CHAPTER 25 HISTIOCYTIC PROLIFERATIVE DISORDERS 383
Weight loss
Respiratory stertor
Coughing
Dyspnea
Dogs with systemic disorder may not have signs of systemic illness
Marked predilection for skin and lymph nodes
Moderate to severe peripheral lymphadenomegaly often present
Abnormal respiratory sounds and/or nasal mucosa infiltration (Figure 25.9)
Organomegaly occurs with systemic involvement
Lesions may develop in the lung, liver, spleen, bone marrow, and nasal cavity
May have alternating episodes of exacerbation and remission. Histiocytic sarcoma complex:
Pallor
Weakness
Lethargy
Weight loss
Primary pulmonary disease; dyspnea with abnormal lung sounds
Lameness, joint swelling
Neurologic signs (e.g., seizures, central disturbances, and posterior paresis)
common
Moderate to severe lymphadenomegaly
Hepatic, splenic, renal, and pulmonary involvement common
Occasionally, masses are palpated in the liver and/or spleen
Eyes and skin are rarely affected
May be localized: rapidly growing soft tissue mass most often on extremities(Figure 25.10)
Highly metastatic (91%)
Multiple firm dermal to subcutaneous nodules that may be alopecic or ulcerated;lesions occur anywhere on the body.
Malignant fibrous histiocytoma:
Soft tissue sarcomas
Predilection for the shoulder and paw
Locally invasive to bone, muscle, organs
Widespread metastasis common
May present as an injection site sarcoma.
DIFFERENTIAL DIAGNOSIS
Histiocytic (nonepitheliotrophic) lymphoma: differentiation and definitive diagnosis
often require special staining for immunohistochemical markers.
Lymphomatoid granulomatosis: extensive pulmonary infiltrate of lymphocytes,
plasma cells, histiocytes, and atypical lymphoreticular cells; affects young to middle-
aged dogs, with respiratory disease as the chief complaint; lack of lymph node, organ,
or bone marrow involvement.