Diagnosis
Diagnosis requires a biopsy.
Histiocytic Disorders
A histiocyte is a differentiated tissue cell that has its origin in the bone marrow. The source for histiocytes is the monocyte/macrophage line. Monocytes (found in the blood) and macrophages (found in tissue) are responsible for phagocytosis (ingestion) of foreign material in the body. Langerhans cells are dendritic cells found in the skin and function by internalizing antigens (foreign particles) and presenting them to T cells. They arise from monocytes. Histiocytic disorders refer to diseases that are caused by abnormal behavior of these cells.
They include the following:
Reactive Diseases of Langerhans Cells
Histiocytomas
Cutaneous histiocytosis
Systemic histiocytosis
Reactive Diseases of Macrophages
Hemophagocytic syndrome
A condition where macrophages phagocytose myeloid and erythroid precursors (similar to hemophagocytic lymphohistiocytosis in humans)
Malignant diseases of Langerhans dells
Malignant histiocytosis
A condition found in Bernese Mountain Dogs
Diffuse histiocytic sarcoma
Localized histiocytic sarcoma
Malignant Diseases of Macrophages
Histiocytic lymphoma
Breed Disposition
Up to 25 percent of Bernese Mountain Dogs may develop malignant histiocytosis in their lifetime. Other breeds with a possible genetic tendency toward malignant histiocytosis include Rottweilers, Flat-Coated Retrievers, and Golden Retrievers.
Treatment
Treatment with chemotherapy has been used with some success, particularly using lomustine, prednisone, doxorubicin, and cyclophosphamide. Because of the rapid progression of this aggressive disease, the prognosis is very poor.
Other Histiocytic Diseases In Bernese Mountain Dogs
A similar disease is diffuse histiocytic sarcoma, a term used to designate a localized histiocytic sarcoma that has spread throughout the body.
Another disease of histiocytic origin that affects Bernese Mountain Dogs is systemic histiocytosis. This condition generally begins as lesions on the eyelids, nasal mucosa, and skin, especially the scrotum. It progresses to a more generalized disease affecting the lymph nodes, bone marrow and spleen. Other signs and symptoms include weight loss and loss of appetite. It also has a very poor prognosis.