" implicates a benign neoplasm of monocytic cell lineage, but obscures the exact origin of these neoplastic cells. Histiocytes are mature macrophages that reside in connective tissue.12 They usually originate from blood monocytes which comprise about 5% of the circulating leukocyte population.

    Research indicates that a variety of histiocytic proliferative disorders affect dogs. These include cutaneous and systemic histiocytosis, cutaneous histiocytoma, localized histiocytic sarcoma, and disseminated histiocytic sarcoma.1

    Most evidence indicates that cutaneous histiocytomas are derived from a more specialized population of cells called Langerhans cells.6, 8, 9 Langerhans cells are a developmental subset of the antigen presenting cells known as dendritic cells. The development of dendritic cells is well described, and at least three major precursors are known; myeloid series, monocytic series, and a lymphoid series (Fig. 1).10

    Figure 1. Schematic indicating the proposed lineage of Langerhans cell development from myeloid, monocytic, and lymphoid precursor cells.

    Cancer is one of the major causes of death in dogs.3, 7 There is a large amount of clinical information regarding clinical signs, diagnosis, and treatment of canine neoplasia; however, relatively little information exists on the incidence of many types of cancer in this species. It is well accepted that cutaneous neoplasms are among the most commonly observed forms of cancer in dogs. Furthermore, cutaneous histiocytoma has been reported to be the most common presentation of cutaneous neoplasia, and the most commonly observed form of cancer overall.6,7

    Canine cutaneous histiocytoma is most commonly observed in young dogs and tumor incidence drops precipitously after three years of age. While this tumor is most commonly observed in young dogs, most studies indicate that it is infrequently observed in older animals. Breeds at risk include Flatcoat Retrievers, English Bulldogs, Scottish Terriers, Greyhounds, Boxers, and Boston Terriers.

    Gross Lesions
    Cutaneous histiocytomas are generally observed by the practitioner as solitary, red, dome-shaped, sparsely haired nodules that appear rapidly (Fig. 2). They often are ulcerated, but are non-painful. The most common sites of tumor development include the head, pinna, and neck, especially in young dogs.3 More rarely, neoplasms may occur on the trunk and extremities, and frequently involve the feet and toes of older individuals (KSL, personal observation). Rarely, histiocytomas may arise in multiple sites.

    The metastatic potential of histiocytomas has not been studied directly, but reports of tumor metastasis are rare. Death due to cutaneous histiocytoma has not been reported. It is generally accepted that this tumor does not readily metastasize, and should be considered benign.

    Figure 2. Histiocytomas of the pinna (left) and foot (right) appear as red, raised, sparsely haired m$#@! (Courtesy of Noah's Arkive, University of Georgia).

    Cutaneous histiocytomas may be readily diagnosed using a combination of clinical signs, signalment, and fine-needle aspiration cytology. Rarely, a histopathologic diagnosis may be required. In biopsy sections, histiocytomas are circumscribed, nonencapsulated dermal m$#@! composed of sheets of round cells. Individual cells have a round to reniform nucleus with occasional nucleoli and moderate amounts of cytoplasm(Fig. 3). Increased mitoses, discrete necrosis, and infiltrates of small lymphocytes may be observed. Infrequently, cutaneous histiocytoma may be confused histologically with granulomatous inflammation, poorly granulated mast cell tumors, plasmacytomas, and cutaneous lymphosarcoma.2

    Figure 3. Biopsy specimen of a histiocytoma composed of sheets of round cells. Scattered mitoses are present (Hematoxylin and eosin stain, courtesy of Noah's Arkive, University of Georgia).

  3. #3
    Attila Guest

    Default Re: Histiocytoma?

    often frozen and removed like warts. They have a core that is in the dermis layer so it requires a vet to do it. A core that is much like the shallow root of plant.

  4. #4
    Join Date
    Feb 2006
    SW PA.

    Default Re: Histiocytoma?

    The main thing I know about them is, you have to get them checked out because it can be hard to tell if your dealing with a malignate tumor or a Histiocytoma just by looking. Just this past winter my dog had one and we and the vet thought it was cancer due to his age. Thank God it was just a Histiocytoma.


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