Histiocytic Neoplasms of the Dog and Cat

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1 Histiocytic Neoplasms of the Dog and Cat V.E. Valli DVM Histiocytic and Dendritic Cell Populations Both lineages are bone marrow derived. Macrophages are part of the innate immune system that are phagocytic and produce a range of cytokines. The interstitial dendritic cells home to the epithelium and become the Langerhans cells that carry antigen to the node follicles A third line of cells forms the antigen presenting cells of the node paracortex 2 Characteristic staining patterns Macrophages in tissues are CD11b+,CD14+ and CD68+ Dendritic cells in tissues are CD1+ and CD11c+ 3

2 Histiocytic Neoplasms Cutaneous Histiocytoma a benign dermal proliferation usually in young dogs of Langerhans cells Cutaneous Reactive Histiocytosis a multifocal dermal proliferation of interstitial dermal dendritic cells of variable progression 4 The Histiocytoses Cont d Systemic Reactive Histiocytosis a disease of Bernese mountain and other breeds of dogs composed of large solid masses of non-neoplastic interstitial dendritic cells Histiocytic Sarcoma an aggressive malignant neoplasm of dogs and cats composed of non phagocytic histiocytic cells Hemophagocytic Histiocytic Sarcoma a fatal neoplasm of avid erythrophagocytosis 5 Canine Cutaneous Histiocytoma A high up dermal proliferation of round cells that have many reniform shaped nuclei and tend to be self limiting in younger dogs The cells are of non-activated epidermal dendritic or Langerhans cells that are Thy- 1 or CD90+ 6

3 Histiocytoma Dog History A 3 year old FS Rottweiler was presented with a 1cm raised round mass in the center of the anterior surface of the left ear A FNA was taken and stained with a Wright/Giemsa preparation 7 Histiocytoma Dog Cytology 8 Histiocytoma Dog History A 2 year old FS Boxer dog was presented with a dermal mass on the left thigh that had been present for the last month and was now ulcerated and bleeding Excisional biopsy was carried out and the mass was stained with H&E. 9

4 Histiocytoma Dog Histology 10 Detail Histiocytoma Dog Histology 11 Canine Cutaneous Histiocytosis History A 6 year old MN Golden Retriever was presented with multiple areas of patchy alopecia with some response to Prednisone. Punch biopsies were taken from the muzzle area and a full thickness biopsy from the right front limb and an enlarged mandibular node was excised Cells of similar type were present in all sites 12

5 Histiocytosis Dog Skin from Right front limb 13 Detail Histology Canine Histiocytosis 14 Histiocytic Sarcoma Dog History A 6 year old MN Bernese Mountain Dog was presented for examination because of Sternal and mediastinal lymphadenopathy with a cranial abdominal mass. FNA was taken of sternal node and diagnosed as Histiocytic Sarcoma 15

6 Histiocytic Sarcoma Dog Cytology 16 Histiocytic Sarcoma Dog History An 9 year old MN Basenji Dog was presented with enlarged with mandibular and prescapular lymph nodes. A Tru-cut biopsy was taken of the prescapular node that was interpreted to be a pleomorphic round cell sarcoma, likely histiocytic sarcoma and immune staining was recommended. 17 Histiocytic Sarcoma Dog Histology 18

7 Detail Histiocytic Sarcoma Dog Histology 19 Histiocytic Sarcoma Dog Histology B-Cell CD79 T-Cell T CD3 20 Histiocytic Sarcoma Dog Histology Histiocyte CD18 21

8 Feline Progressive Histiocytosis History (early case) An 11 year old FS Domestic Short hair Cat was presented with an intradermal mass on the ventral abdomen 2.0 x2.0 x0.5 cm that was noticed by the owner a week previously. The cat was irritated by the mass and was frequently licking the affected area. A FNA of the area was taken for diagnostic purposes. 22 Feline Progressive Histiocytosis Cytology 23 Detail Feline Progressive Histiocytosis Cytology (early case) 24

9 Feline Progressive Histiocytosis History (late case) A 16 year old Domestic Shorthair Cat was presented with multiple masses on digits 3 and 4 of the RR paw unresponsive to antibiotics. The cat now has an enlarged right popliteal node. Prior FNA s were interpreted as pyogranulomatous inflammation. Further FNA s were taken of the node and several areas of the foot. 25 Feline Progressive Histiocytosis Cytology 26 Detail Feline Progressive Histiocytosis Cytology 27

10 Feline Progressive Histiocytosis Cytology Popliteal node 28 Detail Feline Progressive Histiocytosis Cytology Popliteal node 29 Conclusions Histiocytic Neoplasms Cytology and Histology are equally capable of providing an accurate diagnosis especially if coupled with IHC In the dog Histiocytic Sarcoma is frequently found surrounding a limb joint with the tumors cells thought to arise from the dendritic cells of the synovial membrane 30

11 Conclusions Cont d Histiocytic Sarcoma is much more commonly encountered and variable in presentation in the dog as compared to the cat Anecdotally HS in the dog maybe mistaken for large cell lymphoma and treated for that disease resulting in a remission lasting for months Tissues taken from initial sites of tumor maybe free of tumor at necropsy despite widespread metastases 31